Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: hughes674 on July 12, 2018, 02:48:23 PM
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Hi All
Just started a conversion using the CS LABS CSMIO/P-A controller on my Denford Senior Lathe. I am using the original Sem Servo Motors and Dc Drives. Just trying to wire up the one axis at the moment and not sure whether or not you have to supply 10v to the Analog I/0 connector or does the controller deal with this internally. There is a 10v connection point but unsure if this is necessary.
I can upload the manual or email it.
Thanks
Mick
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No, you don't need to supply 10V. The 10V line you mention is an output that you can optionally use to power potentiometers or the likes.
The CSMIO servo outputs are the 6 +/-10V outputs and you should connect one of these and its associated 0V to the drive you are using.
You will also need to wire the drive's encoder outputs to the IP-A's encoder inputs for the same channel.
Allan
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Thanks Allen
I have wired the encoder and Vrefs. Was just unsure about the 10v. I will give it try tomorrow. Little unsure about what to enable in ports and pins but will give it a go.
Thanks again.
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Hi All
Wired up the x axis on the CSMIO/P-A controller and can't get any movement.
Encoder wired to channel 0
A+ A- B+ B- Z+ Z- GND 5 DC. All the wires are clearly marked and colour coded on the encoders.
Command Hi and Low connected to pins 1 and 14 on the analog I/O
Mach 3 Config
Motor Outputs
X Enabled step pin 2 direction pin 6??
Encoder output. Have enabled encoder 1 to port 10 but not really sure what else to do here?
If I disconnect The command Hi Low wires and put a 1.5v battery across the wires and the axis moves.
All the limit switches and emergency stop signal are wired and working correctly.
Would really appreciate some help. Never used servos before and have read the manual now about 5 times.
The controller is showing no errors just waiting for command.
Thank you
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Sorry, I have no knowledge of Mach3 so maybe someone else can help here.
You sound to have the basic connections correct, and the drives must be enabled as you say the battery causes movement. But why are you using step and direction Pins? The CSMIO/IP-A is an analogue controller, so don't you need to set up the Ch0 analogue output within the CSMIO plugin to get it working? Similarly, what is the port 10 you mention for the encoder? Again the encoder outputs from the drive connect directly to the IP-A and settings are handled within the plugin, not Mach3.
I may be wrong, but the pins you mention seem appropreate to the CSMIO/IP-S rather than the IP-A. Presumably you are using the correct plugin and it gives you the required settings for the IP-A?
Allan
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Cheers Allan
The encoder output is in the mach 3 configuration. I'm not sure if this is necessary at all?
It doesn't seem to mention it in the CSMIO/P-A manual.
Could this be a motor tuning issue? When the drive is enabled I can turn the motor by hand. There is a little resistance but not a lot. The motor hums a little at stand still.
Cheers
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OK. I had a quick peep at the manual and see that the ports and pins you mention are ignored by the controller.
It could be tuning, as it sounds as if the drives are powered and enabled. You should tune the servo drives first. This can normally be done using an auto-tune utility.
Once you have the servo drives tuned, begin with the IP-A. Progressively increase the proportional gain. For now the other coefficients can be set to 0. The motors should start to feel stiffer as the servo takes control. If the motor starts and continues to the end of travel, you probably have the encoder feedback set incorrectly and need to reverse its direction in the plugin. Once you get to the point that the motors feel reasonably stiff yet remain stable, try using the IP-A's auto-tune feature, which I have found works quite well. You can always tweak things manually later if need be.
Allan
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Hi Allen
What do you mean by auto-tune utility? I have the drive manual and it explains how to tune the drives. The command gain seems straightforward enough but as for the for others, eg Tach gain, Peak current limit, stability seems a little more involved.
The drives and motors were working fine on the old Fanuc Ot Control. The reason for the refit was due to an unknown fault on the operator panel. Is it more likely to be the tuning in the CSMIO rather than the drives themselves?
Mick
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Hi Mick
OK, it sounds as if your drives are elderly and don't feature auto-tune. Also, as they were working properly before, you are quite right to assert that they should already be optimally tuned, so we will assume that this is so.
Yes, the CSMIO will need tuning to match your system: there is no default here as all systems differ. As I suggested above, you should begin by increasing the proportional gain. This serves 3 purposes: It demonstrates that the system is functioning at a basic level, it enables you to ascertain that the encoder feedback is of the correct polarity, and it provides a basis from which you can proceed to auto-tune or manually tune the controller.
Allan
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Mick
I've just looked back and see that your system is totally different to what I have: You use a lathe, mine is a mill. You have dc servos, and mine are the more modern ac type. So I'm still hoping someone with a similar setup may jump in here and help.
One thing I notice is that you make no mention of your basic motor settings. Be sure before attempting any tuning that you have correctly entered your encoder counts per revolution in the CSMIO plugin, and have the counts per unit set in Mach4's motor settings.
Allan
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Hi Allan
Yes, they are DC Servos. I now have movement of the X-axis :D. The way the manual tells you to set up the servo is to enable the drive with 0v and adjust RV1 on the drive until movement stops. It then tells you to apply max voltage (10v) to the drive and adjust the command gain RV2 on the personality module until the desired rpm is reached. The first part works but when applying 10v to the drive and adjusting RV2 it makes little difference to the speed. There are other adjustments on there as I said before but I don't fully understand what to do with them.
I have axis movement when I run a simple program but the speed is very limited to around 300mm minute.
The CSMIO manual says to set the steps within mach3 as follows for the motor tuning. PPR / pitch. My encoders are 2500ppr and I have a ball screw pitch 0f 5mm. This gives 500 which I have entered into the motor tuning in Mach 3. I understand you're not into Mach 3 but just giving you a rundown.
I'll try tuning the CSMIO controller and see what happens.
Appreciate your time on this thanks.
Mick
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Mick
Glad you are moving in a forward direction.
As you have movement you might like to do a quick check that you are moving the correct distance. For example, enter asimple move of 50mm using G1 G91 X50 F100 or something similar into Mach3's MDI line and check that movement is the correct distance. I suggest this just to check that your encoders deliver 2500 pulses per rotation as opposed to 2500 lines, as the latter would give you 10000 pulser per rev. Otherwise your arithmetic is fine. Be sure to use the pulses, rather than lines per rev in the CMIO plugin as well.
Allan
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Thanks, Allan
It says on the encoder PPR 2500. Nothing about lines. I'm setting Mach 3 motor outputs tuning steps to 500 and in the CSMIO I'm setting to 2500. (Should this be 500 as well)?
I'm having loads of issues.
Unable to increase the speed of the motors past around 300mm minute.
The motors are completely out of sync with mach3. Mach 3 gets to the correct position and stops whilst the motors carry on. I think it is due to the program having a higher speed command than the motors are delivering.
Tried to autotune in the CSMIO but it doesn't work. Left it running for around half an hour. I set the KP at 550 anything over that and the motor starts moving. The auto-tune took the KI over 100,000 and was still going.
I have attached a picture of the encoder. It's not that clear on the photo but definitely says PPR 2500.
Mick
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Hi,
best guess is that 2500 PPR is 2500 line encoder and therefore 10,000 counts per revolution.
Craig
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Thanks Joe.
Just been reading up on encoders. My encoders have A A- B B- Z Z- which I think makes them quadrature output. So if I understand correctly the PPR could be 2500X4 counting all edges. Making it 10000 pulses per revolution?
This is frying my brain.
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Set the motor output steps in Mach 3 to 2000. 2500PPR X 4/ Pitch 5mm. Set The CSMIO motion controller to 10,000 PPR. Done the auto-tune on the CSMIO. The X-axis now moves accurately within 100th MM.
Still cannot get the motor to run over 60 rpm?? The feed rate does not increase over approx F300. The CSMIO is outputting 10v when a high-speed command input is entered.
Has anyone got any ideas? Is it Mach 3 configuration, a servo drive problem or Configuration of the CSMIO?
Really could do with some help here. Thanks, Allan and Joe so far.
Mick
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Hi,
you say the CSMIO is producing 10V.....is that the output that goes to the drive?
If that's the case the drive should be producing max voltage/current to the motor. If you hook a 9V battery to the signal input
of the drive the servo should go flat-out or close to it.
Craig
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Hi
Yes if you put a feed rate of say 5000 the controller puts 10v on the command Hi Low input to the drive. I have already tried a 9v battery and the speed doesn't increase any more than it does for a 1.5v battery. It does sound like a driver issue but they were working fine with the old controller. There was never an issue with the speed of the motors.
Mick
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I also had a rather frustrating afternoon. Went to use the bandsaw for a bit of domestic renovation and to my surprise and dismay it wouldn't go. Opening it up I found a mouse nest in the base and the little so and so's had completely chewed through one of the internal cables: sheath, insulation and copper, the lot. It will be quite an awkward job to fix. Oh well, the joys of living in the English countryside.
Craig
Thanks for stepping in. I suspected the encoders would be 10000ppr. I have no experience of these dc servos and drives at all, so could do with your knowledge of this stuff.
Mick
The CSMIO cannot produce more than +/-10V however it is tuned, and that should cause your motor to reach maximum speed. So either the servo's gain is lower than expected, or the motor is current limiting for some reason. Does the servo drive have any diagnostics or error indications? I guess I've been spoilt by modern ac servos and drives.
You need to be confident the drive is working and tuned correctly before you can sensibly tune the CSMIO. Your current settings sound very strange to me, I would expect the proporthional gain setting to be a lot (10x ?) higher than the integral gain. But I would leave the CSMIO until you have resolved why the drive cannot produce the motor speed you expect.
Do you have the original or the FP4 version of the CSMIO ?
Allan
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Hi Allan
I ordered the CSMIO straight from CS labs. Not really sure what you mean as far as being original? I have posted on the Denford forums to see if anyone can advise on tuning the drives as they are off one of there machines.
It does look like a drive issue but doesn't make sense??
Those mice can be a nightmare. :-[8
Mick
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Mick
I think you are doing the best thing by checking in the Denford forum.
The CSMIO was updated by CS Labs a couple of years ago, and the new version was externally labelled FP4. If you purchased it recently you will have the FP4 version and it will be so marked on the front. Either way you are presumeably using plugin version 2.910, which is the latest that supports Mach3.
None of this is material to your issue, I was just interested. I have the FP4 but use the v3 plugin for Mach4.
Allan
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Hi,
I have already tried a 9v battery and the speed doesn't increase any more than it does for a 1.5v battery. It does sound like a driver issue but they were working fine with the old controller.
That doesn't sound right. If the servo amp and servo can't do the business it won't matter
how you tune the CSMIO.
You absolutely HAVE TO GET THE SERVO TO RUN AT MAXIMUM OUTPUT if you are ever to have the chance of tuning the controller.
Craig
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Hi,
could your servo amp be current controlled not voltage controlled?
Craig
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Craig
Could it further be that even if the servo is voltage input, it is set for position or torque control rather than velocity control?
Allan
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Hi,
your right Allan, its definitely sounding like the servo amp is either faulty or set up differently.
Craig
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Hi,
if this is an analogue input servo amp then position,velocity or torque mode don't make
sense.
Analogue voltage (or current) input is amplified to an analogue output that is a voltage and
current, for a shaft output of speed and torque.
The servo is in position when the error between the step/dir command and the encoder feedback is zero,
this calculation/measurement is made by the controller, in this case the CSMIO.
Craig
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Hi hughes674,
can you post the details of the servos and especially the servo amps?
Pics, manuals and anything else you've got.
Craig
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Manuals attached. Failed Last time.
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Really appreciate your time on this. I'll post anything I get back from Denford.
Mick
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Hi,
what model motors do you have?
Do they have a Tacho?
Is the Tacho hooked up?
When you hooked up the 9V battery the servo should have gone nuts, nearly full speed, if it didn't you have a problem that must be sorted
before hooking it to the CSMIO.
To what terminals did you hook the battery?
Note there are Hi and Lo Tach terminals and Hi and Lo Command terminals....you want Command terminals.
Craig
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Mick
Thanks for the manuals. I see now what type of kit you have.
The motor speed is proportional to the (effective) armature voltage applied to it. As you have applied both 1.5v and 9.5V and these resulted in similar speeds, something is clearly wrong and I would start by checking the bus voltage, as this is the maximum that can possibly be provided by the bridge output circuit of the drive. I'm not sure which motor you have but the specs give the voltage factors per radian per second so this should enable you to estimate the required voltage for the maximum speed you need to operate at.
The drives appear to be designed for a voltage input, so we are OK in that respect. They either implement a simple (switched mode) amplifier or a velocity loop if you have the tacho installed. Either way, they convert input command voltage to motor speed, which is what we need.
Sorry if this seems tedious, but we need to proceed logically one step at a time to try to identify the issue. If the bus voltage seems OK then something within the drive must be limiting its performance.
As Craig says, advise us if you have the tacho installed.
Allan
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Hi
Yes tacho is installed. The motors are mt30. The wires I am using for the speed command are command HI low.
I can check the bus voltage when I get home. Pretty sure it's 130v when I checked it before.
Mick
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Hi,
looks like these drives can have a velocity characteristic which requires a tach, or a torque characteristic that doesn't require a tach.
The difference is determined by the 'personality' board installed in the drive.
Are the drives and servos matched? Are they complete with all their original bits?
Are the tachs hooked up? Is it possible to wire them backwards?
The Command input is differentially signaled, ie two inputs command hi and command lo. You can wire them single ended as well....how have you
wired them? Be accurate about this, sketch it, check it, check it again, and check it a third time.
How is the CSMIO output configured....differential or single ended? There again no guessing....either sketch it and check the sketch per above or direct
from the CSMIO manual.
Craig
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Mick
There are a few variants of the motor, with a voltage coefficient ranging from approximately 20V to 50V per 1000rpm. So your bus voltage sounds crudely OK but it might be worth a quick check under load.
You said you connected CSMIO pins 1 and 14 to the command + and command -. That is correct. The input circuit can certainly withstand +/-10V
Do you have a spare card that you could quickly swap in as a quick and easy check on the drive? You may need to keep to the existing personality module.
I'm off to work on a sick bandsaw now so will sign out for a while.
Craig
CSMIO has signal and ground outputs for each channel, so it sounds to me as if they are single ended but can conveniently be wired to the differential opamp using STP.
Allan
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Hi,
well if the CSMIO is natively single ended then OP should wire the input of the drive the same way.
According to the manual take Command Lo to 0V, Command Hi to the output of the CSMIO and common both 0V.
You need to set a command of 10V so that the servo goes to max speed, ie will have to disconnect from the leadscrew.
The Command Gain pot should then set the max output voltage which is proportional to speed.
Craig
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Hi,
got to say these servos and drives are OLD SCHOOL!. To OP: if they even look like crapping out don't waste your time and money fixing them,
get yourself some decent AC servos....modern ones......no bull********* having a controller to close the loop either....proper matching closed loop drives.
I have an Allen Bradley servo for a spindle motor....just brill! I bought second hand reasonably cheaply, they are way too expensive for me new
but Delta and DMM do some very very good stuff which will eat these servos...
Craig
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Hi Both
Sorry for the delay. Heres what we have.
Sem MT30H4-33 Motors
Norwin 2110 drive
Encoders:
A+ Brown pin 1 ON CSMIO
A- Yellow Pin 14 ON CSMIO
B+ Red Pin 2 ON CSMIO
B- Green Pin 15 ON CSMIO
Z+ orange Pin 3 ON CSMIO
Z- Blue Pin 16 ON CSMIO
5VDC White Pin 4 ON CSMIO
GND Black Pin17 ON CSMIO
Tacho Connected to pins 1 and 2 on the Servo Drive card going directly into the motor. This has not been touched, it is the original wiring.
Command Hi and Low going to pins 1 and 14 on the I/O of the CSMIO. The wiring for this has not been touched either on the servo side.
I have 108vdc at the bus on the drives.
The Only wires that have been disconnected are the Command Hi-Low and the encoder.
Am I right in assuming that the 5vdc on pin 4 of encoder channel 0 supplies the 5 volts to the encoder?
There are only two wires coming from the command Hi-Low. This is the original wiring. I am not sure what you mean by single end wiring and configuration for this?
Could this be anything to do with Peak Current Limit pot on the personality module? Haven't tried adjusting it as they were fine before.
Thanks for your time on this.
Mick
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Hi,
There are only two wires coming from the command Hi-Low. This is the original wiring. I am not sure what you mean by single end wiring and configuration for this?
The two wires are differential inputs whereas the CSMIO is single ended. Command Lo needs to connect to 0V on the CSMIO.
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Hi,
sorry hit <post> prematurely.....
Command Lo connects to CSMIO 0V
Command Hi connects to CSMIO analogue output
0V (pin4 TB3) connects to CSMIO 0V
Confirm the wiring.
Craig
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Hi Craig
Thanks for your input on this. Can you simplify it a little more, please? I have attached the CSMIO page for I/O connector. I presume red will be high and blue low? At present, I have connected the red and blue wire to pins 1 and 14.
Is TB3 pin 4 on the servo drive? There has never been a wire attached to this pin.
Cheers Mick
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Hi All
The wiring checks out correctly as we have previously established. I think you are better off using STP to pins 1 and 14 of the CSMIO rather than grounding locally as I think Craig was implying. The quasi-differential connection I recommend could reduce ground noise slightly, at least at low frequencies. The encoder
Your encoders are correctly wired including 0V and 5V. The 5V is indeed supplied by CSMIO to power the encoders. In any case you said that the encoders were working correctly when set for 10000 counts per revolution.
Your motor needs 33V per 1000 rpm, so you should be good for something approaching 3000 rpm maximum speed.
I wouldn't adjust the current limit at this point as it should already be set correctly. It would perhaps be worth applying 10V as Craig suggests and adjusting RV2 (command gain) to see if you can achieve anywhere near the desired speed. As Craig says, initially do this with no load on the motor. I don't hold out much hope, as I believe you said you had applied over 9V using a battery and that you had adjusted the gain pot.
If you still have negative results, I again suggest the easiest way to confirm if the drive is dead would be to swap it out with another.
I tend to go along with Craig in that if the drive is defective, it would be better to ditch it and replace with ac servo motors and matched drives, but of course that will cost you a significant amount, as well as having to potentially modify the mechanical arrangements and wiring - altogether quite a bit of work.
Allan
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Hi Allan/ Craig
Craig can you simplify the wiring suggestions from your last post please.
Done some more checks and the Voltage at the bus is 103v when under load. A drop of 5v so I presume this is ok.
The interesting thing is no what speed command is entered in mach the voltage at pins 1 and 14 (Command Hi Low) is always 10.50v. This is from a speed input of F10 to F1000.
Cheers
Mick
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Mick
The CSMIO output is not simply proportional to speed, it is a function of position error. You have such a high integral gain that this is likely to rapidly force the output to 10V unless the motor is stationary. I would suggest that for now you manually set all but the proportional gain to zero in the CSMIO manual tuning. Increase the Kp until the motor just starts to oscillate, then back a little. Aim for the maximum Kp without oscillation. If the motor starts to run away rather than oscillate reverse the sense of the encoder (tick box in the plugin).
I was just thinking that we are currently tending to suspect the drive as being potentially faulty, but could it be that it is the motor itself that is bad. Maybe loss of field magnetisation, for example. I am just thinking aloud that the motor would be a lot easier to test than the drive, as potentially you would only need to supply armature valtage at sufficient current. See what Craig thinks about this as a possibility.
Allan
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Hi Allan
Thanks again for your time. I will try this again tomorrow. I am convinced this is a setup error as these motors and drives were working perfectly before an error occurred on the OT Control and shut the machine keyboard down. It's not a problem to swap the motors over so will try this if Adjusting the Kp doesn't work. If all fails I will send one of the drives to be tested. They offer a fixed fee repair on the drives for £150 so if they were both faulty it wouldn't be the end of the world.
Don't want to give up on them just yet. the machine has done very few hours.
Cheers
Mick
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Mick
I wholly understand your wish to use what you have if at all possible. I would be the same. The thing that makes us suspect a fault is simply that you have stated that the motors would not run at full speed when you applied 9V to the command imput and adjusted the gain pot. But nothing quite makes sense at this stage so we need to try to narrow things down.
At least we are now confident of your wiring and of the power supply to the bus.
I may not be around much over the next 3 days as we have visitors and other committments.
Allan
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Hi Both
Couldn't resist having another go. Don't know why but disconnected the Tacho Wires from the drive and the Motors run at full speed. Fully controllable from speed commands in Mach. I think means the drives and Motors are working fine. Any suggestions why this might be happening?
Cheers
Mick
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Sounds as if the tacho gain may need adjustment, but will have to leave this to Craig as it is getting late for my brain. There is mention in the manual of adjusting the tacho to match it to the command voltage, but I'm not sure what this actually does and there is no circuit diagram. In any case, Craig is most likely to have experience in this area.
It would also be worth measuring the tacho output to see if it is within the expected limits.
Allan
Allan
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Hi,
It would also be worth measuring the tacho output to see if it is within the expected limits.
Good idea, get the servo spinning as fast as you can, preferably with some means to measure the speed and
then measure the output of the tacho and compare to the spec.
When I get home tonight I will look a bit more closely, but what it amounts to, at the moment, with you having disconnected
the tacho, is that amp is now a 'voltage driven current output amplifier' also called a transconductance amplifier.
By disconnecting the tacho you have broken the feedback loop which turns the transconductance amp to
a 'voltage driven voltage output amplifier'. Note this feedback loop is within the drive and has nothing to do
with the PID dynamics of the CSMIO.
Much of my University experience with these devices was with a plain transconductance amp, ie torque mode.
Unless someone can tell me what advantage having the extra feedback loop, especially as it doesn't seem to work,
is I would not bother with it. That is a very preliminary assertion on my part and thorough investigation is required
before you adopt the idea.
It may be for instance by removing the tacho feedback you have effectively increased the command gain to where it should be.
Thus with the tacho loop reinstated AND the command gain increased to where it should be then the setup would
now work as the manufacturer intended.
Craig
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Thanks Craig
I will remove the motor tonight and start again without the Tach connected. Once I have matched the voltage from the Tach to the Command I will try reconnecting. This couldn't be some kind of phasing issue? Eg swapping two wires on a three-phase motor makes the motor run opposite. Just thinking if the motors are turning opposite to what the controller thinks they are would the Tach be running the wrong way?
Mick
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Hi,
yes it could be but usually what happens if the direction of rotation is inconsistent the axis will run away too one end not
just go slow.
Craig
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Hi,
I don't know if this will help...a bare bones explanation as to how your drives work...or at least supposed to work.
The first pic is a straight openloop transconductance amplifier. Note that there is no means of adjusting the gain. Also the amplifier gain will vary with
temperature, load and DC link voltage, in short the gain is not particularly stable.
