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Author Topic: Motor tunning  (Read 9446 times)

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Offline Hood

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Re: Motor tunning
« Reply #20 on: October 08, 2011, 05:09:03 PM »
You should manage to get the max velocity that your voltage/motors allow, not sure what that is as dont think you actually said what the rated voltage/rpm was but we know what voltage you are using so can work it out near enough. One thing though, is the 50v you mentioned earlier AC or DC?

What size machine is this on?
What are ALL the specs of the motors?
It could be the Geckos are just not capable enough for the current requirements of the motor but until you post the specs I cant really say.

One last thing, to me accel is more important than Velocity, Velocity is nice as well so if you can get both all the better but you may be farting against thunder to get both  depending on how well the machine/motors and drives are matched.
Hood
Re: Motor tunning
« Reply #21 on: October 09, 2011, 12:26:04 PM »
Hood
The motors run on DC 50 V the machine is a full size floor model 3 phase 5 hp , the servos are the Big MHO by baldor motion specs are 120 V/ DC, 500 in ozs torque, 39 amps, no load speed 31902 this is everything on the motor spec label other then the part #.

Dennis

Offline Hood

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Re: Motor tunning
« Reply #22 on: October 09, 2011, 01:38:16 PM »
31902 rpm ?

Hood
Re: Motor tunning
« Reply #23 on: October 10, 2011, 02:21:57 PM »
Free rpm no load thats what it says on the label anyway, In no way dose the motor spin this rpm while the machine is running.

Dennis

Offline Hood

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Re: Motor tunning
« Reply #24 on: October 10, 2011, 03:58:55 PM »
Well never seen that before on a motor, usually it has a rated RPM for the rated voltage or sometimes a voltage constant. 31thousand RPM is fast ::) Could see if it was 3190 at 120v.
Do you have a link to info on the motors?

The problem may well be over current fault on the drive, if you are trying to push things too fast at too great an accel its possible the Gecko is tripping on over current as I think they are only 20Amp or so, not sure if they will just limit the current to that or if the motor asks for more it may trip out. If it just limits then its possible its a following error fault as the motor requires more amps than the geckos will give so it doesnt get to where its meant to be in the time frame required and thus you get a following error.

Hood
Re: Motor tunning
« Reply #25 on: October 10, 2011, 05:39:59 PM »
Hood
The motors are 120 V DC this must be the why they have that spec, it may very well be that the drives are not capable of anything more then i am getting as they are rated for a max of 70 V the new ones are now rated for 80 volts originally the motor's were running at 100 V DC.
I did check with a transformer company and they advised me that there would not be much difference between the 50 V DC i was using and a new transformer with 70 V DC so i didn't change anything i really don't want to rewire the machine to use larger drives plus the money thing's being the way they are right now tight on cash.

Dennis 

Offline Hood

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Re: Motor tunning
« Reply #26 on: October 10, 2011, 05:53:48 PM »
Voltage will give you RPM so the more volts the faster RPM you will get on a DC Servo.
I think it may be the current that is your problem.

Hood

Offline BR549

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Re: Motor tunning
« Reply #27 on: October 10, 2011, 06:17:06 PM »
I think Hood hit the nail on the head.

The motors are rated at 120v X39a = 4680 watts of power

You are running them at 50v X20a = 1000 watts of power.

IF the machine design NEEDS that 4680watts  to work correctly
then 1000 watt may be causing the problem.  Following errors the motor can no longer keep up to the demand.

YOU COULD gear down the feedsTo get more torque BUT you then loose speed.

BUT at least you can run the machine and do work. It just may take longer.

Just a thought,(;-) TP
Re: Motor tunning
« Reply #28 on: October 11, 2011, 12:16:02 PM »
Thanks guys for the help looks like i will have to either slow the machine down or upgrade the drives well since money is the issue and i don't have a lot of work for the machine right now slow and steady it is thanks again.

Dennis

Offline Hood

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Re: Motor tunning
« Reply #29 on: October 11, 2011, 02:31:49 PM »
Yes Dugong drives with a 120V PSU would be what your machine needs but obviously if money is tight at least you can use the way it is.
Hood