The second pic uses feedback to produce a much more stable gain. When the forward path gain ( G.Ki ) is large then the output current is a faithful
amplification of Vin divided by a constant. In practice this constant is gain setting resistors or a pot. Now the gain is easily adjustable and
stable, a marked improvement over the openloop amplifier. This sort of servo amplifier is used for torque mode control and is very common...well used to be,
they are getting to be a dying breed now!
The last pic shows the same transconductance amp as above but the servo has been added with an attached tacho. Note that the output of the amplifier is
still the current, Iout. The current produces a proportional torque and therefore angular acceleration in the servo resulting in a shaft rotational speed
of W. The tacho produces a voltage proportional to W for the feedback circuit. The speed W is a scaled 'integral' of the current.....you may have thought
you could get away WITHOUT calculus....but no such luck! I have tried to keep the maths to a minimum but the upshot is that with a high forward loop
gain ( G.Kt) servo speed is a faithful amplification of Vin divided by a constant. In practice the constant is set by gain resitors or a pot. Note also that to a large
degree the mechanical load on the servo does not affect the speed......the load is counteracted by the feedback. This is an extremely valuable use of feedback.
Using the same basic amplifier the addition of tacho feedback has turned the amplifier into a load independent velocity control unit.
Either of the two amplifier configurations could be used, remember the CSMIO has its own feedback loops enclosing the amp. With sufficient forward loop gain
both work well. Your drive has a personality module in it (it has the gain resistors Kt) and so the manufacturer intended that it be used as in the last pic.
You've found though that if you disconnect the tacho it performs more like the second pic despite having the wrong personality module.
My suggestion is try to digest these pics and what they mean and then we'll try to tune the tacho etc to get it to work as in the last pic. If that's not successful
we may have to revert to the simpler current loop model.
Craig
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Hi All
I'm not too sure how the CSMIO will fit in with torque mode. Certainly the normal assumption is that the CSMIO is followed by a velocity loop, which implies the use of a functioning tacho.
So my inclination would be to first check the tacho and then to try setting RV2 to 10V at the maximum motor speed, as the manual suggests. (At its most basic, the tacho is simply compared with the command to create the error signal at the feedback summing point.) Then adjust RV1 if need be so that the maximum required speed is obtained with a command voltage of 10V.
If the tacho measures OK (which I suspect it will) and the amp still fails after the above procedure, I would assume that the amp is in some way defective.
I wouldn't mess with the other pots as these should be OK. The possible exception is loop stability, but I would leave that alone for now as it would ideally need a signal generator and scope to correctly set it, though the CSMIO could probably be used if need be.
Allan
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Hi Both
Thanks, Craig for the information. It's a little over my head but only had chance to read it once. Will go through it again and absorb. I always like to understand how something works as it makes it so much easier to fix when it goes wrong.
Thanks for the info Allan. The manual says to adjust RV1 first until the motor stops moving at 0v. Then apply max speed 10v and adjust the command gain RV2 until the desired speed is reached. The way I am reading it is RV2 controls the max speed you want not RV1. Please correct me if I am wrong or is the way you're saying a better option?
Cheers
Mick
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Hi,
I'm not too sure how the CSMIO will fit in with torque mode. Certainly the normal assumption is that the CSMIO is followed by a velocity loop, which implies the use of a functioning tacho.
The CSMIO will successfully close a loop with a torque mode amp. When all said and done a velocity loop is just a torque loop with one additional integrator.
The CSMIO already has an integrator and can supply the required gain. With a velocity amp the integral component of the overall loop gain is distributed between
the CSMIO AND the velocity amp whereas the CSMIO supplies all the integral loop gain with a torque mode amp.
Provided there is sufficient stability ( phase margin) that the overall integral gain can be applied the two solutions are dynamically equivalent.
Craig
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Hi,
I would still at least in the first instance follow the procedure in the manual. If the tacho proves good, and as Allan suggests I too think it likely that it is
good, then adjust the taco gain, that is Kt in my pic, so that Vf is nearly equal Vin. That assures a small error, e in my pic, which is the ideal.
I rather suspect that there is a fault with the amplifier part, G in my pic, it should have a very high gain which the feedback loop tames. OPs experiment
of disconnecting the tacho results in sufficient gain where if it were operating normally the forward gain would be excessive.
Craig
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Mick
You are absolutely right, I was working from memory and mixed up RV1 and RV2. It's great that you check over everything as opposed to blindly accepting it.
Craig
Are you sure that it is the Ki rather than the Kd in the CSMIO that provides the equivalent of the tacho feedback? Surely it is Kd that provides the velocity term. (I may be confused as I am writing this after a good lunch with plenty of champagne and red wine.)
Allan
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Hi Allan,
the symbols I've used relate to the pics they are used in, they have no relation to the terminology used by CSMIO.
My intention was to show, in the simplest of terms, the similarities of the two. A proper mathematical description of each
would hopelessly obscure what is was trying to do.
Craig
-
Hi All
Just thinking aloud again. I'm a bit concerned that if we have to run the drive open loop (i.e. without the tacho), its gain might be so high that in order to avoid frequent saturation of the circuits we may have such a small output from the CSMIO that noise becomes an issue. Presumably if the drive were equipped with the torque mode personality module, gain would be tempered by internal passive feedback.
Allan
-
Hi Allan,
yes exactly, if indeed the drive has a velocity mode module fitted the I would have expected the amplifier to saturate almost immediately
the moment Mike opened the tacho feedback loop. From his description he had good control over speed of the servo. This leads me to believe
that the drive is faulty OR, and more likely, wildly mistuned in such a manner that it bears little resemblance to the manufacturers intention.
Craig
-
Hi Both
Thanks for all your input.
One step forward ten steps back. Had 3 hours trying to get somewhere with this.
Checked the voltage from the Tach at full rpm and it puts out around 32v. So went through the process of adjusting RV1. Then RV2 to get my desired RPM. Adjusted the tach to 10v as the controller is putting out. Then totally lost control of the motor. Limit switches, emergency stop and even disconnecting the wires from the command hi Lo would not stop the motor. Had to shut the machine down to stop the motor.
Re-booted mach3 and the controller and the motor fires up again with no command from mach3. Check the voltage on pins 1 and 14 and we have 10v??. Disconnected the wires from pins 1 and 14 and the motor still continues to run. Shutting the machine down is the only way of stopping it. :(
By this point, I am losing my head a little so decided to try plugging the tacho back in and go through the same procedure with tuning. Now it allows me to gain a higher rpm with RV2 although not as high as without the tach. Same problem though the motors spin flat out on power up except this time the limits and emergency stops work. :(
Anyway besides this there are lots of strange things going on.
Sometimes Mach 3 screen jumps to the end of the program as soon as you press start as in a split second.
It sometimes ignores the stop command.
Sometimes If you press the emergency stop the axis on the screen continues going.
icon.DLL defective plugin error pops up when I boot.
INTI.DLL defective plugin error when I boot.
Then sometimes it works perfectly but still get the errors.
I have tried that many things today my head is blown.
Think i'm going to send one of the drives away to get check out. At least then I can rule out the drive. I'll swap the motor over from the Z-axis as well.
You guys have been great. I can't thank you enough for the time you spent with your advise.
Cheers Mick ;)
-
Mick
Are you using Mach3 3.043.062, which is generally said to be the most stable release, with the CSMIO plugin version 2.910?
Have you removed that huge integral term Ki from the CSMIO tuning setup?
Does the motor turn or run away when both command inputs are connected to 0V? If so, it would suggest that the tacho is connected backwards (unlikely). If not, I would connect something like a pot to 10V and see if the drive and motor increase speed and run stably as to adjust the voltage from 0 to 10V. Then reverse polarity and repeat. The point here is to completely exclude the CSMIO until we are sure the drive and motor are working properly.
As a general point of principle, you might consider wiring the drive enable line directly into your emergency stop circuit, so that you are not dependent on any software device to turn off the drive in an emergency.
You have so many issues just now, it's hard to know where to start, but if it were me I'd stick to one device at a time and get it working before connecting everything in a feedback circuit, as this inter-dependence makes it harder to establish where a problem might lie.. If you feel you must use the CSMIO as a signal source, set all coefficients except Kvff to zero, as this will remove any feedback within the CSMIO and allow you to generate independent voltages as if you were using a signal generator.
Allan
-
Hi Mick,
Allan is 100%, the CSMIO and Mach is just distracting you from getting your servo to work.
If you can't get that working properly the ALL BETS ARE OFF. You could take the CSMIO and throw it
over your shoulder for all the difference it will make.
Use a signal generator as Allan has suggested or a 9V battery and a pot.
The runaway problem sounds like the tacho is reversed polarity relative to the servo direction, change one or the
other.
With reference to the last pic I posted, the feedback gain is RV1. The instructions say that you want to have the feedback
voltage Vfb nearly equal to the command input Vin. That assures the the error, e, is small. For a small error to produce
a large current/voltage output requires a high gain G. If you cannot get a high enough output current/voltage despite
having a maximum command input voltage THEN you'll have to back the feeback off, its your only choice.
When the manual says the feedback voltage, Vfb, should be the same as the input voltage, Vin, I think close is better than
exactly the same. If they were exactly the same then the error,e, would be zero and you would not get any output
current/voltage at all! If the input voltage is 10V, make the feedback voltage say 9V. Now try adjusting RV2 to increase
the speed.
If you are thinking about sending one or more drives for repair I'd recommend considering replacing the drive and servo
with a matching modern AC servo/drive. You could bury the original servo and drive in the garden next to the dinosaur grave.
Craig
-
Hi Both
I am using version 3.043.062
Allan, I've tried the Ki on numerous different numbers from 200 up to 50000. Having all the other setting at 0. Totally agree with you about using a 10v pot its a great idea. Should I disconnect the encoder wires from the CSMIO whilst doing that or just turn it off? I presume the servo just needs to be enabled and voltage applied to the Command to get it to move?
Craig LOL. I would love to throw them away with Mach 3 as well and buy a brand new machine. Before I can justify spending thousands on AC servos I need to give these a fair go.
Are you suggesting swapping the phases on the drive as I mentioned the other day or reversing the tacho wires?
Cheers
Mick
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Hi Both
Just thinking, I know its too early but the runaway first occurred when the Tach was not connected. Does this illuminate the possibility of being wired backwards? I have not rewired this, its wired as its always been. As I mentioned before could it be possible that the three-phase going into the drive needs the phases swapping to turn the motor the other way?
There used to be an ATC on this machine which was phase dependent and would only work if the phases were in a particular order.
Cheers
Mick
-
Hi,
Before I can justify spending thousands on AC servos I need to give these a fair go.
Ac servos are not free but they don't cost thousands either.
DMM 200V Off-line Servo and Drive:
750W 200V servo $239
230VAC Drive $218
3m power & encoder cables $71
Total $528
This is for a modern AC servo which will eat the old stuff alive, 16 bit encoder, direct offline power supply, a multitude of control modes including step/direction,
vastly flexible electronic gearing, acceleration and velocity limits, programmable following error, zero error, multiple error reporting modes, indexed position and
velocity and the list goes on.
Note that the servo and drive form the loop, the controller is just a plain (cheap) open loop step/direction source....no closed loop controller required!
Ye-ha! Reduce confusion and tuning problems to a mere nothing! An AC servo and drive is as easy to hook up as a stepper driver, Mach can't tell the
difference between the two.
My experience is that I bought a modern AC servo second hand but have been so impressed I wont consider the old stuff any more.
I know its too early but the runaway first occurred when the Tach was not connected. Does this illuminate the possibility of being wired backwards
No. If it runs with the tach disconnected it just means the amp operates without feedback. Look at the last diagram that I posted.....with the tach disconnected
then the feedback voltage Vfb is zero. Therfore error, e = Vin and the output current would be Iout= Vin.G, given that G is high even a modest input voltage will cause
significant output current and the motor will speed away. That's not faulty, that's just how it works.
If the tacho is connected and there is NO input, ie Vin=0 and the motor speeds away it means that the feedback voltage is generating its own input. This
is called positive feedback and is undesirable. If you reverse EITHER the tacho OR the servo then it becomes negative feedback which is what we want.
As I mentioned before could it be possible that the three-phase going into the drive needs the phases swapping to turn the motor the other way?
No, the three phases are rectified to produce DC. Phase reversal has no effect on the DC output.
Three phase induction motors will reverse the direction of rotation if one of the phases is swapped. If the direction of rotation is important, and it usually is
then attention to phase rotation is required. Your servos should be unaffected by phase reversal.
Totally agree with you about using a 10v pot its a great idea. Should I disconnect the encoder wires from the CSMIO whilst doing that or just turn it off?
For testing purposes 9 or 10V and a pot would be good. Whether the encoder is hooked to the CSMIO is immaterial, the CSMIO might as well be off, we don't need it,
with perhaps the exception of an enable signal, to drive the servo.
Craig
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Mike
Once you have disconnected the 2 command wired to attach your battery and pot, the CMIO cannot affect your measurements, but. The problem you could face is that if the CSMIO has to be enabled in order to enable your drive, the encoder inputs would make it throw a following error as the motor position would no longer correspond to what Mach had commanded. This would disable Mach and your drive. To eliminate this possibility enable your drive directly by connecting 24V to the enable line instead of using CSMIO. (You cannot just disable the motor in Mach as it would no longer activate your enable output.)
Craig
Fully agree. The amp simply balances the scaled tacho output against the scaled command to provide the error signal, and the actual scaling is not critical. As you say, if Mike cannot achieve full speed with 10V at the test point, the only solution, if we are to assume that the amp is otherwise working properly, is to reign back the tacho gain until full speed can be achieved. With any luck it will still be possible to adjust the command gain so that 10V, or something close, is needed at the input to give full speed. It sounds as if the forward gain of the amp is fairly low, which could be by design or because of some component failure. We are confident that the PSU and the tacho are working correctly, but are we sure the motor itself is OK as that could conceivably be a possible cause as it contributes to the loop gain? Mike has said he could swap motors to check this.
Does the DMM support analogue input, or would its use mean replacing the CSMIO as well? I don't see much difference in having the position loop within CSMIO as opposed to within the drive. Either way it needs some adjustment to suit the machine.
Allan
-
Hi Allan,
Does the DMM support analogue input, or would its use mean replacing the CSMIO as well?
Yes DMM servo drives support analogue input and so you could use the CSMIO but that would be crazy. Firstly many of the control features
would now no longer work because the CSMIO closes the loop, not the drive. Secondly DMM make the drive AND the servo and they are perfectly
matched to each other. You can get in there and tune if you wish but you'll have to do really well to better what DMM have done.
I don't see much difference in having the position loop within CSMIO as opposed to within the drive
That's like saying 'my Model T had a crank handle so my new sports car has to have a crank handle too'
Either way it needs some adjustment to suit the machine
You can manually tune the servo drive, although the pre-existing tuning procedures usually mean you don't have to.
Amongst the goodies is a software driven scope which allows you to visualize the adjustments you make in realtime, just so much more advanced
than the CSMIO.
Modern AC servos and drives, of which DMM is an entry level example, are so far advanced over previous methods with far greater flexibility and precision
of control that the CSMIO/A has been rendered obsolete. Do yourself a favour, don't believe me.....buy yourself an example, my preference is Allen Bradley
and prepare to be amazed.
Craig
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Hi Both
Thanks your input again.
Craig thank you for the info on the drives, cheaper than I thought but at the moment will have to persevere with the Norwin drives. I have just spent £700 on the CSMIO with the Threading module.
Right Connected a pot view a 9v Battery with the tach connected.
Adjusted RV1 until motor ceases moving.
Applied 9v via the pot and adjusted RV2 to get max speed.
Turned RV2 back to achieve approx 1000 rpm.
Check Tach voltage which was at 12.3v
Adjusted tach on P/M to 8.9 volts slightly off from the input voltage as Craig suggested.
Turned the pot down to approx 2 volts.
Checked the tach and putting out very similar voltage.
Very positive I think??
Will try connecting the controller up now and see what I get.
Allan Thanks for the tip on the enable going to the emergency stop. I will rewire that.
One thing I noticed when I was adjusting RV1 with 0V applies. By turning the pot a significant amount makes the motor turn one way and turning the pot the other way reversed the motor.
There was a very small millivolt signal but no matter which way the motor turned it was always negative??
Just thought I would mention it.
Can you just clarify something? We keep talking about 0v. I have a red and blue wire coming from the command high low. I have always presumed the red is positive pin 1 on the CSMIO and the blue is negative pin 14 on the CSMIO. Please educate me if needed :D
Cheers Again
Mick
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Hi Mick
Sounds like things are making some sort of sense at last. I think the reversal you have seen could be due to a slight offset error. Although this could be ajusted using the pot on the main PCB, I wouldn't bother as the CSMIO can set the overall offset for you at the press of a button.
Are you able to get a high enough motor speed with 9V input now, and is the motor running smoothly? If speed is still limited I would be inclined (maybe with Craig's approval) to try a small adjustment of RV4 which affects loop gain. Maybe a little iteration of the settings of the 3 pots RV1, RV2, and RV4 would give you the result you require.
I have always presumed the red is positive pin 1 on the CSMIO and the blue is negative pin 14 on the CSMIO.
Yes this is the correct connection. Remember to start with Kd = Ki =Kvff = 0, and gradually increase Kv. Start with Kv = 10 and increase in steps of 10x to maybe 100000. If the motor suddenly runs away, reverse the sense of the encoder feedback and try again. If the motor begins to oscillate, reduce Kv.
It's always safest to have your eStop act directly on the drive enable as well as going independently to the CSMIO so that Mach knows what's going on. At its simplest, you could just add another contact block to your eStop switch and wire this in series with the connection to the drive enable. Some folks use a Piltz (may be incorrectly spelt!) safety relay, but this isn't necessary.
Craig
I doubt if we'll ever agree, but here is my final take on things. The greatest advantage of the matched servo and drive is that the drive has knowledge of all motor parameters. This is especially important in the drive's current loop, less so in the velocity loop, and less again in the position loop. Providing the drive takes care of the current and velocity loops, all that's needed to implement the position loop is encoder feedback and the calculation of a few Z transforms. I'm sure that the fast processor within the CSMIO is perfectly capable of doing that. I use Chinese Kinco drives and servos as you know, and like the DMM these are packed with features and flexibility. I am not aware that any significant features are lost by setting analogue mode and using the IP-A for the position loop. The CSMIO offers all the tuning features you need, including the scope, in its plugin. Don't just take my word for it - you only have to look at posts from folks like Hood to see that the IP-A is capable of excellent results.
Allan
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Hi Both
Thanks, Allan for that. Yes the RPM I have set at around 1000 which gives 5m minute. Done the test and good news and bad news. After setting the drive as described in my earlier post. Exactly the same problem. As soon as I powered the drive the motor runs flat out. Estops working though so no big deal. (Cheers for that tip) Re-booted everything and enabled the drive and the motor runs flat out again. Checked the power at pins 1 and 14 to find 10v again with no command from Mach 3.
Changed command HI Low to pins 2 and 15 channel 1 on the CSMIO and Bingo. Everything works absolutely perfectly. ;D ;D ::) :P
I will keep trying over the next few days to make sure it's not random fix.
Thank you very much for all your time on this and I will report back with feedback over the next few days.
Cheers
Mick
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Mike
Is the analogue drive to the motor you are using mapped to the same channel as the encoder inputs? It sounds like your motor is hooked up to the output of channel 1 but you are taking encoder feedback to channel 0 on the CSMIO. This doesn't matter per se, but it would make things more logical if the two used the same CSMIO channel. Have a look at the plugin settings to see if they are correct.
Allan
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Hi Allan,
the IP-A is capable of excellent results.
That the CSMIO/P-A is capable of great results is not in question, its just that its
not necessary to spend 700 pound to do it.
Mick is struggling to tune his servos, and he is still going up the garden path.....wouldn't happen with good
AC servos.
To Mick:
you should not throttle your servo speed back with RV2. Limiting the axis speed should be done in Machs
motor tuning page. The facility to do it in the drive is for Velocity Never Exceeded imposed by physical plant,
eg lead screw whipping or reduction of over voltage spike on deceleration. Your servo and drive should be tuned for maximium
safe speed and acceleration.
Craig
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Hi Allan,
one situation, which as AC servo technology advances is becoming increasingly common, is serial encoders.
Delta's entry level encoder is 17 bit absolute and 20 bit absolute encoders are an extra. You may have noted that
Seimiens for instance have 23 bit muliturn absolute. Serial encoders will stonker the CSMIO.
The majority of modern AC servo drives have their own motion control built in as befits the emerging
'distributed motion control' paradigm sweeping through industrial CNC with EtherCat be the predominant
communication protocol. Ethercat is not common with Mach users....yet. Make no mistake as time goes on
it will. When that ocurrs our current motion controllers will lose the 'motion control' component and become an
EtherCat master.
Craig
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Hi,
when you think about it servo drives have been getting smarter for many years.
Back in the 70's and 80's all servos were like Mick's. You needed a controller that could close the loop and apply PID dynamics.
In the late 80's digital servo drives became common where the drive could read an encoder and apply PID dynamics. That meant the controller
was not required to close the loop. Gecko 320 is an example of this idea. They work OK but are not particularly sophisticated, certainly not in comparison
to the CSMIO/P-A of our current debate, nor, in comparison to modern AC servo drives either.
In the 90's microprocessor technology had improved to the point that Field Oriented Control was feasible and has advanced rapidly ever since with increasingly
sophisticated control options. More recently still they are in themselves a single axis motion controller, able to apply limits and home autonomously. Strictly speaking
a PC with realtime ethernet you could have a CNC machine without a motion controller at all, just a trajectory planner in the PC and motion control that is distributed amongst
the servo drives.
All of this points to the trend that servos and their matching drives are becoming evermore capable. I guess you might say that manufacturers are taking advantage
of the processing power of microprocessors/FPGAs/DSPs. I think the medium to long term prospects of highly sophisticated and expensive motion control boards
is poor as servo drives take the challenge.
Craig
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Hi Allan
Pins 1 and 14 go to 10v as soon as you power up. I mentioned this before in an earlier post but I think we didn't see it as a problem at the time. I swapped The Command Hi-Low over to Pins 2 and 15 but at the same time changed the DAC output within the CSMIO to channel 1. I think there is a fault with channel 0 in the I/O/? I have done some more tests and everything seems to be working right and very accurate too.
I haven't managed to tune the CSMIO yet. I am struggling to achieve the right KP. If I set the KP at 2000 for instance then autotune, it goes through the process which takes a while. but then resets my KP way up into 40,000's. Run a small program and the machine jumps around. If I reset everything to 0 and leave the KP on around 500 the program runs smoothly. Motors are quiet no jerking etc.
Craig
Was just following the Norwin manual with regards RV2.
Cheers
Mick
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Hi,
Was just following the Norwin manual with regards RV2.
I presume you mean this piece of the manual:
5.3.1 COMMAND GAIN
In some situations it may be necessary to scale down the command signal in order to reduce the
top speed of the motor. This is done by adjusting the potentiometer RV2 on the personality
module.
I contend that limiting the axis speed, as opposed to setting the axis speed in Machs tuning is not what is meant by 'In some situations it may.... '
Craig
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Hi Craig
I will speak to Norwin about it and feedback to you there comments.
Allan/Craig
The motor seems to be working fine now. I have had to manually tune the motor in the CSMIO as the auto-tune feature was giving mad results. Following the manual tune prodecure in the manual didn't really seem to work either apart from adjusting the KP. The kI and KVFF I adjusted by choosing the setting which gave the lowest errors.
The motors are running smoothly and quietly with no jumping at all. Getting accuracy of around 0.02mm on a random program just going back and forth at various speeds.
Thanks for your time and patience on this. Hope I can return the favour at some point. ;)
Cheers
Mick
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Hi all
Good news that the system is now operating, at least at some level.
I am a bit concerned that we are still unsure that the amp and motor are working to specification. The forward gain does seem rather low suggesting the amp or motor may be at fault in some way. The motor can possibly be verified by substitution. We can try adjusting RV4 but ideally need a signal generator and scope to do so. But I think it could be done via the CSMIO scope and I think we could generate the velocity steps via Mach or CSMIO if we use Vff and set all other PID coefficients to zero to eliminate any feedback within the position loop, as this would detract from optimising the amp's velocity loop. Does anyone out there agree with this or have any alternative ideas; or does the system seem responsive enough as it is?
If the velocity loop is too limited in bandwidh, or is Poorly damped, we may have difficulty tuning the position loop, or the overall dynamics may be rather limited. The Kv Mick has achieved seems low to me - when I was using v2.910, admittedly with Mach4, Kv was typically over 100000.
Mick
Thanks for the more detailed explanation of how you have reconnected the encoder and analogue output. I was struggling to see how it could work with the encoder on one axis and the analogue output on another. Haven't personally had any hardware faults but I suppose it is possible. Which axis is the motor on?
Craig
Sure, technology continues to advance, but it will be some time before these changes become common practice in the home shop. Heck, many users still cling to Mach3 despite the superiority of Mach4. They have a system that does what they ask, and that is all they need or desire. Anyway, we need to get back on topic.
Allan
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Hi Allan
The motor is on the X-axis.
Are you still thinking the KP is set at 550 as stated in my last but one post?
Setting the KV in the CSMIO and pressing auto-tune ignores the KP preset and starts again using its own KP gradually increasing it. Then going to the other parameters. I've done it twice now but renders the axis unusable once it's finished.
This is the process I have used to tune the CSMIO.
KP with everything else set to 0: Started with a setting of 500 jogging the motor forward and back. Kept increasing the KP by 500 each time doing the same jogging movements until the motor started jumping around. This started happening at around 28000 KP. So then knocked off around 15% like the manual says and set the KP to 23800.
Ki. Same as KP but increasing in smaller amounts of 10 each time. I got up to around 240 before the motor started jumping around. I knocked off 15% and set the KI to 200.
KVff: I couldn't really see any huge difference with motor movement but there was a large difference in the error counts. I found a point when adjusting it either way, started to increase the error rate.
This was found at 172 KVff
So the settings in the CSMIO are as follows.
Kp: 23800
KI: 200
KD: 0
KVff: 171
The motor seems to be running fine on rapid and slow moves Allan but if these setting seem odd or not right I am happy to try and improve them.
Cheers
Mick
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Hi,
The forward gain does seem rather low suggesting the amp or motor may be at fault in some way
I agree, I'm of the opinion that the velocity loop is still a long way short of where it could and should be.
Consequently the CSMIO tuning just makes the best of what is rather than the best of which it is capable.
Describing the tuning process has not been effective, and a signal generator/scope is indicated. In absence of that then
the performance of OPs current settings will have to be deemed adequate.
Craig
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Hi Craig
I am happy to try and tune differently to what I have already. Will it improve what it's doing now?
Cheers
Mick
-
Hi All
Mick, I did think you still had Kp set at 550. I cannot fault the way you have attempted to optimise tuning of the CSMIO, and if you feel that the axis is performing as well as it originally did, and/or are satisfied with it, so be it.
Out of interest, did you get the CSMIO scope to work, or did you just use the figure for following error? The scope would allow you to see how fast the axis reacts to a step change, and how well damped the resulting transients are.
Like Craig, however, I feel that the velocity loop is weak and this may well be what is preventing the auto-tune completing sensibly as well as rendering your overall manual tune sub-optimal. If you feel inclined to push for better performance, this is the area that I feel needs your attention. You will need a scope, or as I have suggested you could probably use the CSMIO scope if you don't possess one. But if you proceed, do take care not to invoke the position loop as well. You would tune that, repeating the process you've already carried out, after you had optimised the velocity loop. Either use a signal generator to feed the command inputs, or if that is not available, try using Vff (only) with CSMIO as I suggested earlier.
Best of luck if you proceed with it. It might be wise to mark the original position of RV4 just in case you have to revert to the status quo.
Allan
-
Hi Mick,
if and how much improvement could be had is at best a wild guess, I would say that you could improve the
underlying servo velocity loop by 50%.
Given that you have followed written instruction only I think you have achieved a good result. To do better
you will need a scope and sig-gen to inform your tuning. While you could use the CSMIO scope and Mach/CSMIO
as a signal source I suspect the confusion that it would generate would make any gains difficult.
If I were doing it I would use my signal generator to produce a step signal, actually a 10V amplitude square wave
of period 10sec, and observe the error with the scope. I would be looking to improve the speed of response
with a 9% overshoot (sometimes called the Gibbs overshoot). RV2 would be left wide open. The tuning would be
principally done with RV1 (tacho gain) and RV4 (stability). Thereafter I would use my signal generator to produce a sine
wave and measure and plot the Bode frequency response and therefore deduce the gain and phase margins.
Does any of that sound familiar to you? If not then I suspect trying to do it by forum post will drive you up the wall!
I think your existing solution is good enough. You might in time come back and revisit it but I would suggest you move on
to other matters and make some chips.....
All in all I think you are to be congratulated on the result you have achieved given your unfamiliarity of feedback
control systems.
Craig
-
All in all I think you are to be congratulated on the result you have achieved given your unfamiliarity of feedback
control systems.
Absolutely agreed.
Allan
-
Hi Craig/ Allan
No, I have not got a signal generator. I used the follow error in the CSMIO. I think I need to get on with the rest of the conversion for now. I can't see any difference now to what they were before, as far as the motor performance. That being said I would like to be in a position to be able to tune the whole system accurately.
What would I need as far as a scope is concerned? I have an Arduino which is capable of becoming a scope or is that ridiculous? Some of what you are saying in the last couple of posts is going over my head a little so please try and explain in laymen terms.
Really pleased where we are now and thank you for all the support.
Cheers
Mick
-
Hi Mick,
in recent years entry level PC based oscilloscopes have become very very much cheaper and yes something like an Arduino could be pressed into
service. The technical requirements for an oscilloscope for tuning servos is fairly modest and you could very easily get a highly useful PC based instrument
for less than 100 pound, such instruments will often have a built in programmable signal generator.
I may do a little searching around and try to make some sensible recommendations for you.
Even with a suitable instrument you will have to learn to use it and then learn to apply the information obtained from its use to tune your servos.
That is not for the faint hearted, to make sense of things you will be required to be absolutely familiar with diagrams of the type I posted earlier.
Not only will you have to understand them but do some basic calculations with the data obtained.
Depending on your inclination it could be a fascinating learning experience which you may enjoy.....well within the parameters of a challenging and rewarding
hobby......or it could put you off for life!!
Craig
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Hi Craig
Sounds good. Do love a bit of Math so let me know your thoughts on a suitable scope.
Cheers
Mick
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Hi Mick,
just blown away at the range of whats available....this caught my eye....Velleman is a genuine US instrument maker and I used Velleman before
when I worked at an automotive garage. I don't mean to say that there are not other brands and cheaper stuff....its just I trust this one:
https://www.ebay.com/itm/Velleman-PCSU200-USB-PC-Oscilloscope-and-Signal-Generator/112196139443?epid=13011370657&hash=item1a1f6939b3%3Ag%3AKQ8AAOSwKOJYH17u%3Asc%3AShippingMethodStandard%2197203%21US%21-1&_sacat=0&_nkw=usb+oscilloscope+and+signal+generator&_from=R40&rt=nc&LH_TitleDesc=0 (https://www.ebay.com/itm/Velleman-PCSU200-USB-PC-Oscilloscope-and-Signal-Generator/112196139443?epid=13011370657&hash=item1a1f6939b3%3Ag%3AKQ8AAOSwKOJYH17u%3Asc%3AShippingMethodStandard%2197203%21US%21-1&_sacat=0&_nkw=usb+oscilloscope+and+signal+generator&_from=R40&rt=nc&LH_TitleDesc=0)
Craig
-
Thanks Craig
I will have a look into it but want to complete the conversion first. Will be looking at the spindle and drive next week. I'm sure I'll get stuck again. LOL
Appreciate your time on this.
Cheers
Mick
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Hi,
most of the combined scope/signal generators have a minimum frequency of 1Hz or more which is too fast for testing servos.
This cheap ($20US) and cheerful signal generator might be more useful, it can go down to 0.01Hz:
https://www.ebay.com/itm/0-01Hz-5MHz-DDS-Function-Signal-Generator-Module-Custom-arbitrary-Waveform/292601759815?hash=item44206c8847%3Ag%3Ah78AAOSwgTJbIFCm&_sacat=0&_nkw=dds+signal+generator&_from=R40&rt=nc&_trksid=p2060353.m570.l1311.R1.TR8.TRC1.A0.H1.Xdds+signa.TRS0 (https://www.ebay.com/itm/0-01Hz-5MHz-DDS-Function-Signal-Generator-Module-Custom-arbitrary-Waveform/292601759815?hash=item44206c8847%3Ag%3Ah78AAOSwgTJbIFCm&_sacat=0&_nkw=dds+signal+generator&_from=R40&rt=nc&_trksid=p2060353.m570.l1311.R1.TR8.TRC1.A0.H1.Xdds+signa.TRS0)
If you went this way then you could choose from a multitude of two channel scopes, many for very much less than the Velleman I linked to earlier
on the basis of two scope input channels AND a signal generator. For example:
https://www.ebay.com/itm/Hantek-6022BE-20MHz-48MSa-s-Handheld-2-CH-PC-USB-Digital-Storage-Oscilloscope/122988824398?hash=item1ca2b4874e%3Ag%3ALxgAAOSwaeFak8VY&_sacat=0&_nkw=usb+oscilloscope&_from=R40&rt=nc&LH_TitleDesc=0 (https://www.ebay.com/itm/Hantek-6022BE-20MHz-48MSa-s-Handheld-2-CH-PC-USB-Digital-Storage-Oscilloscope/122988824398?hash=item1ca2b4874e%3Ag%3ALxgAAOSwaeFak8VY&_sacat=0&_nkw=usb+oscilloscope&_from=R40&rt=nc&LH_TitleDesc=0)
Craig
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Hi Craig
Thanks for the info. Definitely worth buying one at that price.
Allan/ Craig
Probably needs a new topic but would you have any idea where to start with the wiring on this spindle encoder? I can't see any information on it but has 8 wires coming out.
Also, I am trying to identify what is attached to the back of the spindle. It looks like some kind of air pump which is attached to a fork that moves in and out. I have never used it and I did ask Denford what it was a few years ago who didn't know. Please see images.
Cheers
Mick
-
Hi Allan/ Craig
The CSMIO has a max voltage input of 10v on the Analog I/0. I found channel 0 to be faulty putting out 10v continuously. The tacho for the motors puts out about 9v per 1000rpm. Does this mean until the tacho output voltage was adjusted to match the command voltage there was potentially approx 27v being fed into the CSMIO (At 3000rpm). Possibly causing the failure of Channel 0.
The only reason I ask is I am about to set up the Z axis and thinking maybe disconnect the Tacho wires from the CSMIO until the tacho output is matched to the command input?
Cheers
Mick
-
Sorry meant disconnect tach from the drive. :D
-
Hi Mick
No, I don't think this is at all likely. The tacho and the command input are isolated from each other as both feed via resistors into a summing junction of an op amp if I remember correctly. This summing junction is a low impedance input. The command input is further isolated by the input differential amplifier.
Allan
-
Thanks Allan
Appreciate your help again.
Mick
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Hi Allan
Sorry to bother you again. I set up my Z axis and was working fine until today when the drive decided not to enable. Do you think its worth spending money on these drives as they are 30 years old? I have found a company that can supply some new 20amp analogue drives cheaper than it was to repair the Norwin ones a couple of years ago. They have checked the specs of the Norwin drives and Sem motors and advise they will work fine.
The drives do not do tacho feedback though. Is this a major issue? It's so frustrating doing a retrofit and sometimes wonder whether to just spend the money on a new machine.
Cheers
Mick
-
Hi Mick
You are certainly having some bad luck.
As you know, both Craig and I are converts to ac servos, and without doubt that would be the ideal solution if money needs to be spent. But I appreciate that this would involve greater expense and more work, both electrical and mechanical, than simply replacing the analogue drive.
As to the suggested analogue alternatives, I'm not sure that the lack of tacho feedback would matter greatly. The tacho integrates motor torque to provide velocity feedback which effectively makes the motor speed proportional to the voltage applied at the command input. An equivalent function could be provided within the new drive, for example by taking feedback from the armature voltage. The same function can be provided by the Kd term within CSMIO. Crudely speaking, all these options boil down to the same thing in the end. In practice, you will probably need some re-tuning of the PID loop but I cannot see why you should not expect an acceptable performance if the drives have a similar specification.
Allan
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Hi Allan
I will have a read up on what the KD does in the CSMIO and try and get my head around it. Good to know there are options available without replacing the motors.
Thanks for your time again.
Cheers
Mick
-
Hi,
I made this same argument earlier in this thread, whether you have a tacho loop in addition to the CSMIO loop or just the CSMIO loop the
net result is the same. Clearly the PID coefficients will differ but both will achieve dynamic equivalence.
You are now really starting to pay for your choice to retain the existing servos. You paid a premium for an analogue controller to close the loop,
700GBP= 915USD. You are now looking at more cost to repair or replace your servo drive which takes the spend to just over $1000.
If you had replaced the servos with AC servos and drives you could have used an open loop Step/Direction controller like a UC300
or an ESS for $150-$180. Two 750W DMM servos and drives are $1052, taking the total spend to about $1200.
New and modern AC servos/drives are so superior in so many ways.
I am of the opinion that spending more money on your existing servos or drives is a case of 'sending good money after bad'.
Craig
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Hi Craig
Thank for confirming that we can do without the feedback from the motors. I appreciate that you had said this before but please forgive me as I am not anywhere near up to speed with PID loops, servos systems etc. This is something I intend to get more familiar with as I believe you can fix anything if you know how it works.
As far as the CSMIO goes Hindsight is a wonderful thing. The lathe came from a Rolls Royce training facility and had only done 800 hours.
The CSMIO cost me £500 as I can reclaim the Vat and I have just had costings to repair the drive from Norwin for £75. Or I can replace the drives for £100 each.
So my spend so far is £575 or £700 with new drives.
The reasons I chose the CSMIO is because it is well respected by loads of very knowledgeable people on the forum and is distributed throughout the Uk by several CNC specialists.
It also has the ability to deal with threading which in my experience is difficult to get right with Mach 3.
Changing the servos would also mean that additional power supplies would be needed. Mounting plates would also have to be made and belts replaced. Then you have the issue of matching the new servos to the old ones as far as torque etc. Are the servos you've mentioned equivalent to what I would be taking off?
If this is the wrong route I will replace the drives and Motors with new. Not something I want to do just yet but if I do, someone at some point will be looking for that particular servo motor and pay good money for it.
Cheers
Mick
-
Mick
Sounds like the repair is your cheapest option, at least in the short term.
I'm not sure if you realise that ac servo drives would typically be mains powered, so would not require a complex power chassis like the one you currently use. You would only need a +24V logic supply for the CSMIO and the drive logic circuits. Drives can be programmed for either analogue +/-10V or step and direction inputs. The former would allow you to use the CSMIO that you already have. I personally prefer the screened construction and 24V logic of the CSMIO to the bare board presentation and 5V levels of the cheaper alternatives.
Allan
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Hi Allan
Thanks for that info and great to know I can still use the CSMIO. I have emailed Norwin and asked them to repair the drive anyway. I can't sell a drive that doesn't work. Yes, I agree that the CSMIO is an industry standard 24v controller that is not open to the elements which is another reason I liked it.
If I decided to go down the AC route what drivers and motors would be a good choice? Craig has mentioned some possibilities in previous posts and I will look into those over the next few days.
Cheers
Mick
-
Mick
If you ultimately switch to ac drives, one thing is very important: use matched drives and motors from the same manufacturer. In that way, the drive will be pre-programmed with all of the salient motor parameters.
I have found the Chinese Kinko drives to be of good quality, well designed and reliable. I use their CD422A drives, which can be paired with servos up to 750W. Motors are equipped with decent circular connectors and good quality cables of 3m and 5m lengths are available for this connection. These drives are very flexible and can be programmed either from their panel or via a free PC application. One caveat: you need to be adept at fine soldering as there is a minature 36 pin I/O connector that needs to be soldered.
Allan
-
Hi,
If you ultimately switch to ac drives, one thing is very important: use matched drives and motors from the same manufacturer. In that way, the drive will be pre-programmed with all of the salient motor parameters.
So true, my Allen Bradley servo has a PC apllication that loads the servo data straight into the drive, it has all the
usual resistances and inductances but also has a peicewise linear approximation to the magnetic hysteresis properties
and also includes a thermal model......just brill! They are SO FAR AHEAD of brushed servos it just has to be experienced to
be believed.
Craig
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Hi,
if you are going to continue to use the CSMIO-A as controller then the CSMIO MUST read the encoder
to close the position loop, therefore any servo that has a serial encoder will not work with the CSMIO.
As it turns out there are still plenty of servos with quadrature incremental encoders out there, 2500 line
or 10,000 count is entry level these days. The DMM's I alluded to have a 16 bit incremental and would work
with the CSMIO. Not sure about the Delta 17 bit encoders and even less sure about Delta's 20 bit absolute
encoders. Quite frankly the trend to serial multi turn encoders is already underway...I think in ten years time you'll
only find incremental encoders on old plant.
As I have already said in this thread; servo drives are becoming increasingly sophisticated and closed loop
capable motion controllers are falling by the wayside.
Craig
-
Hi Both
Thanks for all the info. I will work some costing out for both drives. As far as sizing the motors to what I have. The specs in the manual for the Sem motors doesn't give any KW rating. If I go off the motor plate its states at 130v the motor will turn at 4000rpm and demand 37amp.
This works out to 4.8kw?????? Surely my calculations are not right. When the motors we are talking about are around 700 watts.
Allan
Where did you buy the Kinko drives.? Are you using Kinko Motors?
Cheers
Mick
-
Hi Mick,
Where did you buy the Kinko drives.? Are you using Kinko Motors?
That is exactly what Allan commented about....the desirability that the servo and drive be from the same manufacturer and matched.
There are drives, Granite Drives for one, that are intended to be applied to a range of servos and they do a good job. I doubt they could ever match
a drive and motor from the same manufacturer/ design team.
Craig
-
Hi,
I suspect that the peak power might be 4.8kW but a continuous power of 1/4 or less, about 900W.
A 750W or 1kW AC servo would be a good match.
Craig
-
Hi Craig
Are you using an Allen Bradley motor to match your drive?
Cheers
Mick
-
Mick
I purchased the Kinco drives and motors from Zap Automation in the UK.
Allan
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Hi Mick,
Are you using an Allen Bradley motor to match your drive?
Yes, emphatically yes.
Craig
-
Hi Mick,
I notice the Kinco motors in 1kW are 130mm frame, might pay to check they will fit in.
Also they are slower, one 5Nm@2000rpm and the other 10Nm@1000 rpm.
Note also that Kinco do 20 bit absolute encoders which I don't think will be compatible with the CSMIO,
choose the model carefully or you will end up having to replace the analogue controller with a step/direction unit whether
you like it or not.
Craig.
-
Hi Mick,
you might also consider second hand, thats how I got my servo. I got it, 1.8kW and matching
DSD020 drive for $800NZD, about $550US, including freight. Note this unit was already in New Zealand
otherwise the freight could have been another $150US. I had to buy/make the cables, not insubtantial,
don't overlook them if you are buying. Good cables and connectors are essential and good ones aren't cheap.
This thing does 6.2Nm continous at 3500rpm and can position to less than 5 arc min and accelerate to 3500rpm
from standstill in under 2 sec. Its almost too good for a mere spindle motor but I wanted the torque and AC servos
are about the highest 'torque density' out there. I can bury a 16mm four flute mill tool in 316 stainless to the extent
my machine flexes before the servo stalls. It KICKS ANUS!!!
Craig
-
.......
Note also that Kinco do 20 bit absolute encoders which I don't think will be compatible with the CSMIO,
choose the model carefully or you will end up having to replace the analogue controller with a step/direction unit whether
you like it or not.
Craig.
That probably won't matter as the drives will have emulated outputs which are compatible, same as the Telemecanique drives I use on the Chiron, encoders are Sine/Cosine but feedback output from the drive is standard A B Z. In fact your Allen Bradleys do the same, quite a few of the AB motors I use are Sine/Cosine and the dives can output A B Z.
-
Welcome back Hood.
-
Thanks Craig for the info.
Hood
What Telemecanique drives are you using? The reason I ask is my wife works for Schneider Electric and we can buy any of there products at cost.
Cheers
Mick
-
Hi,
I work in he electrical industry and have been offered Schneider Electric drives, probably not at cost but at a great discount on the list price.
They look like great units but are still two and three times more than Delta and DMM.
The sad reality is that US, European and Japanese drives are very expensive, even second hand are still more than Delta and DMM are new.
Great to hear from you Hood. I seem to recall that there was a bloody big golf game in your neck of the woods last week.....you didn't get hit on the head
with a golf ball did you? ;)
Craig
-
Thanks Tweakie but just temporarily back, possibly be in now and then.
Mick
They are Lexium 05's but when I bought them second hand (only a few hours at most powered time) they were already a discontinued model. I think the Lexium 32's took over from them.
Craig
PITA, roads all closed, no parking etc etc, glad I live at he opposite end of town and doubly glad it has finished.
-
Hi All
Thanks Hood.
Just been looking at the Lexium 28 with BCH2 motors from Telemecanique.
I can get this 1kw drive for £221 inc vat. https://uk.rs-online.com/web/p/servo-drives-controls/1110812/
The 750w servo motors for £138.00 inc vat https://uk.rs-online.com/web/p/servo-motors/1110822/?sra=pmpn
I think its a no-brainer really as far as switching to Ac servos.
Craig
You suggested in your previous post my Sem motors were probably rated at around 900watts continuous. Could you have a look at the link above to see if you think that particular motor may be suitable?
Cheers
Mick
-
I don't recall the motor details but SEM DC servos are usually around 2-2500rpm so if that is the case and I reckoned they were about 900 watt then that would mean continuous torque torque would be about 3.5-4Nm.
The motors linked are 750W so down on power but if you geared them so as to be around the same max rpm as the SEM then the torque would be getting close, Also you have huge overheads for short times with AC servos so yes I think they should be ok.
-
Hi Hood
I can go up to a 1kw motor as it won't make much difference on the price. If so should the drive be increased to the 1.5kw or is it ok to use the same size drive. I have attached a picture of the Sem motor plate.
Great to hear from you again.
Cheers
Mick
-
I would say that if you can get 1Kw for not much more then it would be better.
Just looked at the specs of the drives/motors and the one you linked to earlier is actually 5000rpm max but only rated 3000 rpm so you probably wouldn't be able to gear it too much in comparison to the original.
It would depend however what the original was actually supplied, voltage wise, from the Norwin drives, it may have just been 90v which would mean approx 2000rpm would have been the normal max rpm of the motor on the lathe.
As said I just looked at the specs and that drive can handle 1KW motors so it would be fine, they show three that are compatible. Just different inertias, I would probably opt for the medium inertia myself.
-
Hi Mick,
the prices you quoted for Schneider units are considerably better than is obtainable in New Zealand.
I think the critical number in the pic of your existing servos is the continuous rated torque. Provided any servo that you choose can match
or exceed that then the machine will have all the grunt that the manufacturer intended. It may well be that you can find a servo of even greater
torque but at a lower speed. You could as Hood suggests gear it suit and make the match near perfect OR accept that your machine in hobby
service may be somewhat slower than it was.
If you do the calculation it may prove that the maximum axis speed of the by using the max servo speed is ridiculously high anyway. In production
machines where cycle time is critical acceleration (read torque) figures as highly as maximum speed (read rated motor rpm), if anything slightly
more torque would prove more satisfying with respect to following accuracy than high speed.
That you are investigating AC servos and coming to the conclusion that they can be had if, not cheaply, at least affordably will allow you to advance
your project very considerably and in a very satisfying manner, AC servos will eat the SEM's for breakfast.
Craig
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Hi,
the power calculation:
angular frequency (radians/sec) =4000 X PI X 2 / 60
=410.9 rad/sec
Power= torque X angular frequency
=2.1 X 410.9
= 879.6 W
As a double check:
Power = Voltage X Current
=130 X 6.8
=884 W
My contention that a 750W servo would suffice seems correct, if you can get 1kW or greater servos for the same money then why not?
I think 1 horsepower axis motors should be ANY AMOUNT for a hobby machine as it is!
Craig
-
Hood Craig
Thank you for your time again. Definitely gonna go for the AC servos and drives.
Craig
Great explanation of how you got to the 900watts. This makes much more sense now!
Can't believe the resolution on the modern encoders.
I can see what you mean now when you said 10,000 line was entry level.
Cheers
Mick
-
Hi,
in some respects resolution beyond 10,000 count is beyond the mechanical accuracy of our machines
and is of academic interest.
However multiturn absolute encoders are increasingly common and with a little battery pack don't lose
position when depowered. With a 24 bit encoder such as the Delta A3 series you could have 8 bits for
complete revolutions, ie +127 and -128 revolutions and still have 16 bit resolution within any one revolution,
that is 1:65536 or 0.32 arc min. Enough for any purpose I would have thought!
Craig
-
Hi Hood
The Norwin Drives were putting 108v to the motors. The max speed according to the Denford Manual was 5M Minute and ball screws have a 5mm pitch. Where did you find the info from the screenshot? I can't find some of those part numbers.
Cheers
Mick
-
108V would be in the region of 2500rpm on the motor, 5m/min with 5mm pitch would be 1000rpm on the screw so sounds like the motor gearing is 2.5:1 at the moment.
Page 26 of the manual from Schneiders site.
http://download.schneider-electric.com/files?p_enDocType=User%20guide&p_File_Name=LXM28A_Manual_V2.1_EN.pdf&p_Doc_Ref=0198441114054-EN&_ga=2.219455582.630719219.1533230045-1043352968.1533230045
-
Hi Hood
Thanks for the link. We have no gearing on the motors. It's 1:1 ratio. I presume the OT control restricted the max rpm to limit the axis speed to 5m Min I have a slight problem with the BCH2MM102∙C∙6C motor as the flange size is too big for the X-axis. I could get it to fit on the Z axis but still a bit tight.
If I use the BCH2LF073∙C∙5C or the BCH2LF073∙C∙5C and gear down 2:1 I believe this will double the torque? Which would be above the Sem motors as you suggested in a previous post. That will give me an axis speed of 7.5 M min well above what I require. Does that sound about right or would you suggest something different?
I have noticed there is only an option for the High and Low inertia on that motor. What would be the better option?
Cheers
Mick
-
Hi,
how do you intend on gearing it?
Low lash planetary gearboxes are worth as much as a servo.
If I read correctly the servo you are looking at (BCH2.F) has an 80mm frame and a bolt hole pitch circle of 90mm, is this correct?
The SEM you are replacing is an MT30, correct? If that's the case then the motor is 110mm in diameter and the pitch circle of the
bolts is 75mm. Is this correct?
The BCh2.H has a 100mm frame and a pitch circle of 115mm, would that not be a closer physical fit?
I would be trying to couple in directly, no gearing.
Craig
-
Hi Craig
I was going to use a smaller sprocket on the motor. They are belt driven at the moment.
The two motors I was referring to will fit no problem. Just need to get a plate made. The motor I was going to get was a 1kw BCH2MM102∙C∙6C. The Circle diameter of the mounting holes is 145mm. Which will not be a pretty fit on the x-axis.
I think we have established that motors BCH2LF073∙C∙5C or the BCH2LF073∙C∙5C are close to spec but Hood suggested slightly underpowered. Hence why I was thinking of gearing down as I don't need 3000 rpm on rapids.
I can send you links to the motors if you wish.
Cheers
Mick
-
Hi,
https://www.ebay.com/itm/Allen-Bradley-Servo-Motor-MPL-A320P-SK24AA/192613875014?hash=item2cd8ae7d46%3Ag%3AP4YAAOSwL2NahrO3&_sacat=0&_nkw=mpl+a320&_from=R40&rt=nc&_trksid=m570.l1313 (https://www.ebay.com/itm/Allen-Bradley-Servo-Motor-MPL-A320P-SK24AA/192613875014?hash=item2cd8ae7d46%3Ag%3AP4YAAOSwL2NahrO3&_sacat=0&_nkw=mpl+a320&_from=R40&rt=nc&_trksid=m570.l1313)
100mm frame, 115 pitch circle, 3.05Nm cont stall, 5000rpm for $195.
https://www.ebay.com/itm/ALLEN-BRADLEY-2098-DSD-020-SERIES-C-ULTRA-3000-DIGITAL-SERVO-DRIVE-2098DSD020/123164628776?epid=1601526528&hash=item1cad2f1728%3Ag%3A0BIAAOSwJslbEEF9&_sacat=0&_nkw=Allen+Bradley+2098-dsd+020&_from=R40&rt=nc&_trksid=p2323847.m570.l1312.R3.TR0.TRC0.A0.H0.TRS5 (https://www.ebay.com/itm/ALLEN-BRADLEY-2098-DSD-020-SERIES-C-ULTRA-3000-DIGITAL-SERVO-DRIVE-2098DSD020/123164628776?epid=1601526528&hash=item1cad2f1728%3Ag%3A0BIAAOSwJslbEEF9&_sacat=0&_nkw=Allen+Bradley+2098-dsd+020&_from=R40&rt=nc&_trksid=p2323847.m570.l1312.R3.TR0.TRC0.A0.H0.TRS5)
and matching drive for $160.
Craig
-
Hi,
when I read the spec of the BCH2.F I saw a continuous torque of 2.39Nm which is slightly more than the SEM's you are replacing.
That's plenty.....you will never even get close to absorbing the power that servo can produce....underpowered! :o
Remember also that power is torque times speed. Even without changing the gearing the BCH2.F will have more power right throughout its
rev range up to 3000 rpm, thereafter the SEM nudges ahead. Will you ever get close to 3000 rpm? 1:1 on 5mm pitch screws is 15m/min,
so not even close.
We have a customer who has an oldish twin column Okuma CNC, its freaking GINORMUS, and its Y axis motor is 1hp. It lunks around the
main spindle which is 50hp and weighs 1/2 a ton or more.
A 1hp axis motor will drive your lathe within an inch of its life!. You would still end up with a satisfying build by gearing down 200W servos,
you might start to notice the reduction in rapid traverse but you wouldn't see much difference otherwise.
Craig
-
Hi Craig
Thanks for the links but makes no sense to me to buy used motors when I can get branded stuff at such a great price.
Think I will definitely go for the smaller motors and yes I don't need 15m/min, half that is plenty. What are your thoughts on the two different models? High and low inertia. I have tried reading up on it but a little bit over my head.
Cheers
Mick
-
Just read the last few posts. My assumption on the SEMs was they were 900w at 2-2500 rpm but the pic shows it is 4000rpm.
The 750W Schneiders on RS said 5000rpm but I now see that is Max RPM and rated is 3000 and so 750w at rated so yes the Schneiders are both more powerful and have more torque than the SEM in the range you will be using them. The SEM would be about 670w at 3000rpm.
I will see if I can dig up a Torque curve for the SEMs but usually the torque starts to drop off on these motors around about 1-1500rpm where AC servos it tends to stay constant right up to rated RPM.
.
-
Ok here are the curves for both SEM and Schneider.
The SEM starts to drop off at 1000rpm and at 3000rpm it is probably around 1.5Nm where the Schneider doesn't tail off until the rated rpm of 3000.
-
Ah, SEM one didn't load, hopefully it is attached now.
-
Hi,
https://www.ebay.com/itm/Allen-Bradley-Servo-Motor-MPL-A320P-SK24AA/192613875014?hash=item2cd8ae7d46%3Ag%3AP4YAAOSwL2NahrO3&_sacat=0&_nkw=mpl+a320&_from=R40&rt=nc&_trksid=m570.l1313 (https://www.ebay.com/itm/Allen-Bradley-Servo-Motor-MPL-A320P-SK24AA/192613875014?hash=item2cd8ae7d46%3Ag%3AP4YAAOSwL2NahrO3&_sacat=0&_nkw=mpl+a320&_from=R40&rt=nc&_trksid=m570.l1313)
100mm frame, 115 pitch circle, 3.05Nm cont stall, 5000rpm for $195.
https://www.ebay.com/itm/ALLEN-BRADLEY-2098-DSD-020-SERIES-C-ULTRA-3000-DIGITAL-SERVO-DRIVE-2098DSD020/123164628776?epid=1601526528&hash=item1cad2f1728%3Ag%3A0BIAAOSwJslbEEF9&_sacat=0&_nkw=Allen+Bradley+2098-dsd+020&_from=R40&rt=nc&_trksid=p2323847.m570.l1312.R3.TR0.TRC0.A0.H0.TRS5 (https://www.ebay.com/itm/ALLEN-BRADLEY-2098-DSD-020-SERIES-C-ULTRA-3000-DIGITAL-SERVO-DRIVE-2098DSD020/123164628776?epid=1601526528&hash=item1cad2f1728%3Ag%3A0BIAAOSwJslbEEF9&_sacat=0&_nkw=Allen+Bradley+2098-dsd+020&_from=R40&rt=nc&_trksid=p2323847.m570.l1312.R3.TR0.TRC0.A0.H0.TRS5)
and matching drive for $160.
Craig
Had these motors on the Bridgeport, friend now has them on his Avon Mill. Good motors.
-
Hood
Thanks for the detailed explanation and time taken. I have got all this info but hard to syphon through with lack of experience. What would be a better choice the high or low inertia?
Cheers
Mick
-
Not sure what it is going on without reading back, think a lathe but unsure the size. As mentioned above I had the MPL motors on a Bridgeport and they are now on a slightly larger mill and they do fine, they are Low inertia (the L in MPL)
It is obviously not a massive lathe going by the original motors so likely the low inertia will be fine. For a definitive answer you would really need to work out the inertia ratio, there are online calculators to do that if you feel the need.
-
Cheers Hood
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Hi Mick,
Thanks for the links but makes no sense to me to buy used motors when I can get branded stuff at such a great price
COST. If I were to buy new, admitting that the drive has now been superseded, I would have had to shell out over $4000NZD for my MPL-A430H
and 2098-DSD-020 drive.
I agree that because you can buy Schnieder at such a good price then new makes sense, if you were paying list price or even with a good trade discount
on the list price (which is basically what I was offered by one of our electrical suppliers) they are still beyond my means.
My experience is that the only wearing parts of a an AC servo is the bearings. My servo came from a carpet factory, I don't know how much work its done,
but it hasn't 'worn' per se. If anything I would be more suspect of a secondhand drive, they are fairly high strung units. As you know electronics devices
don't wear in the same manner as mechanical devices, having said that it will 'let go' at some time. Allen Bradley is a superb brand and I do not expect their
device to have any design weaknesses. Fortunately these particular drives are very plentiful on EBay and very reasonably priced if being selective even should
it 'go South' on me.
As it turns out that this secondhand unit, by the time I bought/made the cables and bought the setup software worked out about the same price as a new
Delta of the same power. Hence my recommendation to pay attention to the availability of cables and the price. Likewise I ended up buying from
our local Rockwell Automation distributor the setup software, cost $200NZD or about $120US. While I might have got a new Delta for the same money
I am very happy with the Allen Bradley, I've knocked up about 500hrs on it so far. Additionally the learning experience I got from perusing manufacturers
data, searching for secondhand units, making my own spindle complete with angular contact bearings and RegoFix toolholder has been worth any premium.
Craig
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Hi Craig
These motors do look good if not better than the Schneider ones but with Schneider only being 30 minutes from me and probably being able to get better support as they are new, I will go for the Schneider ones.
They will be more than enough for what I need and like you said a massive improvement on the DC drives. I will order the cables with the drives as suggested.
Slightly off topic, I have a huge 5.5kw spindle motor on the lathe at the moment. It's 30-year old which may explain the size. It's a three-phase motor which is a pain to be honest as I have to run it off a 3 phase digital inverter which cost me £1200 a couple of years ago. Would really like to have everything single phase and thinking of maybe using a servo on the spindle which would allow a fourth axis at some point. The Schneider single phase servos only go up to 1.5kw and 2000rpm. Is this a not starter if not using 3 phase?
I have attached a picture of the motor plate.
Cheers
Mick
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Likewise I ended up buying from
our local Rockwell Automation distributor the setup software, cost $200NZD or about $120US.
Why did you buy the software? it is available as a free download or at least it was.
Slightly off topic, I have a huge 5.5kw spindle motor on the lathe at the moment. It's 30-year old which may explain the size. It's a three-phase motor which is a pain to be honest as I have to run it off a 3 phase digital inverter which cost me £1200 a couple of years ago. Would really like to have everything single phase and thinking of maybe using a servo on the spindle which would allow a fourth axis at some point. The Schneider single phase servos only go up to 1.5kw and 2000rpm. Is this a not starter if not using 3 phase?
I have attached a picture of the motor plate.
Cheers
Mick
3Kw drives are probably about the biggest you are going to get on single phase, whether that will be big enough or not will I suppose depend on how your original motor worked. It may be a proper spindle motor driven via a proper spindle drive which tends to do better than a standard 3 phase AC motor and a VFD.
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Hood
The motor is original I think which is capable of 6000 rpm at 205hz. The VFD was a cd500 which I replaced with a Jaguar VXM 550 when it gave up. Just thinking ahead really. Would be nice just to get the new AC axis drives installed and working as they should. Then look at the possibility of C axis.
I believe there are other options available instead of just replacing the spindle motor like a secondary servo for accurate positioning of the spindle? The 3 phase is a bugbear and would restrict saleability to the hobbyist but need to put that on one side for now.
Cheers
Mick
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You would likely get away with a smaller power motor then as a servo will be far superior to a normal 3 phase motor and VFD.
Regarding the C Drive, you will have to check with CS Labs to be sure but I don't think SwapAxis is supported so you would probably have to have two separate profiles, one for normal spindle and the other for C Axis.
You may manage to use relays to swap between the analogue outputs for spindle/C Axis but how well that would work I am not sure as you may get problems with following errors as the CSMIO would see the encoder moving on the axis (spindle or C Axis) when one or other is moving and be trying to keep the other stationary, recipe for disaster I fear.
You could probably have a second encoder for the C and somehow mechanically switch that in/out but again I don't think it would be a simple thing to do.
-
Hi Hood,
Why did you buy the software? it is available as a free download or at least it was.
I certainly looked and looked and then looked again....to no avail. This was at the time that you were on sabbatical.
The software is free if you buy new but given that I bought second hand.......I don't like spending hard earned money more than anybody
else but this purchase allowed me to make the best of another purchase, namely the second hand servo and drive, so I purchased and don't
feel too bad about it!
You can rest assured when I'm in the market for more servos Allen Bradley will figure very highly that I might reuse the software.
Craig
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Hi Mick,
Schneider have a design and production division in Christchurch, my home city as it were. I met a few of their engineers recently at an industry training
event. All nice guys and as clever as hell. They are very adept at designing and installing automated systems for food production locally and around the
world. When I spoke to them about servos they told me that even they had to pay quite steeply to satisfy their projects. I came to the conclusion, which
they generally agreed, that Schneider control the inflow of technology into New Zealand in a manner to keep the price and therefore margin high.
New Zealand has by and large no import duties or sales taxes excepting GST, rather like your VAT, and consequently we can buy stuff pretty reasonably
from any international manufacturer. That's not the case with Schneider. They are not alone.....Omron (representing Yaskawa) and NHP (representing
Rockwell Automation/Allen Bradley) have the same ethos.
They can get away with this because the lack of competition allows them to.
Craig
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Hi Hood,
Why did you buy the software? it is available as a free download or at least it was.
I certainly looked and looked and then looked again....to no avail. This was at the time that you were on sabbatical.
The software is free if you buy new but given that I bought second hand.......I don't like spending hard earned money more than anybody
else but this purchase allowed me to make the best of another purchase, namely the second hand servo and drive, so I purchased and don't
feel too bad about it!
You can rest assured when I'm in the market for more servos Allen Bradley will figure very highly that I might reuse the software.
Craig
This is the download link I just got from a Google search, you have to register with Rockwell to get it but registration is free and painless. Seems they are only doing the latest two revisions now, they used to list all revisions of it.
https://compatibility.rockwellautomation.com/Pages/MultiProductFindDownloads.aspx?crumb=112&refSoft=1&toggleState=&versions=51858,50195
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Just as an aside, when I got the Lexium drives I did a search for the Power Suite software for their drives and one link was to R S Components. It was, if I recall, around about the £2-300 mark which wasn't too bad as it woould have been split 50/50 with a pal as he got half of the motors/drives I bought. I then looked on Schneiders site and lo and behold there was a free download :D
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Hi Mick,
your musing about a 5kW single phase to three phase converter:
I have attached I pic of the specs for a Allen Bradley 2098-DSD-030 which is the largest single phase servo drive that I know of.
Note the continuous output current is 15A. Note that this is the peak amplitude, ie 15A peak or 10.A rms.
Note the continuous input current is 28A and the inrush and overload current is 50A.
This drive will handle about 2.2 kW or there about.
If you want to drive a 5.5kW servo then then input current would be something like 70A and the inrush/overload current 125A.
That's just plain physics......your domestic supply would never handle that.
Servos are very 'power dense' so the situation would be even worse for an asynchronous motor, by about 25%.
The last item I highlighted in the pic is the DC Link capacitors. The incoming AC supply is rectified and smoothed by the DC Link capacitors.
They supply the drive in between the charge cycles of the incoming rectified supply. If they are not large enough the DC Link voltage will
sag between the 50Hz peaks. If you wanted to improve the performance of a single to three phase converter this capacitance would have to
increase markedly.
A three phase drive receives rectified supply charge cycles three times more regularly and can have therefore a third the capacitance as its single
phase brother and achieve the same result.
The upshot is that you COULD run a 5.5kW motor from a single phase supply IF you are prepared to have the power supply company uprate your
connection AND you were prepared to build what amounts to a HUGE 320VDC power supply. All possible but not really practical.
Craig
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Hi Hood,
you have to register with Rockwell to get it but registration is free and painless
I tried that but without supplying a purchase number they wouldn't accept my registration.
To Mick,
sorry forgot to attach the pic that relates to my previous post.
Craig
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I use the DSD-030 drive with H and F 4075 motors, I am sure they are around the 3Kw size.
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Hi Hood,
I use the DSD-030 drive with H and F 4075 motors, I am sure they are around the 3Kw size
I'm sure you are right....the unit I was supplied is a DSD-020 and it does a pretty fair job of powering a 1.8kW servo. The truth is you
have to really push things to get it anywhere near its maximum and the amount of electrical energy circulating when you do is scary!
Craig
-
Specs of the motors on a DDM drive which is the older version of the DSD.
H series Low inertia I make a bit over 3Kw, the High Inertia F motors just under.
-
The F series would make a nice spindle motor on a smallish lathe.
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Hi Mick,
I thought to follow up on the discussion about LARGE single to three phase converters. Basically your power company would be
within theirs rights to say 'No, we will not permit you connect such a device to our network'.
The first pic is a representative circuit of an off-line input rectifier you might expect in a single phase VFD or servo drive.
The second pic show the currents and voltage when powered by a 230Vrms 50Hz supply. Note the output voltage (green trace), approx. 320Vpeak
but notice it sag between cycles. You would have to say that the DC Link capacitance is marginal for the output current.
Note the output current (red trace) is reasonably steady at about 12A but look at the supply input current (blue trace). It has peaks of about 180A!
This is a real problem....offline rectifiers draw current in high amplitude pulses with big gaps in between. The power companies hate that, they call it power factor
but in truth its more about current distortion. Any other customer hooked to the network is going to have their input supply degraded because of your device.
There are various means, both passive filters and active powerfactor correction circuitry that will solve this problem but they are expensive.
Given the plethora of electronic devices that have such simple input rectifiers and in ever increasing numbers, power companies are now having to insist on
powerfactor correction and prosecute you if you fail to comply. They have to try to protect their network for all our sakes.
Given the size of the inverter you would require for a 5kW motor I think you would come up in the power companies radar and they would ask some very pointed
questions and probably insist that you improve your installation. Industrial users are familiar with this problem and are required to spend somewhere between a quarter
and a half of their total cost of installation on the required powerfactor correction equipment.
Hood has pointed out that a 2098-DSD-030 can mange about 3kW, which is pretty damn fair. Given the exemplary torque characteristics of servos verses ansynchronous
motors I think you'd find this a very suitable replacement. Certainly it represents a practical limit to singe phase technology. DSD-030's are not nearly as common or as
cheap as the smaller 020's, but can be had for around $400US on EBay.
Craig
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One word of warning if thinking of going down the Allen Bradley DSD drive route for a spindle.
You have to be aware that these drives come in two main series, standard DSD-*** drives and High Voltage (ie 3 phase) they have a HV designation in the name so for example you get the low voltage (230V ) drive DSD-030 and the High voltage is DSD-HV030. Make sure you don't get the latter :)
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Hi,
I found a cheapie:
https://www.ebay.com/itm/Allen-Bradley-2098-DSD-030-Ser-B-Ultra-3000-Servo-Drive/123195136805?hash=item1caf009b25%3Ag%3AzmoAAOSwKX9apbWe&_sacat=0&_nkw=2098-dsd-030&_from=R40&rt=nc&_trksid=p2060353.m570.l1313.TR1.TRC0.A0.H0.X2098-dsd-030.TRS0 (https://www.ebay.com/itm/Allen-Bradley-2098-DSD-030-Ser-B-Ultra-3000-Servo-Drive/123195136805?hash=item1caf009b25%3Ag%3AzmoAAOSwKX9apbWe&_sacat=0&_nkw=2098-dsd-030&_from=R40&rt=nc&_trksid=p2060353.m570.l1313.TR1.TRC0.A0.H0.X2098-dsd-030.TRS0)
They range from as low as this up to about $2000 for new (old stock).
Another matter to be aware of with these drives (all the DSD-0X0's) is that they don't have a built in switch for a braking resistor.
There is a separate device that hooks to the DSD-0x0 terminals which when the DCLink voltage spikes due too deceleration switches in the braking resistor within it.
The devices come under great stress and blow up easily. They are not especially complicated, I'd make my own...electronics is my thing and I work in
the industry where I wouldn't even have to buy the components....they come over my bench as surplus all the time.
Craig
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The 030's and 075's do, the smaller ones, as you don't although in most cases it is not required.
BTW the DSD-075's are 3 phase 230v, the old DDM-075's could be used 230v single phase but were basically derated to 030's.
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Hi Hood,
you're right again, I didn't realize that!
I really got to get some of these suckers before they all disappear. I bought a house a while back and that has shot my CNC budget to hell!
Craig
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Hi,
found this....seems to suggest that the DSD-030 may struggle to power servos in excess of 2.2kW, recalling the DSD-030 has
a rated continuous output current of 15A.
Have noted also that the high power MPL-A4********* and MPL-A5********* are very thin on the ground on EBay whereas the smaller MPL-A3********* are dime a dozen.
Craig
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You better tell that to the Z axis on my lathe, it has been using an H4075 motor for 12 years, also the X axis uses an H or possibly and F 4050 which if I recall are over 2.5Kw.
MPL motors are different beasts from H and F series.
-
What you have to remember is the Ultra 3000's are old drives and they were designed for H and F series motors, MPL motors were not about at that time, the MPL motors are really meant for the newer 6000? drives.
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Hi Hood,
I know the feeling, I have an MPL-A430H which according to this table requires 12A whereas the 2098-DSD-020 I actually have driving it is capable
of only 10A. In use truly how often do you come even close to maxing your servo and drive?
I find that if I require maximum torque (output current) its usually at very much less than maximum speed. Given that the drive can be likened to
a buck regulator where the total out output current exceeds the DC Link current in the manner of a DC transformer that really I very seldom come
anywhere close to maxing the drive.
I can only conclude that the drives are generously specified and can accommodate a mild overload without blowing up. It comports well with my
perception of the quality and performance of the drive.
I some while back bought a refurbished 2.65kW servo, that is 14A at 180Vrms. It was manufactured in '95 and is fitted with an 8 pole resolver.
Trying to find a drive for it proved impossible, or least within my budget. I decided to make one, electronics being my thing and control engineering
being my training.
To get 14A rms per phase is going to require 28A rms input from the supply. I'll not get away with using such a device in the village I live, the power supply
degradation is likely to cause a complaint and thereafter the power company will track me down. I will have to therefore make a boost type PFC (powerfactor correction)
circuit. It will require a 10 second overload of 70A. You can be assured I've given the matter of input current distortion and output current, continuous and
overload, considerable thought in the process of designing my drive.
The 2098-DSD series will still being made in 2012 and thus were sold as compatible with the MPL series servos which started manufacture in the early 2000's.
Craig
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Yes the drives were still available and the firmware updated through time to encompass newer motors but originally they were designed for the motors available at the time, in fact they are basically just upgrades of the Ultra 200 drives which were upgrades of the ultra 100 drives which in turn were upgrades of DM drives. I have a few DM drives here although Osai branded rather than AB, then again the original makers were Electrocraft and I think AB eventually bought them out. That was probably why Giddings and Lewis stopped selling the Centurian drives as they were just rebranded ElectroCraft DDM and DSD drives. One of the 030 drives on my lathe is actually a G&L Centurion.
BTW the DSD drives are very adaptable beasts, I have a few motors running on them that were originally resolver motors, all I had to do was find a suitable encoder for them and then set up a custom motor profile.
My manual lathe uses such a beast, the motor is a 1326AB-A520E and the encoder is from an N series motor (same pole count) so it was ideal. The 1326 motors were meant for 1391 drives. The drive on the manual lathe however is an older DDM-075. They are similar drives but you can only have one custom motor in the database at a time, you have to overwrite it if you want a different one, the DSD drives allow as many custom motors as you like.
You do not even have to have commutation signals on the encoders as they will self sense on start but the drawback is when you power up the drives the motor will rotate slowly approx 1/4 turn to sense the commutation so it is not the ideal situation in a lot of setups. It would have been fine for my manual lathe but if I recall the DDM drives do not have self sense.
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Hi Hood,
kool, fascinating bit of history. It shouldn't surprise me that they were developed over a period of years. I mean it would be a tall
order for a manufacturer to come out with a new design that good right from the get go.
The history goes that I was looking for a servo for a mill spindle motor where I wanted torque at low speed for steel and stainless.
I got this 2.65kW unit I've talked about and thereafter decided to build a drive for it. Of course its taken ages and then I saw the Allen
Bradley 1.8kW servo and drive turn up on the NZ auction site and I bought it.
This is the first modern AC servo and drive I've ever had any experience with and simply it blew my mind as to how good and flexilble it is.
As a result of the experience I reallise now that I could use a DSD-030 drive to power my original purchase as you have recommended.
Really the pressure is off trying to complete my home built drive, I already have the Allen Bradley servo converted into a spindle and doing
sterling work for me.
I wish to persevere with making my own drive. I have had to learn to program a Texas Instruments TMS320F2069M micro controller
in C and C++ and complete with all the hardware peripherals it contains, the latest and greatest PFC devices, isolated gate drives and the
list goes on. I have always thought that the success of a hobby should be measured by what you have to learn in its pursuit. If that is indeed
the measure then making my own drive is very worthwhile.
Just exactly what a 2098-DSD-030 can or cannot manage I am at least sure it will power a servo that if Mick chooses to use as a lathe spindle he
will be very happy with. If he wants more grunt either get three phase power or go for some sort of extreme single phase solution, likely to cost
more than getting a three phase connection to his shop.
Craig
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If it would be big enough (power wise) then I think a DSD-030 with an F4075 motor would be the way to go for a lathe spindle as the high inertia is ideal.
It may be possible to use the Indexing features of the 030X ( or SE) drives to act as a C Axis as well, just depends on whether he just wants indexed positions or needs to have the axis rotating. If the former then you can set up 4 inputs to the Indexing drives to give you up to 64 predefined positions, it is what I do on the turret of my lathe.
Now for that to work it would have to be possible to disable the spindle in Mach3 and for the CSMIO to be happy with that, not sure if it can be done.
-
Hi Craig Hood
You pair are unreal. Wish I had 1% of your knowledge. Need to have a good read through all the posts and look at the motors and drives your quoting.
Cheers
Mick
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Hi Hood,
If the former then you can set up 4 inputs to the Indexing drives to give you up to 64 predefined positions, it is what I do on the turret of my lathe.
Now for that to work it would have to be possible to disable the spindle in Mach3 and for the CSMIO to be happy with that, not sure if it can be done.
There are some interesting questions bound up in that. Micks CSMIO is an analogue controller, to use the indexing feature would require that the CSMIO
stand out of the way and allow the drive to close the loop and move to the required index position. Quite frankly I don't know.
I have an ESS which is a step/direction controller and can be forced to stand aside while the drive completes some autonomous function.
Additionally I now use Mach4 which allows me much easier means of programming indexing operations verses free running spindle operations.
I would have to recommend just getting the spindle going in free running mode, which is still the most commonly used mode, would be adequate
to start with. THEN try puzzle out some way to introduce index ops.
Craig
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Yes, having the IP-A be happy about the spindle rotating via an external means would be the problem. You would have to disable the drive via Mach3 so that the IP-A knows it is disabled and does not try to correct for any subsequent movement.
I am not sure if that is possible or not as I have never tried, I know if I disable drives via Machs Reset then I can manually turn them and the IP-A tracks the position and updates Mach so that once enabled the position is still correct. Whether it would be possible to disable the spindle and enable the C Axis I am not sure.
Using the Indexing features of an DSD drive may not be the best way to do it anyway, it would just be one means.
If SwapAxis could be used (I don't think it can) then having the axis set as both spindle and C would be the ideal as you would then have a fully functioning C Axis or Spindle
On a friends lathe that I helped configure I set the Turret as a C Axis and it just gets commanded from Mach (via the m6start macro) and moves to the commanded position. Having it closed loop right back to Mach/IP-A is great as it means the encoder feedback is used to confirm the position has been reached. That however does not require SwapAxis or anything similar as it is not having to swap between two different functions, it is purely a turret set as an Axis.
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Justed looked at the Schneider BCH2MM152 1.5kw servo. Looking at the torque graphs it appears to only be marginally behind the 3kw Allen Bradley one. Obviously, this can't be right with half the power?
Craig
I already have the phase converter which I purchased a couple of years ago. It happily powers the 6kw spindle motor on the lathe. My preference would be not to use it and have everything single phase. If I come to sell the lathe in the future it will more than likely go to a hobbiest who wouldn't have 3 phase.
Cheers
Mick
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Hi Mick,
the Allen Bradley with the DSD-030 shows 8Nm at 3000rpm.
angular frequency= 3000 x 2 x PI / 60
= 314.1 rad/sec
power =frequency x torque
= 314.1 x 8
= 2513 W
=2.5kW
The BCH2MM152 shows 5Nm at 3000rpm
power = frequency x torque
=314.1 x 5
=1570 W
=1.5 kW
So firstly the power output of the Allen Bradley servo is 2.5kW not 3kW and secondly when is 5Nm ever 'nearly the same' as 8Nm?
You may note that the low speed torque of the Schneider servo is a little higher, in fact closer to 8Nm, than its ultimate torque, 5Nm, at rated speed,
but it does not mean its more powerful, I rather suspect that change occurs by virtue of the transformation effect of the drive rather than any
characteristic of the servo.
Craig
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Hi Craig
I was looking more so up to 2000rpm where they look very similar. Yes, there is a big difference at 3000rpm. Would these motors perform the same under 2000rpm?
Cheers
-
Hi,
It happily powers the 6kw spindle motor on the lathe. My preference would be not to use it and have everything single phase.
Don't think its going to happen, unless you are prepared to spend some serious money on a high current single phase connection
and suitable high current circuitry 5-6kW is beyond single phase. Hood is of the opinion that 3kW is achievable where my contention is
closer to 2.2kW. As to which if either of us is right does not change that we are in agreement that 5-6kW is beyond single phase.
Yes the two servos would perform almost indistinguishably below 2000 Hz where they are both capable of near identical torque.
The older Allen Bradley design likely has a greater moment of inertia and may therefore take a little longer to accelerate. Most likely
the rotating mass of the lathe is going to predominate in the moment of inertia calculation however.
Craig
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I can only go by what AB say as I am a bit thick when it comes to things of this nature.
-
Hi Hood,
who cares whether its 2.2kW or 3kW, Mick is never going to run 5-6kW from a single phase supply.
Craig
-
No, that is for sure but a 3Kw High Inertia AC servo may be adequate depending on the size of lathe.
-
Hi Both
There's been so many posts and loads of information. All getting confusing.
When you saying I can't run a 5-6kw motor from single phase. Are you talking about a servo motor? As I am running the original motor through my Digi Converter with no issues which is 6kw according to the plate.
Hood
The lathe is a Denford Senior 1990. It weighs about 2 ton. It has an X travel 0f 200mm and a Z of around 400mm.
Would the spindle servomotor need a built-in brake?
Cheers
-
That sounds like a big lathe if it is weighing in at 2 Tonne.
Can you shove a pic up of it as I am not really finding anything online that sounds similar.
What spindle nose does it have?
-
Hi Hood
Please see attached.
The chuck is 150mm. Maybe 1.5 ton certainly no lighter.
Reading back over the posts and reference my last post I presume you are both referring to a 5-6kw servo as opposed to what I have now.
If so it was never my intention to put a 5-6kw servo on the lathe. My preference would be to do away with the phase converter.
Cheers
Mick
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This available on ebay
https://mesg.ebay.co.uk/mesgweb/ViewMessageDetail/0/All/100769238578
With this servo drive
https://uk.rs-online.com/web/p/servo-drives-controls/1110816/?relevancy-data=636F3D3126696E3D4931384E53656172636847656E65726963266C753D656E266D6D3D6D61746368616C6C7061727469616C26706D3D5E2E2A2426706F3D31333326736E3D592673723D4175746F636F727265637465642673613D6C786D3238617534356D33782673743D43415443485F414C4C5F44454641554C542673633D592677633D4E4F4E45267573743D4C584D32385534354D3358267374613D4C584D32385534354D335826
Would mean keeping the single to three-phase inverter. I can buy this drive for £300. C axis costing approx £850
Would prefer to get used to programming the one type of drive. Rather than using Allen Bradley and Schneider.
Cheers
Mick
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Ok, well I would say it will be 1 tonne or under from the looks of it but pics can be deceptive. It kind of looks similar in bed design/size to a Hardinge HLV and I think they are about 750 -900Kg range.
Anyway that doesn't matter :D
Regarding the 5-6Kw motor, I am not sure what we are meaning any more :D 2.5-3 KW servo will be your max on single phase and I think you may get away with that. I have a 5kw on my manual lathe which is a Colchester Triumph which is physically a bigger machine than you have, it is too small in reality but that is because I am also using it to feed the gearing after the spindle as well, so it is using a lot of its power up for that. If I was simply using it to drive the spindle, which you will be doing, then it would be plenty.
I would say a F4075 Allen Bradley motor would do that fine but it is not a definite, just what I think.
The link you posted for the motor is dead so not sure what it is.
Regarding programming two different drives, I wouldn't worry about that as the AB drives are very easy to set up, the software is simplicity itself although the tuning is not as easy to do as with more modern drives, still fairly easy though.
I can however see why you want to go down the Schneider route, especially with you getting very good prices.
-
Sorry about the link.
My initial thoughts were to get rid of the Phase inverter to use single phase, but Going down the Schneider route leaves me no option but to use a 1.5kw spindle drive which is underpowered over 2000rpm than the F4075 that we have been debating. I totally agree that using the Allen Bradley f4075 and associated drive will work but then I will have to buy these used and wait for them to be available or if I buy new will cost £0000's
If I continue to use the single to three phase converter then I have loads of options including 3 phase which I can buy at sensible money. The link is for a 3 phase 3.5 kw motor with brake. I can buy the recommended drive new for £300. meaning the spindle motor/ C axis would cost £850.
For a novice it would be easier in my mind to stick with the same motors and drives on all axes.
https://www.ebay.co.uk/itm/323378737601?ul_noapp=true
Cheers
Mick
-
Is 2000rpm enough for you? If so then probably best to go the new route.
-
Hi,
If I continue to use the single to three phase converter then I have loads of options including 3 phase
You have a single phase to three phase converter of 6kW output?
Can you provide some details, maybe a shot of the nameplate?
Craig
-
Oh forgot to answer your earlier question regarding the brake. No it is not really needed on a spindle.
Servo motor brakes do not hold the motor stationary, there is always some movement, not a huge amount but there is some, so the brake is no use for locking a spindle.
Also a brake is not used (normally) to stop the motor, it is used primarily for holding, think a Z axis on a mill or the X axis on a slant bed lathe. When the drive is disabled the brake will come on so that the axis does not drop under gravity.
-
Hood
Is 2000rpm enough for you? If so then probably best to go the new route
What do you mean? New route as far as single phase or keeping the phase converter?
Craig
Yes, I do have a digi phase converter from a company called SMP in Stourport. Will send pic tomorrow. would you like a video of the 6kw motor at full Rpm?
Cheers
Mick
-
By New route I was meaning new servo drive and motor that you linked to rather than second hand Allen Bradley.
-
Cheers Hood
This is also available 3kw without the brake instead of 3.5kw. Half that price.
https://www.ebay.co.uk/itm/Schneider-Electric-3kW-BCH2-Servo-Motor-220V-19-1nm-3000-rpm-1005L-1110831/223079117579?hash=item33f08d330b:g:N9EAAOSwe6FaJrx7
Cheers
-
Only 1500rpm though.
-
Craig
Please images of my phase converter temporarily attached to my lathe.
Here is a link to a 15hp one on ebay. Very popular over here.
https://www.ebay.co.uk/itm/Digi-phase-Converter-1-3-Phase/183353569642?hash=item2ab0b9716a:g:bYAAAOSwhilbYKsy
Cheers
Mick
-
Strange it says that in the Manual but the torque graph shows 19nm up to around 2600rpm then drops to 9nm at 3000rpm???
Cheers
-
Strange indeed.
-
The BCH2MR3023CA6C shows 14NM straight through to 3000rpm. Would this be a better option?
Cheers
-
Hi,
Strange it says that in the Manual but the torque graph shows 19nm up to around 2600rpm then drops to 9nm at 3000rpm
Its called 'field weakening', a clever technique for extending the rev range of a motor which would otherwise top
out a a lower speed due to lack of voltage. This is a pretty radical reduction though.
Craig
-
Hi,
the first motor:
power =2600 X 2 X PI / 60 X 19
=5172 W
the second:
power = 3000 X 2 X PI / 60 X 14
=4397 W
So despite the first motor dying at speed, in the field weakened operating condition, it is still the more powerful motor.
Hey, all these high power motors are wonderful things but you have to squeeze the electricity to run them
through your domestic supply. Not withstanding what looks to be a really impressive single to three phase converter
you will still have to supply it something like 60A to produce 5kW output. Will your domestic supply and cabling
accommodate such high currents?
Craig
-
Hi Craig
Thanks for the info. We have a 100amp single phase supply. If I remember right I had to put a 50 or 60amp B rated breaker in. For the initial surge.
I believe the motor in the converter is bigger than 5.5kw.
Cheers
-
I need to speak to SMP as there website is no longer showing these converters. Don't want to spend the money on the 3 phase spindle then have a problem with the converter and not be able to get it repaired. ???
Cheers
-
Hi Mick,
kool, it sounds then that you have taken some precautions against overloading your supply.
Just a few thumbnail calculations:
current (assuming unity power factor) =5000 (W)/ 230 (V)
=21.7A rms
21A doesn't sound too bad does it? But remember this embodys the assumption that unity power factor, ie perfect power factor applies.
We all know that there is never a perfect power factor. I would be prepared to guess that the converter you have is good, even very good, it
would certainly account for their popularity. Lets assume that your converter has a power factor of 0.95, most industrial electricians would regard
that as very good indeed.
current (assuming 0.95 power factor) =21.7 / 0.95
=22.9A
Still pretty fair, only 23% of the current available from your 100A domestic supply.
The real trouble now comes when three phases generated by your converter are applied to your servo drive. You recall the circuit diagram that I posted
earlier, the three phase version is very similar and suffers the identical power factor problem.
I repair welders for a living, inverter welders particularly. Day after day I see for instance a single phase stick welder producing 100A at 20V into
our load bank and yet 20A indicated current coming from the single phase supply. We'll do the energy balance to determine the effective power factor of this
situation:
input power (indicated)= 230 (V) X 20 (A)
=4600 W
output power( actual)= 20 (V) X 100 (A)
=2000 W
Power Factor (effective)= 2000 / 4600
=0.438
Just about all single and three phase off-line rectifiers suffer this power factor degradation. There are circuits to correct it, I suspect your converter uses them
but your proposed servo drives do not.
Thus lets now calculate the current required by your servo drive referred back to the single phase supply assuming this power factor:
current (single phase equiv)= 5000 (W) / 230 (V) / 0.438 (power factor effective) / 0.95 (power factor converter)
=52.24A rms
Lets put that number into perspective. Firstly its one half of the rated supply of your domestic network connection. Secondly it near the circuit breaker
rating and this is just rated current, not any overload or inrush current.
You can see now that the power factor, which is far from an easy measurement, affects so dramatically the required input current. I've seen power factors
as low as 0.3 but 0.4 to 0.5 are the norm for reasonably made off-line rectifiers of simple type. You can also see my concern that you might cause your electrical
installation harm or risk fire or injury unless you understand the demands of your servo drive.
Craig
-
Hi Craig
Thank for taking the time on this. This is definitely something which needs checking prior to going for the Servo Spindle. We run an 8kw heat pump which gets used a lot through the winter. Excuse me for being thick but can you please explain a little more. I apologise if you have already covered this.
the first motor:
power =2600 X 2 X PI / 60 X 19
=5172 W
the second:
power = 3000 X 2 X PI / 60 X 14
=4397 W
I don't understand why we are getting 4397w when the motor is rated at 3000w
The motor on the lathe at the moment is 6kw at 65HZ at 1950 rpm at 15A according to the plate. Can we run this motor at full speed and use a clamp meter to check the amp draw. Taking away assumptions of the power factors. Then work back from this with the servo motor ratings?
Cheers
Mick
-
Hi Mick,
I don't understand why we are getting 4397w when the motor is rated at 3000w
Nor do I but you provided the torque and speed figures. The shaft output is just that, it has no bearing on the electrical
means by which it was generated and the calculation is exactly as Isaac Newton proposed.
My guess is that the torque figure supplied was somewhat higher than its 'rated torque' The motor does not just stop when its gets
to its rated torque, if the drive produces yet more current the motor will produce yet more torque and therefore power to the load. Over a period
of time you might expect it to overheat. The 'rated' output is more about a thermal condition rather than an absolute limit.
There are two figures of merit that apply to servos which can be relied on to produce accurate numbers. The first, called the torque constant or Ka
is in so many 'Nm per Amp' Thus if a motor is supplied 10A and its Ka is 0.95 Nm/a then its torque at that operating condition is 9.5Nm.
The second is called the back EMF constant or Kv in so many 'Volts per 1000 rpm' or some other equivalent units. Thus a motor spinning at 2000 rpm
with a Kv of 100 V/1000rpm will have a back emf of 200V. If our supply is 230V, the motor cannot run much faster as the back emf is close to defeating
the applied voltage.
The two numbers relate very much to the design and construction of the motor. In general we want Ka to be high, that is a motor than can produce
a lot of torque from a small current. For instance you might decide to have a high number of turns in the stator so that it produces a strong magnetic
flux for a given current and choose high strength rare earth permanent magnets for the armature.
Both of these however increase Kv also, and as we have seen its the back emf that determines the motors top speed for a given input voltage.
You came across an example yesterday where a servo produced high torque up to 2600rmp and then seemed to die. The Kv figure is such that the servos top
speed with 230V input is 2600 rpm. To get it to go faster you have to artificially manipulate its Kv, which can be done, within limits, with field oriented control
with a technique called field weakening.
Craig
-
Hi Craig
Thank you for the detailed explanation but I am more confused now. Can we check the amp draw via a clamp amp meter using my existing motor to confirm the draw and not be guessing power factors and everything else that's drawing power?
Cheers
Mick
-
Hi,
thats not going to be easy...how do you intend the load your existing spindle to rated output?
I would be less concerned about your existing spindle, its likely to have a power factor of 0.8, not
great but not too bad either. Likewise your single to three phase converter is likely to be very good.
The trouble comes when you fit a servo drive, they have a simple rectifier input and could draw much
more current than you think. Without one to test and some means of loading it to rated output
you won't know.
Given that the current is drawn in pulses even supposed 'real rms reading' meters are not really that good.
Thus you would need some good gear to make effective measurements. By that stage you already have
your drive and servo....its a bit late to decide you don't want it after all.
Clearly you have made some allowance for increased current draw at the time you fitted your converter, I would
think you can afford to box on. If it proves that the current draw is excessive then you will just have to back
off your demand....which you can set by taking a lighter cut...OR...setting a realistic current limit by programming
your drive.
Your 100A supply and 50-60A breaker should allow you to proceed safely. As I have said before its actually really hard
to load up motor that much, you may find that all of these precautions are uneccessary.
Craig
-
Hi Craig
Thank you.
The other thing I would need to buy is 3 phase step down transformer. The 3 phase drives are 220v 3 phase and the converter puts out 430v.
Cheers
Mick
-
Hi,
these three phase 200V drives are for the Yanks. There is no need for you to follow suit.
Your converter outputs three 230V-to-neutral phases or 400V line-to line. You should be getting a drive and a servo to accommodate that.
For instance the Allen Bradley numbering goes:
MPL-A430H where the A stands for 230V and
MPL-B430H where the B stands for 400V operation. Note that it is common to state the AC line voltage for which the servo/drive is matched
when in actual fact they will operate at the DC Link voltage and the DC Link voltage derived from a 400VAC supply is 560VDC.
Craig
-
Hi,
you have been looking at the Lexium 28 series which are 220V single or 220V three phase units.
You need to look at the Lexium 32 series:
https://www.schneider-electric.com/en/product/LXM32SD30N4/motion-servo-drive---lexium-32---three-phase-supply-voltage-208-480v---3-kw/?range=2302-lexium-32-%26-motors&node=166536672-servo-drives (https://www.schneider-electric.com/en/product/LXM32SD30N4/motion-servo-drive---lexium-32---three-phase-supply-voltage-208-480v---3-kw/?range=2302-lexium-32-%26-motors&node=166536672-servo-drives)
There you will find 380-480V versions.
Craig
-
Hi Craig
Cheers for the info. did think it was a bit strange for everyone to have to use step down transformers. Will check them out.
Mick
-
Hi
Does anyone have a spindle torque calculator to hand? Where I can input stock diameter, material, feed rates etc. Going round in circles on the net.
Cheers
-
Hi Mick,
HSM Advisor, liked it so much i bought it.
Craig
-
Cheers Craig will have a look.
Hi All
Is this motor worth looking at?
https://www.schneider-electric.com/en/product/BMH1401P37A1A/servo-motor-bmh---10.3-nm---4000-rpm---keyed-shaft---without-brake---ip65-ip67/
On single-phase up to 1500 rpm has 9.9nm then drops to 7 as opposed to the DDM's 7.9nm at 2000rpm. Over that, it drops significantly.
It also has a lot higher peak torque of around 32nm.
If it proved to struggle around 2000rpm or I needed more rpm, I could change the drive to a three-phase 440v giving higher torque values than the DDM that I think we have suggested will be sufficient.
Cheers
Mick
-
Hi,
what are you trying to achieve? If I understand correctly you have a working three phase asynchronous spindle motor of 5kW.
Is that correct?
What are you hoping to achieve by replacing it? You mentioned the desirability of having it operate from a single phase supply.
Hood and I chimed in and we agree that the potential for a single phase servo is in the region of 2.2 to 3kW. Even that will put significant
demands on your supply and still be well short of power compared to the original spindle motor. I recall that you thought that operation
from a single phase supply would be a favourable selling point, and I imagine it is....but are you planning on selling it?
You will have noted that the higher the input voltage to the drive the faster the servo can run before the torque diminishes. That would lean you to
a three phase input servo drive, but that really is contrary to the idea of running it from a single phase supply.
I understand that you are going to buy a couple of 750W servos and drives for the axis drives. I commend that idea to you, it will give your lathe a new
lease of life. May I suggest that at least for the time being that you retain the existing three phase spindle motor while you get your axis drives and
controller on line. I suspect that the experience you gain with programming and handling the smaller servos will give you good insight to the potential
performance of a larger servo for a spindle and also maybe an appreciation of it problems also.
If you are dead set on having a servo as a spindle motor, and as you know I have done just exactly that for my mill and delighted with it, then you will want
the most capable motor you can afford and/or your electrical installation handle. That would tend to favour 400V drives, the servo being run with such a drive
goes that much faster and retains its torque that much longer. I would think that the exemplary torque characteristics of a servo would mean that a 4kW servo
would hold its own handily with a 5kW induction motor, if not absolute power, but the handling characteristics would be favourable. Below about 4kW
and I suspect that you would start to notice the lack of power.
A 400V servo and drive capable of 4kW is not going to be cheap, even at the discount your wife can secure. Also a large servo like that is going to place
real demands on your supply and you would have to allow some budget to improve that situation as best you can, I'd think line reactors as a minimum.
Craig
-
Hi Craig
I am trying to achieve two things. One was to have everything running off single phase and two was to turn the spindle axis into a controllable C axis. The lathe can potentially do a lot more with a C axis.
No, I am not thinking of selling it but if and when I do it would be more saleable.
I think its clear that using single phase is not going to be an option for the spindle and after further thoughts and following all your comments, it makes sense to use a larger motor and not restrict what the machine is capable of.
I have ordered the 750w motors and drives for the X and Z axis, absolute bargain at £718.00 with all the cables. Delivery is 16th August.
Thanks for your input on this again.
Cheers
Mick
-
Hi Mick,
had a few days to review the discussion to this point.
It seems to me that the critical choice to make if you are to re-power your spindle with a servo is not the servo so much as the drive.
As you have seen their are a number of servos which can be driven by a particular drive but largely it is the drive that determines how well
any of those servos perform.
As a result of that I conclude to have a good as possible solution will require a three phase input drive and any servo driven by such a drive (400V)
will achieve its best or very near to it.
The drive input characteristics are particularly important as your phase converter must supply its input current.
I have attached the spec page and have highlighted the salient figures of the LX32 D30N4 being a three phase input drive with nominal input of 400V
and nominal output of 3kW.
Note the data for the drive in ABSENCE of a line reactor:
nom input 8.2A per phase
nom output 3kW
indicated input power= 8.2 x 230 x 3
=5658W
The effective power factor is
power factor =3000 / 5658
=0.53
Note this is somewhat better than I had predicted in an earlier post,but not that much better.
Given that your phase converter is limited to 5kW output your drive could supply no more than 2.6kW to a servo before it starts to overload the converter by virtue
of its poor power factor.
Note the data FOR THE EXACT SAME DRIVE but WITH LINE REACTORS:
nom input current=11.1 A per phase
nom output power=5.6kW
indicated input power=11.1 x 230 x 3
=7659 W
effective power factor= 5600 / 7695
=0.73
Notice how the power factor has improved markedly with the addition of 1mH line reactors.
Your phase converter could now deliver 3.65kW to your drive without overload, a substantial gain over the 2.6 kW without reactors.
Simply put, the poor power factor of servo drive limits the shaft power developed by the servo, not because of any inefficiency of the servo but the poor
power factor of the drive stresses the supply. Even simple line reactors improve the situation markedly. An even more sophisticated input filter could achieve
an even better result although there will come a point of diminishing returns.
This is an area you need to explore if you wish to re-power your lathe spindle with a servo. With a good combination of line reactors and filter elements you might
achieve power outputs to match the existing induction motor WITHOUT ANY EXTRA SUPPLY STRESS. I feel sure that Schneider technical sales reps would help and
I imagine would also be able to supply the required components. Downside is that the cost could be a significant fraction of the servo and drive.
Craig
-
Thanks Craig
That's a huge jump by just fitting a Line Reactor. Never heard of one but just been reading up on improving power factor. Interesting stuff, wished I fully understood it.
By the way, the phase converter is 5.5kw. Max single motor size 7.5hp.
There is an Amp meter built into the line side of the converter. Not sure if you noticed.
Mick
-
Hi Mick,
There is an Amp meter built into the line side of the converter. Not sure if you noticed.
No, I didn't see that.
In the area I live there has been an explosion in the number of farmers irragating land with 100-300kW
down-hole pumps powered by VFD's. These are all rurally sited and the degradation of the power supply is so accute
that rural residents are having TV's and computers etc blow up. The power companies are insisting that farmers
fit power factor/distortion mitigation equipment, and its expensive....and they hate it.
I suppose, they seem happy enough to pollute the environment, so polluting the power supply doesn't seem that big a deal.
The upshot is that whether you understand or not, by virtue of being constrained by your converter you will have
to come familiar with and use the techniques and equipment available.
Craig
-
Hi All
Need to get a EMI filter for the drives I've ordered.
The motors are BCH2LF073
The spec say 4amp continuous and 13amp rms.
What ampage does the filter need to be?
Can I use one filter for the two drives?
Cheers Again
Mick
-
Hi,
what does the manual say?
What does the Schneider rep recommend, you can bet your bottom dollar they will have all that stuff and would love to sell
it to you.
My general understanding is that because of PWM of the output you DO NOT USE CAPACITIVE FILTERS (on the output) WITHOUT SPECIFIC ADVICE to do so
from the manufacturer. The capacitive current will give the MOSFETs/IGBTs a real toweling at switch on/switch off. If there is capacitance recommended on the output
I would expect a few nF at most.
On the input side you want line reactors. You can use T section filters also but still you don't want to show excess capacitance to the drive.
Craig
-
Drives and Servos arrived. Bit concerned they are half the size if the old Dc Motors. Modern technology I hope. Lol
-
Hi,
remember one of those two figures of merit, one in particular Ka, the torque constant. Your 200V servos are likely to have a Ka
of about 1 Nm/A whereas your DC servos might, on a good day, have a Ka of 0.5 Nm/A.
So for the same current the new AC servo will produce twice the torque.
Craig
-
Cheers Craig.
I don't doubt the motors at all after all the discussions ;D ;D.
Just trying to get my head around the encoder wiring to the controller at the moment. It seems I only have T+ T- GND and 5Vdc.
Loads of reading to do.
-
Hi,
that sounds like a serial encoder output. You will not be able to hook that to your CSMIO.
You will instead hook it directly to the drive, it can and will read the encoder signal and as Hood has suggested the drive will synthesize
A+,A-,B+,B-, Z+ and Z- that you can hook to the CSMIO.
Craig
-
Hi Craig
The encoder does wire straight to the drive. The output to the controller only has four wires. T+ T- Gnd 5vdc. I may be mis understanding the wiring info. Lots of info.
Mick
-
Hi
Like I said lots of reading to do. Lol
Ignore the last post I think the output to the controller is on CN1 50 pin plug.
It appears to be on CN1 plug pins 21,22,23,24,25,50 you have A+ A- B+ B- Z+ Z-
Not sure where the GND and 5VDC are coming from though at the moment.
Cheers
-
Am I right in thinking it doesn't need the GND and 5VDC from the controller??
Cheers
-
Hi,
I suspect the pairs of outputs, A+ and A- for example, are the collector and emitter of a phototransitor respectively.
Thus the switch current will have to be provided by the CSMIO.
Craig
-
Hi Craig
Thanks. Will have more time to read up over the weekend.
Mick
-
I suspect the pairs of outputs, A+ and A- for example, are the collector and emitter of a phototransitor
I would hope that they would be differential 5V signals, e.g. from a line driver or similar. That would allow a direct connection to the CSMIO. This is the case with my Kinco drives.
If they are photo transistors, some external logic, if only pullup resistors, will be required, which rather messes up the wiring.
Allan
-
Hi Allen
Not sure what they are yet. Only got them yesterday and have had chance for a full read. Would you mind taking a look at the manual.
Cheers
Mick
-
Mick
Sorry, with page after page devoted to the spindle drive, I got a bit muddled as to what you decided to use for the axis. Could you re-post the link for the actual axis drive you have purchased?
Allan
-
Hi Allan
Thanks for coming back in. The motor and drive links are below. I cant attached the manual the file is too large so I have sent a link to it.
https://www.schneider-electric.co.uk/en/product/LXM28AU07M3X/motion-servo-drive---lexium-28---single-and-three-phase-200...230-v---750-w/
https://www.schneider-electric.com/en/product/BCH2LF0733CA5C/servo-motor-bch---80mm---750w---w-oil-seal---w-key---leads-con/
https://download.schneider-electric.com/files?p_enDocType=User+guide&p_File_Name=LXM28A_Manual_V2.1_EN.pdf&p_Doc_Ref=0198441114054-EN&_ga=2.266361352.789260454.1534532339-227965827.1533213090
Cheers
Mick
-
Hi,
looks like Allan has it right the synthesized encoder outputs are line driver, see pg 156 of:
http://download.schneider-electric.com/files?p_enDocType=User guide&p_File_Name=EIO0000002305.02.pdf&p_Doc_Ref=EIO0000002305&_ga=2.101965250.2111833376.1534533331-1177742663.1534533331 (http://download.schneider-electric.com/files?p_enDocType=User guide&p_File_Name=EIO0000002305.02.pdf&p_Doc_Ref=EIO0000002305&_ga=2.101965250.2111833376.1534533331-1177742663.1534533331)
I see that the driver can swing a few volts only. Is that enough for the CSMIO?
Craig
-
Mick
Thanks.
The 6 ESM outputs are RS422 line drivers, which is the desired differential form at at nominally 5V levels. You can and should connect these directly to the CSMIO encoder inputs of the same name. You should use twisted pairs, preferably screened. 24awg (1/0.2mm2)Screened Cat5 cable is convenient for this.
I cannot see that any +5V connection from the CSMIO is needed, though I've just had a quick peep so far.
Craig
You just beat me to it. Yes, RS422 is ideal for the CSMIO.
Allan
-
Hi Allan,
kool. I would have thought that the CSMIO and the servo drive would have to share the same earth potential.
I know the output of the drive is differential but to allow an undefined zero point would require the CSMIO be able to tolerate
a common mode voltage outside its own power supply rails and require that it have sufficient common mode rejection ratio that
the common mode voltage does not swamp the signal.
Craig
-
Hi Allan
Great news, thanks for taking the time again and proving a rapid clear answer. I will be using the pre-wired sub d 50 CN1 cables. I did order them but haven't arrived yet >:(. Will get the motors and drives fitted over the weekend and delve into the operating manual.
Cheers
Mick
-
Craig/Mick
I'd only spent 5 minutes or so with the manual before writing my last post. Mick had previously asked about the 5V and that seemed pretty obvious as there was no 5V input line on the drive, or if there was then I missed it.
I agree totally that one would not want different 0V systems for the CSMIO and the drive. Excessive common mode levels could cause erratic behaviour or even physical damage in the worst case. CSMIO has 0V outputs on the encoder connector which should of course be tied to the ground reference for the ESM drivers. I do this with my Kincos. But with Mick's drive I wasn't at all sure where this connction would best me made and need more time to see if the manual clears this up anywhere. It was not obvious to me at first sight. There is also the question of what signals are within the made up ESM cable to the CSMIO and whether these include 0V.
Allan
-
Allan Craig
Thanks for expanding on this. Am I right in thinking we are talking about GND Pins on the CSMIO not being used, the potential issue. Eg pins 17,21,25 on the encoder inputs?
Would this be something Cs Labs could help with or maybe Schneider Technical? The issue with talking to Schneider technical would be my lack of knowledge in circuits :-[.
Cheers
Mick
-
Mick
Yes, the GND pins you mention above are what we are talking about. Essentially, we are saying that this ground potential must also be the one used by the drive as a reference for its ESM outputs.
I haven't had time to give the manual much attention as yet but it looks as if pin 49 on CN1 is the only common ground for all of the drive's digital signals. It is also the common for the 24V power supply to the drive. As we don't want to contaminate any of the analogue grounds with digital noise, pin 49 appears to be the only option.
Assuming you are using the same 24V supply for the drives and for CSMIO, their commons are bound to be connected, and that, in essense, should be enough. If you have separate 24V supplies, make sure that their 0V commons are connected together. If the cable you are using has a ground wire, by all means connect it to one of the CSMIO ground pins. If it only contains the 6 ESM signals, just make sure the power supply ground is common for the CSMIO and the drives as above. It is unlikely that you will experience noise issues on these differential signals, and unless you do, I wouldn’t worry about it any further.
Allan
P.S. I somewhat sloppily tend to use the workds ground and common interchangeably. To be clear, in both cases I am referring to the circuit 0V line, and not to the protective earth (though these will likely be bonded somewhere).
-
Hi Craig
Ok I think that makes sense. I will be using the same 24v power supply so this shouldn't be an issue. I really need to do some more research on the difference between GND, COMMON, 0V.
Cheers
Mick
-
Hi,
I' guessing hat if you have the setup software installed on a PC you can not only program the drive but you can run it, that is to say
have it move to indexed positions or accelerate to a given speed without the need for the CSMIO. Certainly the Allen Bradley software allows
such use. You can use the built in software scope to tune the servo. In your case you really only need to tune the velocity loop and the chances
are that the default tuning is going to be that close to perfect as is, you could make it worse but unlikely you could improve it.
Either way it is a fun way to use your servos and get familiar with them without having an external controller.
Craig
-
Hi Craig
Yes, I do have the software installed but unfortunately, I didn't get the RJ 45 to USB converter cable. Reading up you can do most of the stuff direct from the Drives control panel. I've been looking at the scaling information which is confusing me slightly at the moment. :(
Cheers
Mick
-
Hi,
do yourself a favour, get the cable and use the software. Programming through the panel is a joke.
Craig
-
do yourself a favour ...
Absolutely agree.
Allan
-
Hi
Yes will do but everything is a 6 working day lead time with this stuff.
Will have a dabble in the mean time.
There are loads of rj45 to usb converters freely available on the net. Would these be a standard cable? Or would I need the genuine one?&
Cheers
-
Hi,
hey.....six days....you could in the meantime buy your missus flowers, a night out on the town, cook her a romantic dinner....and have just
enough brownie points to get that spindle servo! LOL
Craig
-
Lol
Your a funny guy.
Cheers
-
These work for the Lexiums not sure about the drives you have though.
https://www.ebay.co.uk/itm/KMTronic-USB-RS485-FTDI-Interface-Converter-BOX-/281257472746?hash=item417c4072ea
I also got an adapter set from RS which did various drives but it was for serial connection to the computer so I also needed a serial to USB adapter, which I already had anyway.
I will see if I can find the RS link but I think it is more expensive.
-
Hi Hood
Cheers for the link. I've ordered the one from Schneider now. Along with the CN1's that didn't arrive. >:(
Mick
Craig
I took your advice on the flowers and she's pricing the spindle drive and motor in the morning. Lmao
-
Hi All
Any idea where to buy the D SUB 50 connectors? Ordered genuine ones from Schneider with pre-attached cables who are now saying they are made to order with no guaranteed lead time. They are not the standard DSUB 50 connectors. They are about half the size. I can't find any more info in the manual except DSUB 50 >:(
Cheers
Mick
-
Hi,
I suspect they are high density sub D . I got mine from Element14.
Can you post a close up pic? Also the overall length, I'm guessing it has the same shell size as a DB25 parallel printer cable
but with double the number of pins.
Craig
-
Hi Craig
I'll try searching that.
The screws to hold it in are 47mm apart. It only has 2 rows of pins unlike the standard SUBD 50 which has three. Searching RS components who sell everything but still struggling.
These will be a pain in the A*** to solder.
Cheers
-
Hi
Picture attached.
Two rows of pins.
Cheers
-
Hi,
that pic is TOO big, try cropping it and resizing so it turns out about 500kB.
I suspect it is micro D. What I can't decide is whether its meant to have four rows of contacts of which only the outer two are used.
http://nz.element14.com/3m/10150-3000pe/plug-mdr-solder-50way/dp/9292667 (http://nz.element14.com/3m/10150-3000pe/plug-mdr-solder-50way/dp/9292667)
Craig
-
Hi,
that last link was for the plug, you probably need the receptacle:
http://nz.element14.com/3m/10250-6212pl/receptacle-mdr-straight-50way/dp/9292861# (http://nz.element14.com/3m/10250-6212pl/receptacle-mdr-straight-50way/dp/9292861#)
Craig
-
Hi Craig
The picture I sent was the drive. The connection is receptacle on the drive. Just looking at your link.
Cheers
-
Hi,
I think SCSI cables are 50 way micro subD.
Craig
-
Hi,
yeah, SCSI II cables:
https://nz.rs-online.com/web/p/scsi-cable-assemblies/1823933/ (https://nz.rs-online.com/web/p/scsi-cable-assemblies/1823933/)
Craig
-
Hi Craig
Yes, you are right. Looks like an SCSI connector. I don't think I cant use that pre-wired connector. The data sheet shows different twisted pairs combinations to what comes out the servo drive?
Cheers
-
Hi,
to be honest at the price of the cable I was looking at I'd have a go even if the cable pairs
were not quite correct. I'd be gambling that the mismatch of the twisted pairs doesn't matter.
Otherwise you are going to have to solder it all together, not easy, I've done it.
All these delays....are going to cost you a fortune in flowers etc to keep your missus sweet!
Craig
-
;D Lol
I was under the impression that not using twisted pairs was a big no-no on the encoder channels?
Cheers
-
Hi,
no, it may not work, but it wont do any harm.
Given that the 'encoder signals' are actually synthesized in the drive I assume you have considerable
flexibility as to what resolution they are and may therefore choose a resolution such that the max
frequency is 100kHz or so. Remember that with quadrature encoders that means a 400kHz count rate.
100 kHz signals could be transmitted single ended ie not twisted pair over short distances no problem.
Craig
-
Hi
Cool. Probably worth a go then. I'll get a couple ordered.
Cheers
-
Hi,
the one that I was looking at had two indentical plugs, you might be able to get one and cut it in half.
Craig
-
Hi
That one goes from SCSi 1 to SCSi2. Both male though. There only £12.00 so happy to buy two. Doesn't give any pitch dimensions though. I think there a few different ones. Mine is 1.27mm pitch.
Ill give Rs a ring in the morning see if they have any more info.
Cheers
-
Craig
I'm not at all clear what these connectors are. The drive manual doesn't appear to specify this, which is a pretty poor show. Are we talking about the 3M MDR (micro Centronics style) which are a pig to solder, or arethey something else~? The term micro D seems to cover various proprietarty designs.
Would it be worth asking Sneider to confirm?
Allan
-
Yes absolutely just says SUB D 50 way. I was going to give them a ring in the morning.
Cheers for your time again.
Mick
-
Hi,
on the Element14 links I posted to both the plug and receptical there is a link to the
data pages which give the dimensions.
Both of the ones that I looked at were 3M series 101 for the plug and series 102 for the receptical.
If I understand the D shell is standard, that is to say that the length and width of the shell are in about
one of six standard sizes. Thereafter there are a number of styles for the arrangement of contacts,
including 'standard' which is two row 0.1 pitch, high density which is three row, Centronics, a copy of
a proprietary design and micro.
While Mick gave the spacing for the retaining screws the defining dimension is the D shell. There is a variance
of the inside and outside D shell but it imediately defines many of the dimensions.
Craig
-
Late to the party but it looks like the 3M MDR connectors that the Samsung drives use. 3M 10150 is a 50 way connector.
https://uk.farnell.com/3m/10150-3000pe/plug-mdr-solder-50way/dp/9292667
-
Pics of a 36 way one I have for the Samsung drive.
-
Cheers Hood
Yes Defo looks like it. Could do with using an assembly type though. Will be a nightmare to solder.
Cheers
-
Easy enough to solder if your hands are steady and eyesight good. I did mine a few years back and the eyesight was fine but now I may struggle :D
-
Hi,
the origin of these fine pitch plugs was for ribbon cables. Get a plug and crimp the cable in and your done, no soldering.
Next point is that you will not need to populate the whole thing anyway. You'll need 6 wires for the encoder, probably one analogue input,
possibly a couple of digital inputs for enable etc and a couple for error outputs for a total of 11 wires. If you had to solder them....tough get on and
do it.
I seem to recall saying earlier in this thread 'don't overlook the cost of the cables', I know I was surprised how difficult/expensive/time consuming
it was, I rather hoped you could buy all these cables new and no fuss.
Craig
-
Hi
Spoke to technical at Schneider who hadn't got a clue except they were SUB D 50. Said they will have to contact Germany for that sort of info.
Ordered from Rs now. Looking at the plugs Hood linked through the pitch on the solder terminals are 2.5mm so shouldn't be a problem with my 100x magnify glass lens. LOL
Good point Craig regarding the amount of soldering needed. Only need a few connections.
Cheers
Mick
-
Hi All
Got the connectors and back shells. The connector is split into 4 rows of pins with staggered heights which has made soldering much easier.
Here are the links and part numbers just in case anyone reading the topic needs this type of connector.
RS Components:
515-7511
https://uk.rs-online.com/web/p/scsi-connectors/5157511/?sra=pstk
176-2024
https://uk.rs-online.com/web/p/d-sub-connector-backshells/1762024/?sra=pstk
I have soldered the 6 encoder wires, the 2 VREF wires and digital input 8 (Di8) which de-powers the drive. I was going to wire this to the emergency stop.
I want to wire in another input and output but getting confused with the logic type 1 and logic type 2. There is also an option for using external 24v supply or internal supply.
What would be the better option using the CSMIO?
I have attached a couple of screenshots for ease of reference.
Cheers
Mick
-
Hi,
do you have a representative circuit diagram for the inputs and outputs of the CSMIO?
The output of the drive is just an isolated phototransistor. If the emitter is connected to 0V then the collector sinks current
whereas if the collector is connected logic high (24V in your case) then the emitter sources current. Easy and flexible.
The choice of which and whether you use the internal supply is going to be determined by the CSMIO, the drive can mange
just about any configuration.
Craig
-
Hi Craig
Thanks for your response. Yes I do. I will send tomorrow as I need to sleep. This is frying my brain. Too many parameters and options.
Cheers
-
Hi,
I've downloaded a copy of the CSMIO/IP-A manual.
I would use the 24V power supplies provided within the servo drives.
You have two servos each with its own 24V supply. It is highly likely that they will be the same but if they are not and you connected them together,
that is 0V to 0V and 24V to 24V and they are not identical they could fight each other, I would not recommend it.
I would instead use the 24V supply from one drive to power one of the photo transistor clusters of the CSMIO and use the second 24V from the other drive
to power a second but separate cluster. From page 27 and 28 if you hook the 0V and 24V outputs of one drive to pins 14 and 1 respectively of the DB25
Output connector of the CSMIO then outputs 0-3 of the CSMIO can signal inputs to the drive. In reality you probably only need one, an enable. You
could use others if you were attempting position or velocity indexing but as you are not the will be three unused outputs in that cluster.
With that arrangement the CSMIO output sources current per page 28. That would hook to the anode of the input photodiode of the drive input and the catode
would hook to 0V of its own drive.
In like fashion the 0V and 24V of the second drive would hook to pins 17 and 4 respectively providing supply for outputs 4-7. One of which would be hooked to
the anode of the input photodiode of your selected input of the drive, the cathode would hook to 0V.
Note that the outputs of the CSMIO are current limited but it looks like the current limit is 250mA, rather too much for a photodiode input. Its likely that the photodiode
input has a current limiting resistor in circuit, if not an external resistor will be required. About 5kOhm with a 24V drive will cause an active photodiode current
of about 4mA which should be enough to reliably signal across the opto barrier and still retain a sufficiently low impedance to not be noise prone.
That arrangement allows the outputs of the CSMIO to signal to the drive inputs.
Now consider the reverse. You will want at least one digital output form the drive, a fault signal. You may in fact want more than one. I have not studied
the Lexium manual but I suspect much like my Allen Bradley servo there are a number of fault conditions which can be signaled independently.
Given that you are using the CSMIO to close the position loop then you will not be concerned with a 'following error' fault from the drive. The other
two commonly signaled faults you may wish to handle separately. 'Over current' has a similar meaning to 'following error', when the commanded position
varies widely from the actual position the servo loop attempts to apply a large correction and correspondingly large current. The second fault is 'overvoltage'
which is a the primary indicator that the commanded deceleration exceeds the drives ability to absorb the braking energy. There will be other faults generated by
the drive including overheat and out of limits if so programmed but they are usually combined into one fault output.
I would again make use of the built in 24V supply of the drive. Using Type 1 logic of the previous pic:
connect the phototransitor collector (drive output) to the cathode of the CSMIO input photodiode, IN0-, pin 14, as an example, and the 24V supply of the drive to the anode
IN0+, pin1 per page 23. It would appear that there is a current limit diode in the input circuit of the CSMIO so you need not concern yourself with an external
resistor. You will have to repeat this, ie two wires to each of the CSMIO inputs you require. Make sure that the supply sourcing the output current is returning to the
same supply. That is do not use the X axis drive to supply output current for a Z axis output.
Craig
-
Hi,
I may be confusing myself, treat this with suspicion until I think it through or better still come up with a diagram:
Using Type 1 logic of the previous pic:
Craig
-
Hi,
OK, there's Type 1 logic, then there's Type 2 logic and then there's Craig's logic, and while not being partisan at all ::)
I'll do it my way....
Craig
-
Hi Craig
Thanks for the details explanation and time again. Will study your diagram this morning and revert back.
Cheers
Mick
-
Hi Craig
Some of the diagram makes sense but still a little confusing for the laymen. LOL . The CSMIO side makes more sense to me due to having pin numbers I can reference in the manual. Could you detail with pin numbers from the CN1 servo connector?
Hi All
Connected the servo to the drive and am able to jog forward and back at various speeds. Is it possible to test the 0 to 10v analog input?
I have connected the CN1 50 pin plug. I have V-Ref wires to pins 42 and 44 as the manual says.
Set operation mode to V(Velocity)
Set SPD1 and SPD0 to 0 (Deactivated) The manual states when these two parameters are deactivated the servo uses analogue input.
Set P1-40 to 3000 (Max speed for 10v)
Applying 1.5v to the VREF input but does nothing.
Any idea what other parameters I need to change?
Cheers
Mick
-
Ok making progress.
Had to set parameter p2-10 enable to 0001. (Di1)
Works now. Slight movement without any voltage applied but presume this will be down to turning?
Cheers
Mick
-
meant tuning.
-
Hi,
if you were using the setup software you have a full range of diagnostic test procedures. Note you
will have to be in position mode for the drive to do any positional indexing moves.
Once you go to velocity mode a lot of those procedures are not possible, how the drive software handles
that I don't know.
Craig
-
Hi Craig
Still waiting for the adapter cable to arrive so having to use the HDI.
Can you please clarify this. I need to understand the wiring diagrams in the manual. I'll just use DI1 as an example.
Example of digital input with internal power supply (logic type 1):
Vdd pin 17 connects to DI1- pin 9 (Through a relay)
COM+ pin 11 connects to COM- pins 47,48 or 49.
Example of digital input (logic type 2) with internal power supply
VDD pin 17 connects to COM+ pin 11
DI1-pin 9 connects to COM- pins 47,48 or 49 (Through a relay)
Cheers
Mick
-
Hi,
Vdd pin 17 connects to DI1- pin 9 (Through a relay)
No, that is incorrect. Forget Type1/ Type2 for the moment. The switch contact is more a symbol than actual, no relays here.....relays are for cavemen. Your
'switch' is going to be the phototransistor of the CSMIO. Note that the output cluster of the CSMIO requires a 24V supply and the outputs source current.
Follow the pic attached. 24V supply from the drive (purple highlight) to the output cluster in the CSMIO, output0 of the cluster to the anode of the drive input photodiode,
(orange highlight), and then from the cathode of the photodiode to 0V (pruple highlight).
Don't know what to call it, type1 or type2, better it be Mick's way. If you understand it and it works that's the right way!
Craig
-
Hi,
added some pin numbers.
Craig
-
Hi
Your switch is going to be the phototransistor
I was aware of this, I just wanted to concentrate on the servo side.
Using DI1 as an example.
output0 of the cluster to the anode of the drive input photodiode.
Is this pin 9 or 11?
and then from the cathode of the photodiode to 0V (purple highlight).
Is this pin 45, 47 or 49?
Cheers
-
Hi,
output0 of the cluster to the anode of the drive input photodiode.
Is this pin 9 or 11?
According to the pic from the manual you attached its pin 9.
and then from the cathode of the photodiode to 0V (purple highlight).
Is this pin 45, 47 or 49?
Likewise from the same pic the cathode, common to all four DI's, is pin 11 called COM+ and that will be connected to pin 45 or 47 or 49 by an external wire with
your handy soldering iron.
Craig
-
Thank you
Makes some sort of sense now.LOL
Cheers
-
Hi,
I personally think the choice of names for the photodiode terminals is poor.
If the intention is to drive current through the photodiode then pin 9 should be called DI+ and the cathode common could have been called
DI- or COM- or something. The choices the Germans have made (DI- and COM+) are confusing.
Craig
-
Craig if you're confused I need to throw these servos in the bin. ;D. What chance do I have? I can build a house with my eyes closed but all this electronic terminology is as confusing as hell.
Cheers
-
Hi,
these modern servos pack in so much stuff, you'll be blown away once you get the software running.
In some respects you are making life more difficult for yourself with the analogue CSMIO controller, you now have the drive closing the acceleration
and velocity loops with the CSMIO closing the position loop. With a step/direction controller the entire servo loop is closed by the drive and a number
of control features come into play which cannot happen with control split over the drive and CSMIO. I refer to indexing position and/or speed.
My Allen Bradley servo allows you to select two control modes, say step/direction position mode and analogue velocity mode, either of which can be selected
by asserting one digital input. Really handy, assert one input and my servo turns from a free running voltage controlled motor to a high torque indexable
servo with a resolution of 5 arc min.
Anyway the chances are these servos will be in the family for many years and no doubt you will get to sample how they do with an open loop step/direction control.
Craig
-
Hi Craig
With reference using a 5k resistor from the CSMIO to the servo input. I can't find anything in the manual that says it has a current limiter in the servo input circuit. Can only see the information on the attached screenshot. Should I wire in a 5k resistor on that 24v line from CSMIO to the Input?
Cheers
-
Hi.
no. It looks like the manufacturer has included a current limit resistor in the input circuit. The pic is from one you
posted earlier.
Craig
-
Hi,
as I say the manufacturer has thought of everything. The current limit resistor is built in and there is an antiparallel diode over the photodiode
to prevent excess reverse bias destroying the photodiode.
Photodiodes and LEDs are like regular diodes, they conduct current in one direction but block current in the reverse direction. The problem is they
can usually block on 5V or less in the reverse direction. If you exceed 5V reverse bias the photodiode will go into reverse breakdown. Assuming adequate
current limiting it wont destroy it but it will get hot....always a bad look for any silicon device.
To counter that shortcoming the manufacturer has put a regular diode across the photodiode so that the worst reverse bias it will experience is the
forward voltage drop of the regular diode. These two simple things have made the input circuit reasonably safe from misapplication.
Craig
-
Hi Craig
Thanks nice and simple then. My next question was what are tihose two diodes for.
Connected the z axis up earlier earlier. Can jog at ridiculas speeds way above what I need.
Auto tuned no issues. ;D
Cheers
-
Hi,
Ridiculous speed is good! As is UNTOLD acceleration!!!
In truth fastest maximum speed is less telling than acceleration. May I suggest an experiment where yo keep upping
the acceleration in Mach until you get an overcurrent fault. That will be the true measure of what these servos can do.
Craig
-
Hi Craig
Yes will give it a go when I get back on Thursday. Working away for a few days in Bournemouth. :( I need to have a read up on the encoder set up and what steps to set in mach. I believe the encoders have 1280000 pulses per revolution? If so would mean 256,000 steps per MM in mach. Seems too high to me!
Cheers
Mick
-
Hi,
yes it is very common for encoders to have very high resolutions.
Delta 17 bit absolute encoders are 131072 count per rev.
Delta 20 bit incremental are 1048576 count per rev
Delta 24 bit multi turn can have +128 to -127 turns and 65536 count per rev within any given turn.
The encoder outputs to the CSMIO will be synthesized from the raw encoder. Thus it is very unlikely that you would choose to have such
a high resolution, way more than is practical unless you like to brag and 'do something that your mother warned you would make you go blind'.
Craig
-
Hi
So can you set the encoder resolution or is it Fixed?
Cheers
-
Hi,
the encoder in the servo is fixed and the drive is setup to handle the resolution.
The encoder outputs from the drive to the CSMIO are synthesized. They can be programmed at different resolution.
Craig
-
Hi,
finally found the setting.
Note the factory setting is 2048 line per rev or 8192 counts per rev.
Its not clear to me from the table entry that it can be adjusted. The fact that it is a RW variable suggests that you can set it but equally the lack
of max or min data values suggest that it is fixed. Either way 8192 counts per rev is useful middle ground.
At max servo speed, 3000 rpm or 50 rev per second, the line frequency is:
Fline= 50 X 2048
=102.4 kHz
This will be the maximum frequency of the A/B quadrature signals to the CSMIO encoder inputs. 100 kHz is quick but not too difficult. Twisted pair differential
signaling is provided and should work well here.
If your leadscrews are 5mm per rev and your servos are 1:1 coupled to the leadscrews the resolution at 8192 counts/rev is:
resolution (linear)= 1/ 8192 X 5
=0.6 um
Sub micron resolution is very good and still the encoder line frequencies are realistic. In short even if the resolution of the synthesized encoder is not
programmable the choice made by the manufacturer is right in the sweet zone with respect to resolution and signal frequency.
Craig
-
Hi Craig
Thanks for digging that out. I think that level of accuracy is way above what I need or could measure. 0.6um is 0.0006mm.
0.01mm is where I am with my dial and vernier gauges. Lol
Cheers Again
Mick
-
Hi,
if that is the case, and the parameter is adjustable? then I would set it to 1250 line per rev
which corresponds to 5000 counts per rev.
With 1:1 coupled leadscrews at 5mm pitch then the resolution is 1um, an easy number to deal with.
The steps per unit (mm) in Mach would be 1000, easy. Set the max velocity in Mach at 5000 units/min
ie 5m/min. That would mean that Mach and the CSMIO would demand no more than 1000 rpm
from your servo.
Set the acceleration as high as is practical, excessive acceleration will cause over current events, so you
want to back off by 25% or so from that.
At 1000 rpm and 1250 lines/rev the A/B quadrature signals would be 21kHz, real easy going.
Craig
-
Hi
Found this on scaling in the manual. Section 7.3.4.2 (screenshots below) I think this may be something to do with the resolution of the encoder.
I don't fully understand PUU.
I spoke to S/T yesterday who said the resolution of the encoder is changed via parameter P5-16
P5-16 AXEN
Encoder Increments in PUU Applicable operating mode: PT, PS, V, T Setting can only be changed if power stage is disabled.
PUU -2147483647 0 2147483647 Decimal
s32 RW
Cheers
-
Hi Craig
Parameter P1-46 is adjustable from the drive.
Will get back to you later with the acceleration tests.
Cheers
-
Hi,
you must have a different manual than I, I haven't seen those pages before. I believe they relate to electronic gearing
and is important in step/direction mode but irrelevant in analogue velocity mode.
P1-46 is the encoder output pulse resolution and is separate to electronic gearing.
Craig
-
Hi,
I've just been looking more closely at the manual I have and the pages you linked are there. I was not concentrating on those as they relate
to pulse input whereas you are planning on analogue input.
You concern is how the simulated encoder outputs (to the CSMIO) relate to the absolute encoder on the servo motor.
Craig
-
Hi
Need to put worrying about the encoder outputs resolution on hold for a minute.
Connected the encoder and Vref to the CSMIO. Seemed to be working ok then tripped the electric and now the drive powers up but seems to be locked with the fan continuously running. Been on the phone to Schneider technical for over an hour who were as much help as my Misses would be. >:( Literally only sent the Z axis home a few times at slow speeds as was having an issue with the homing not working right.
I have not got a clue where to start or what has caused it. Help please!!
Cheers
-
Hi,
that doesn't sound too good. You say 'the electric tripped', does this mean the circuit breakers of your 230VAC supply?
That should not happen and may be an early life failure. If you want to claim warranty which I think is reasonable then you can't
pull it to bits. If you did you'd measure the DC link voltage. I would also check that all six inverter IGBT's were not shorted nor the
brake IGBT.
Craig
-
Hi Craig
Yes the 240v breaker. Will have to send it back. Can set the other drive up but just concerned that something is wired wrong. Got the cable for the Somove now so will plug it in tomorrow and see what it says.
Cheeers
-
Hi,
in order to take out the breaker the DC Link has to short and as you describe the drive still powers up so the fault is unlikely the rectifier
or pre-charge components of the DC Link circuit.
Referring to the diagram attached if two 'opposing' IGBTs conduct simultaneously, for example the two highlighted, the DC Link would
short and certainly take out the breaker. The build up of current is that rapid and aggressive that the damage is unrecoverable.
As a matter of design that two IGBTs should conduct in that manner is an absolute failure, usually indicating a fault in one or both IGBTs. Its
extremely unlikely the control system would trigger both IGBTs together and certainly nothing you can do would cause it. If you have correctly
connected the servo, and from your description you had, otherwise it would not have worked initially, then there is no way your 'wiring'
could have caused it.
The only other possibility is if the Brake Resistor is shorted. If so, then the Brake IGBT conducts it would short the DC Link and cause a failure.
Do you have an external brake resistor? In its absence you did not install a link or short of any description?
By my reasoning if you have hooked up the servo correctly and not tried to back feed the drive with AC or DC or some other extraneous
condition, and you have not shorted the brake resistor then there is no condition that you have caused which could destroy the power section.
I conclude therefore that one or more components were faulty from manufacture and 'suffered an early life failure' as such faults are described.
Craig
-
Hi Craig
Thanks for the explanation. I agree it would not be a wiring issue. The connections to the mains are clearly marked on the plugs (Except for it gives you R1 and R2 for live and neutral. I wired live to R1). It is impossible to wire the motor to drive wrong with pre-fab cables and the motor was jogging with no issues before I went away. (This was using the servo control panel) I was thinking more so with the connections coming from the CN1 50 pin plug.
I don't have an external brake resistor connected. According to the manual (Screen Shot attached), there is an internal braking resistor on CN7 but it looks a jumper wire has to be connected to activate it. But it also states the internal braking resistor is activated when shipped.
Internal braking resistor A braking resistor is integrated in the device to absorb braking energy. The device is shipped with the internal braking resistor active.
Would there be any specific parameters that would need setting or de-activating that may have caused this?
Cheers
Mick
-
Hi,
I was thinking more so with the connections coming from the CN1 50 pin plug.
I imagine that there is any number of ways that you could miswire CN1 that might even wreck the input/output circuitry of CN1 but
that could not cause a short in the power section.
Would there be any specific parameters that would need setting or de-activating that may have caused this?
There again there might be any number of possibilities for it not to work but absolutely none of them should cause a fault in the power section.
Craig
-
Hi Craig
Thanks for the info. After taking a look at the CN7 plug I have noticed that the jumper wire for the Internal Brake is pre-connected. Should this have been disconnected prior to use?
I have connected the SoMove to the drive and have attached the Faults listed in the memory. I have tried clearing all the faults but when you try and enable the drive it brings them back.
Cheers
-
Hi Mick,
After taking a look at the CN7 plug I have noticed that the jumper wire for the Internal Brake is pre-connected. Should this have been disconnected prior to use?
No, according to the pic you posted earlier the installed link is for the internal resistor. If you have not disturbed it then it should be correct.
As I view it you could miswire that link so that there is no resistor either external or internal and that could cause a damaging fault. If you have not touched
it however it seems unlikely.
Those shots of So Move screens suggest that the software is very slick.
I'm not surprised that you cannot erase the error log, what would be the point of retaining a log only to have a customer erase it at will? The log
looks like a buffer, as more recent errors or warnings occur the old error codes will drop out the bottom.
The only one which surprises me is the foldback current error. From what you have described there is no way you could cause the servo
to absorb enough current that current foldback became active in the drive. That would be the instant the drive 'threw a leg out of bed' I guess.
Craig
-
Hi
I will speak to Schneider tomorrow and send the drive back. I'll put another drive on order and hopefully get a refund.
Thanks for looking at this.
Mick
-
Hi Mick,
what did Schnieder decide to do?
Craig
-
Hi Craig
New drive coming this week. No questions asked but had to send the old drive back so they can test it.
Cheers
Mick
-
Hi Mick,
kool.
Nice to know they back their gear, of course it would be nicer that it didn't blow in the first place,
but replacing it without question comes a close second.
Craig
-
Totally agree.
Going back to the spindle debate. What do you think about using 2 X 1.5kw motors on the spindle? Instead of a 3kw 3 phase.
Cheers
-
Hi,
why?
First: two 1.5kW servo drives which have the same power factor as one 3kW drive will draw the same current.
Second: if the motors were running in torque or velocity mode then its probable you could get them to share the load.
If running a closed position loop then they won't share the load, one servo will always be a few arc minutes ahead (or behind)
its partner and will therefore have to provide the lions share of the effort.
Third: is the price of two 1.5kW servos and drives cheaper than one 3kW servo and drive?. I think the price would favour one large
servo/drive. DO NOT LET THE MISSUS READ THIS OR YOU ARE SUNK!!!
Craig
-
Hi Craig
First: two 1.5kW servo drives which have the same power factor as one 3kW drive will draw the same current.
I'm not concerned about the power factor.
Second: if the motors were running in torque or velocity mode then its probable you could get them to share the load.
If running a closed position loop then they won't share the load, one servo will always be a few arc minutes ahead (or behind)
its partner and will therefore have to provide the lions share of the effort.
Can you expand on this?
Third: is the price of two 1.5kW servos and drives cheaper than one 3kW servo and drive?. I think the price would favour one large
servo/drive. DO NOT LET THE MISSUS READ THIS OR YOU ARE SUNK!!!
The price is very similar.
The thing that is bugging me is the phase converter. The company I bought it from are no longer selling these units. They still offer a repair service at the moment but not sure how long for. What I can sell the phase converter for would go a long way to paying for the spindle set up. Old ground but if I wanted to sell the lathe it would be more saleable as a single phase machine. No, I'm not thinking of selling it.
Just exploring and want to make sure I cant use single phase set up before ordering the 3 phase motor and drive.
Mick
-
Hi,
imagine for instance that one servo is mounted 1 degree rotated in its mount relative to its
partner.
When trying to share load when executing an indexed move (position), the leading servo will try to be at 900
at moment t=nnn.nnn and likewise servo 2 will try to be at 900 at the same time. However the leading
servo will actually be at 910 at time t=nnn.nnn. The trailing servo will treat this as the load advancing
on its ideal commanded position and therefore try to retard the leading servo.
This was an artificial construction to illustrate the idea, but any two position servos will inevitably be slightly different
to each other, and if that error differs by more than the 'zero error window' they will fight each other.
In torque they should share equally. In velocity mode imagine one servo is programmed to be a fraction faster than the other.
Which servo powers the load and would not the slower servo be dragging the faster one? There again I have made a
worst case to illustrate the idea but two velocity servos are never going to be identical. What happens to load
sharing then?
I'm not concerned about the power factor.
Yet!!!
Craig
-
Hi Craig
Makes sense.
Cheers
Mick
-
Hi,
if you want 3kW single phase then go Allen Bradley 2098-DSD-030 and matching servo and
be prepared to pay extra for the line reactor/filters.
It is the biggest single phase servo drive I know of.
The only other alternative is to strip the DC link circuitry off a three phase 230V drive and make your own DC llink,
you will almost certainly need buck/boost PFC correction beyond 3 kW but in theory you could make it whatever
size you want
Craig
-
Wouldn't be the way I would go (2 motors) and not sure if your drives support it but if they do then slaving the second drive to the master may work.
Could be called Master/Slave, Electronic Gearing, Master/Follower etc.
-
Hi Hood,
master/slave works really well on a gantry say with two ballscrews but Mick is talking about
having two servos locked together on one shaft. I think thats a good way to generate a lot
of expensive smoke.
Craig
-
I am talking about it being done in the drives rather than Mach, one drive controlled from Mach, the second follows the first by using master/follower mode..
I once messed about with it and the AB drives and it worked well, was sync'ing a live tool to the spindle for cutting Hex etc, can't recall the name of it at the moment, so not the same thing as being proposed here.
As said though it is not a route I would choose, just inviting issues to rear their ugly head.
Edit, Polygon turning was the thing I was trying to remember the name of. Not relevant to this discussion other than I used Follower mode for it.
-
Hi
Craig
Making my own drive is way above my level and a route I am not prepared to take.
Hood
Thanks for your comments. There is a reference to Master/slave in the manual but very limited info.
I think this is a none starter going by both of your comments or at best something which will cause more issues than its worth.
I'll reluctantly stick with the phase converter and order a 3 phase motor.
Thanks again.
Mick
-
Hi Mick,
go on......where's your sense of adventure!!! There's nothing more exciting than having 585V DC link
capacitors discharge in front of your face in a shower of sparks, smoke and molten metal.
It makes your heart pump really fast....and thats got to be good for your health. ;D
In truth its not quite as difficult as it seems, there is a large body of published literature on the subject
of active PFC.
Depending on your drive you could instead of hooking three phase wires to it hook two DC wires of your home brew
boost PFC single phase DC power supply. I work for a company that repairs industrial welding equipment
I could walk around the workshop and pick up all the secondhand parts I need within the hour. A $50US
Texas Instruments Lauch XL microcontroller board and your in business, and I wouldn't be stopping at 3kW,
I'd be aiming at 5kW cont and 10kW 10 sec overload.
-
Hi Craig
Lol. It's a nice idea but not at the moment. I'll give you a shout if I change my mind.
Any idea why I'm getting slight movement when the drives are enabled? Auto tuned the drives but not tuned the CSMIO yet.
Cheers
Mick
-
Hi Mick,
your servos are in velocity mode. An analogue voltage at the input will cause the servo to rotate. It is tunable, something like
300 rpm per volt. Even when there is no input voltage there is still electrical noise, thermal noise if nothing else, that's a fact of physics
and you could end up with some net small voltage which will cause rotation.
When you hook up the CSMIO it will close the position loop. Thus if Mach commands 3184 steps, say, or 114.6240 past the index point and
should the servo drift a few tenths of a degree due to noise then the CISMO will detect that the servo is not at its commanded location and make a voltage
correction such that the servo moves back towards 114.6240 again.
If your servo were in position mode it would not rotate at idle, the position loop is now in the servo drive but it has the same result as the CSMIO, namely any drift
will be detected and a restorative action will be taken by the drive.
Craig
-
Thanks Craig
The motor is turning at about 3 rpm without any voltage connected. With the DC motors this was adjusted by the potentiometer on the drive. I will read through the manual tuning section to see if anymore info is given. Doesn't say anything regarding this using the autotune method. I understand what you saying regarding closing the loop but seems a lot for the CSMIO to keep correcting.
Please forgive me if that was a stupid comment.
Cheers
Mick
-
Hi,
3 rpm represents an effective input voltage of:
Vin=3 /300 (rpm/V)
=0.01V or 10mV
That could be the input bias voltage of the input amplifier alone. You can chase your tail for hours and then the temperature changes and its out
again. Close the position loop already!
Craig
-
Hi
Good news so far nothing blown up. lol
As mentioned before without any power connected to the Vref I get very slow movement of about 3 rpm. Not a major issue.
Connected up to the CSMIO on Dac output 0. Pins 1 and 14 on the Analog I/O connector. When I enable the drive the motor turns at around 60 rpm. I have around 200mv on pins 1 and 14 without any speed command.
I have autotuned the drive without the CSMIO connected which worked fine.
Craig
I take on board what you said about the CSMIO closing the loop and rectifying this issue but this is not happening. I am unable to autotune through the CSMIO. It is making it impossible to try different setting within the drive when it moving the motor at approx 300mm/minute as soon as enabled.
I am also not able to index the motor. If I do a reference home from Mach the motor moves in the right direction but ignores the home switch.
Any Ideas
Cheers
-
Hi,
the CSMIO is not working as it should.
Do you have the means, either an oscilloscope or software within the CSMIO to monitor the synthesized encoder outputs from the drive?
Another idea just to test would be to disconnect the CSMIO altogether and set the servo drive in position mode. The manufacturers servo loop
is going to be a snap by comparison to closing it with the CSMIO.
Craig
-
Hi
I haven't got an oscilloscope but there is one within the CSMIO. I wouldn't have a clue what I am looking for.
What would you suggest doing once I put the drive into Position mode?
Mick
-
Hi,
if you wish the CSMIO to close the loop then the servo drive will have to produce encoder signals
to the CSMIO correctly. That is the first step, you must confirm that the servo drive is producing
the right encoder signals.
If you put the servo drive into position mode, then without pulse input the servo should stop and
stay that way. It confirms that the position loop is providing a correction such that the velocity is
zero and overcoming the slight bias voltage.
If you had a simple step/direction controller, even a plain parallel port you could control your servo
easily.
Craig
-
Try inverting the encoder direction in the plugin.
-
Hood
Thanks. Will try tomorrow.
Mick
-
Hi Mick,
by using the CSMIO you have added a layer of complexity that is making your job impossible.
You don't know whether its Mach, the CSMIO or the servo/drive and you are floundering.
Disconnect the CSMIO, put the servo drive in position mode and manually pulse the step input
to confirm the servo and drive operate correctly. If and when you get the servo and drive operating
THEN add the CSMIO, without Mach to start with.
If you don't have a signal generator to pulse the step input get a rotary encoder and use one channel
and spin it for all its worth. You will have to use electronic gearing to get useful results, a good learning
curve in itself.
Craig
-
Hi Craig
Yes this is confusing me somewhat.
I'll try what Hood suggested then look at your suggestion.
Reason being is I will have add addition wires to the Cn1 connector to try this.
I do have the old MPG wheel which I think I could use as a pulse generator.
Mick
-
Hi,
you've also got the tuning/setup software. In position mode you can program indexed moves, you don't even need wires
on the pulse inputs.
I don't know what you are doing wrong, surely the programmed current limits would prevent the drive from drawing enough current
to trip your breaker. Either way I would not hook up the CSMIO until I was 100% that the drive and servo were perfect, including sensible
current limits.
Schnieder were good enough to replace one drive....how do you think you would go asking for a second?
Craig
-
Hi Craig
Not really sure what you saying.
I can't contact Schneider and say I want another drive when there's nothing wrong with the ones I have.
As far as programmed current limits. This is set in P1-78.
It's factory set at 19amp. Which is possibly why the first drive gave up. I wasn't aware I need to change that parameter. It's now set to 13.5amp motor max current.
I am able to use the software and jog with no issues and autotune.
Mick
-
Hi,
use the tuning software to set up a series of indexed moves. You should also be able to set a number of free running speeds.
Craig
-
Hi,
It's now set to 13.5amp motor max current.
I think this is still way WAY too high. If I'm not mistaken that is the per phase current.....13.5A per phase!!!
Do the calculation:
DC Link current= 3 (phases) X 13.5 (A per phase) / (square root 3)
=23.4A
Single phase input current= DC Link current / power factor
=23.4 / 0.5
=46.8A
Its no bloody wonder you 'trip the electric'. Reduce the max current down to a couple of amps.....once you get things sorted then increase it to somewhere
close to maximum. Remember you are trying to use an external controller to close the loop, the CSMIO, and it is highly probable during the set up you will
have maximum current events, so why have the max set at a value that threatens to damage the drive, the servo and your power supply. This is supposed
to be a 1hp axis servo......not the motor that powers the earth around the sun!
Next issue is that there are four parameters that set the maximum current, P1-78 through P1-81, ILIM,IMAX,DIPEAK, and DICONT. Not 100% sure what they all mean
yet, but I bloody well know none of them should be 13.5A!!!!
Craig
-
Hi,
the drive data suggests 4.5Arms at continuous rated current, probably per phase.
It also suggests 13.5A rmsmaximum current.
Try:
DICONT=4.5
DIMAX=13.5
ILIM=4.5
IMAX=4.5
Craig
-
Hi Craig
Yes that's what they are set to now.
Mick
-
Hood/ Craig
Tried inverting the encoder signals and still the same. Any thoughts?
I cant index the machine. The limit switches work fine but when I send the axis home it's ignoring them and the motor doesn't stop.
I also can't control the speed of homing. Even if I have it at 1% its way too fast. I had to put the max velocity to approx 100mm min to slow it down. Then its still fairly fast.
Mick
-
Hi,
I cant index the machine. The limit switches work fine but when I send the axis home it's ignoring them and the motor doesn't stop.
I also can't control the speed of homing.
These are Mach issues...don't worry about those until you have got the CSMIO and servo/drive loop sorted.
You should be able to issue MDI commands of the type G0 X100, G0 X0 etc. Can and does the CSMIO close the loop accurately and using the software
scope of the CSMIO what does the step error look like?
Craig
-
Hi
Its impossible to give commands through the MDI when the axis is moving as soon as its enabled. I've tried autotuning the CSMIO and there is a step error but the axis position is always 0. I believe this is because the axis has not been set to 0 (Homed)
I need to eliminate the axis moving once enabled to be able to try any movements through the MDI. Whilst autotuning the axis is going mad jumping around with large movements unlike what it did when tuning the DC drives. This couldn't be anything to do with steps per revolution being way off could it?
Mick
-
Hi,
take the belt off so the axis doesn't move.
You have yet to devise a means of establishing the the synthesized encoder signals from the
drive are indeed being correctly generated.
If you refuse to put the drive in position mode then I can't help you devise any strategy.
Craig
-
With the drive disabled and in the plugin PID tuning page , do you see the encoder counts increasing/decreasing when you manually rotate the motor?
-
Hi
Will check in the morning.
Mick
-
You shouldn't really even need to go into the Plugin page to see as the position in Mach should change as you rotate the motor but the plugin would probably be better.
If you do see it move in the plugin then check how many counts it sees per rev and see if that coinsides with the value you have entered in the Axis page in the plugin.
If that all checks out you could try pressing the DAC offset button to see if that will hold the axis steady.
-
Hi
Adjusting the DAC offset has solved the motor running away. ;) Now stands still. Set this at 0.04
With the drive disabled, turning the motor shaft gives no reading either in the CSMIO PID or Mach. The axis digits flicker from 0 to 1 but nothing more. :(
Mick
-
Good News :)
Striped the Cn1 plug back to check the encoder wiring and I had connected A+ to pin 20 instead of pin 22 ::)
The DRO in Mach and in the PID are now working correctly.
Bad News.
Still unable to home the axis. The home switch is not being seen. If I run a program through the MDI Mach gets to the desired position and stops but the motor continues moving.?
Mick
-
Great news ;D ;D
Autotuned the CSMIO and bingo. All working spot on. The first autotune was done with the servo drive on a low max rpm. Everything worked great until I tried to raise the velocity in Mach to a sensible speed. Loads of vibration. Adjusting the max rpm in the drive made no difference.
Set the drive to max rpm of 1000 which give me 5m minute and re-autotuned the CSMIO. No issues at all. Home switches work and runs programmes through the MDI no problem.
I presume the tuning uses the limits set within the drive?
Thanks, Craig and Hood for spending time on this. Its well appreciated.
I'll fit the X-axis now. LOL ;)
Cheers
Mick
-
Hi,
good news.
Set the drive to max rpm of 1000 which give me 5m minute and re-autotuned the CSMIO
I think this is a mistake, the drive and servo should be programmed for maximum speed (3000rpm) but the 5m/min axis speed limitation
should be in Mach.
A max servo speed setting is useful if there is some VNE (velocity never exceeded) like leadscrew whip or voltage overload on deceleration
for instance. Normal axis speed settings are rightly the province of the motion planner, Mach in this case.
Craig
-
Hi
Can anyone explain the acceleration setting in Mach.
E.g. 1000/s/s
What exactly does that equate to?
Is it 1000/60/60 Which would be 0.27 seconds to reach velocity target.
My drive is factory set to reach desired velocity in 30mili secs.
Mick
-
Hi,
good news.
Set the drive to max rpm of 1000 which give me 5m minute and re-autotuned the CSMIO
I think this is a mistake, the drive and servo should be programmed for maximum speed (3000rpm) but the 5m/min axis speed limitation
should be in Mach.
A max servo speed setting is useful if there is some VNE (velocity never exceeded) like leadscrew whip or voltage overload on deceleration
for instance. Normal axis speed settings are rightly the province of the motion planner, Mach in this case.
Craig
Not sure I agree with this. I have had first hand experience of mismatched velocities causing issues. I was helping a friend retrofit a lathe and we had a servo on the turret. He had the drive set at the default 4000rpm but in Mach it was set to the equivalent of maybe 1000 RPM. He just could not tune it, when I told him to drop the drive down to the equivalent rpm the tuning was easy. Now there was a large disparity between the two rpms initially and a smaller difference may not matter but I personally think a match is the best route.
Hi
Can anyone explain the acceleration setting in Mach.
E.g. 1000/s/s
What exactly does that equate to?
Is it 1000/60/60 Which would be 0.27 seconds to reach velocity target.
My drive is factory set to reach desired velocity in 30mili secs.
Mick
The acceleration in the drive will be of no consequence as you are using Mach to command the drive so the acceleration will be at the rate set in Mach and not the drive.
As for 1000mm/s/s it simply means the axis will accelerate and reach 1000mm/s in one second, 2000mm/s in 2 seconds etc. Your Velocity is set in Mach in mm/min so 1000mm/min velocity will be 1000/60 = 16.7mm/s With an accel of 1000mm/s/s you would reach your 1000mm/min in 0.017seconds
-
Hi Hood
Cheers on both comments. Sort of makes sense. Need to read it a few more times had a busy day.
Mick
-
Hi Hood
So using 1000rpm as an example as this is what my drive max velocity is set to. The calculation is 1/60 =0.017 seconds. Should I set my drive to reach max speed in 17ms also as opposed to 30ms?
Cheers
Mick
-
Acceleration is velocity over time, so in Mach velocity is in Units per minute and acceleration is units per second per second.
So first thing you need to do for the calculation is change the set velocity from units per minute to units per second.
So for your example 1000 units per minute it would be 1000/60 = 16.666666667 units per second.
Ok so now we know the velocity in Units per second we can work out how long it will take to get there with the acceleration you have set in Mach.
So you say you have 1000 units/s/s acceleration. That means it will get to a velocity of 1000 units per second in 1 second.
That is way faster than your velocity however as your velocity is 1000 upm so only 16.66667 units per second.
So to get the time it will take to get to your velocity you can work it out a few ways, one is to just simply divide your units per second velocity by the acceleration, so 16.66666667/1000 = 0.016666666667 seconds to get to max velocity.
You mention RPM however so I am not sure exactly what you are meaning. Obviously the rpm is the max value in the drive but what do you actually have in Mach? If you have 1000 set for the Velocity then that will not be 1000rpm at the motor unless your ballscrew was 1mm pitch which is unlikely. So say it is 5mm pitch then that would mean for 1 rev of the motor you would move 5mm so the velocity in mach for a motor rpm of 1000 would be 5000mm/min.
If that is the case then the time to get to max velocity would be
5000/60 = 0.08333333333333 seconds.
Regarding the value for accel set in the drive, I do not think it will matter at all. I think that setting will be used only when there is an internal drive command such as indexing or internal speed command etc.
As you are controlling the drive via the analogue inputs (step/dir would be the same) then you are also controlling the velocity via that method and thus the setting in the drive is irrelevant.
-
My last calc above has a bit missing ::)
It should read 5000/60/1000 = 0.08333333333333
-
That makes total sense now.
I have the max rpm set in the drive at 1000rpm. I have the velocity set in Mach at 5000mm min which gives me 1000rpm max speed of the motor using 5mm ball screws.
So like you have worked out the 5000/60/1000=0.083. Which is slower than the drive setting of 0.030.
The manual is saying parameter 1-34 sets the acceleration if in velocity or PT mode. Screenshot attached.
I'll try setting 1-34 to something a lot higher to see if it does affect the acceleration.
Am I right in thinking if it does then settings in Mach would not be accurate outside the drive limits.
Mick
-
Hi,
if you set Machs velocity and/or acceleration higher than the servo/drive then when Mach issues a max velocity positional move,
ie a G0 then the servo cant keep up and will fault out 'following error'.
At all times the servo/drive must be at least as capable as Mach expects. In fact the higher the acceleration of the servo/drive
the better it can follow the commanded input.
It is for this reason that I advocate the servo/dive be programmed for its maximum practical velocity and acceleration.
Note that as the forward gain (velocity/acceleration) is increased if there is a fixed phase lag in the drive chain, the encoder for instance,
then the phase margin reduces and may become unstable. Hood has already described that situation. Even if the velocity/acceleration
commanded by Mach is less than the servo/drive and that the servo/drive loop has an instability (low or vanishing phase margin) the
instability will be excited. It is not because Mach has commanded an impossible move but rather the servo/drive has an instability.
It is for this reason that much is made of self tuning notch filters...they can restore phase margin without undue reduction in forward gain.
By reducing the maximum velocity (or acceleration) of the servo you are in effect throwing away forward gain......ie you bought a servo that has 'sports car'
performance but you throttle it back so it performs like a 'Morris 1000'.
Craig
-
Hi All
Had to take the wife away for a week so sorry for no update.
All good set the X-Axis up now and no issues what so ever. Done several tests with my 0.01mm gauge and see no error at all on both Z and X. Would be interesting to get a 0.001 gauge to test.
As previously discussed with acceleration. I can set the acceleration way above what is set in the drive and it does not fault out. So I think Hood was right in his previous comment.
Need to get the spindle sorted now and torn between exploring further the two motor options or 3 phase Lexium 32. This is totally off-topic so will start a new topic over the weekend.
Thanks again to Hood, Craig and everyone else who commented.
Cheers
Mick