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Mach Discussion => General Mach Discussion => Topic started by: jonny quest on February 08, 2015, 03:37:02 PM

Title: My spindle keeps shutting off randomly.
Post by: jonny quest on February 08, 2015, 03:37:02 PM
Running a ethernet SS, no rhyme or reason spindle will randomly shut off. VFD shows error of low voltage control.

Are there debounce settings in SS config... or any changes I can try in config to help?

When the issue is so random it's hard to trouble shoot
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 08, 2015, 08:36:54 PM
VFD Low voltage error message is usually due to low incoming line voltage and has nothing to do with debounce or Smooth Stepper. If this is a Chinese VFD chances are it's about to die and has nothing to do with low line voltage. 
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 08, 2015, 08:53:34 PM
This is a Teco FM50 VFD. And I just replaced VFD with this one because the original VFD was doing same thing... so it's definitely not VFD.

I tried to monitor incoming voltage but it's hard because this problem is very random. 

Is there a procedure to check in coming line voltage?
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 08, 2015, 09:16:44 PM
You would need to use a voltmeter and monitor the line voltage and try to catch it. Higher quality meters like Fluke have a min-max function that locks in voltage swings.

Teco and most if not all VFD's monitor the internal DC bus voltage. The VFD converts incoming AC to DC and then back to AC to the motor. If the DC voltage drops below a preset level it will shut off the drive. If the incoming line voltage is stable and still getting the low voltage errors then it is the drive. It could also be the circuitry that monitors the voltage is defective.

The line voltage would have to be low for at least 3-5 seconds to trip a VFD because the dc section has capacitors that have to discharge to a point to trip a low voltage error. Industrial VFD's have a "Ride Through" setting that helps prevent low voltage tripping.   
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 08, 2015, 09:28:15 PM
Just checked the Teco specs. Momentary power lose is 2 seconds and DC voltage less than 200V for the 120/220V single phase drive.  Try connecting up a light bulb to the line power and see if it dims at the same time the drive trips.
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 09, 2015, 12:03:41 AM
I just checked the line in voltage.  It varies from 213 to 215 ac. It doesn't fluctuate when spindle mysteriously shuts off.

I'll have to try and figure out how to measure the 200v dc you mentioned above
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 09, 2015, 12:27:01 AM
I also just hooked voltmeter to the V and W directly at spindle motor.  The spindle started all by itself even though Mach3 reset button was still flashing!

Why did that happen?
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 09, 2015, 09:30:17 AM
Even though Teco specs say 200-220V line input +/- 10-15%.  213-215 vac on the line side maybe marginal could be the reason for the random low voltage errors even though the mfg specs say different. Measuring the voltage are the motor won't be of much use... it will vary depending on motor speed. 

Not sure why the drive would start on its own. I would isolate the VFD from Mach (use the drive start/stop and speed control) and see if the problem happens.
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 09, 2015, 02:41:16 PM
Ok... finally getting somewhere!

My machine is a IHCNC turnkey (using their term loosely)

I called Factory Automation. .. great people by the way!  My VFD was hooked up to L1 and L2 from factory.... L1 and L3 is what it is supposed to be.

It seems to work!  But.... it uses a 20 amp breaker for control cabinet on off switch. At full RPM no load that breaker will trip after 10 minutes of running. Breaker is getting warm... not hot... should I just replace breaker... or do I have bigger problems?
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 09, 2015, 02:42:37 PM
Wires before and after breaker feel ambient
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 09, 2015, 05:27:43 PM
First, circuit breakers should never be used as a switch unless they are rated for switching. If the breaker is switch duty rated it will be marked "SWR", "SDR" or "SW". This also stated in the Teco manual on page 14. (www.tecowestinghouse.com/Products/Drives/fm50.html)

Second, someone at Factory Automation better read the user manual. According to the Teco FM50 manual single phase power HAS to be connected to L1 (R) & L2 (S), NOT L1 & L3.

The breaker is getting warm and tripping when connected the L1 & L3 because L3 is using a part of the internal power circuit reserved for 3 phase power. The breaker is doing it's job and protecting a miswire power connection. Changing the breaker will NOT fix the problem. Almost all single phase VFD's I've worked with ALL use L1 & L2 and Teco is no different.

Either you have a incoming power problem or a defective VFD. Seeing you changed the VFD once already and still have the exact same problem, then it points to the 213-215VAC power, which is low for a 220-240VAC circuit.
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 09, 2015, 05:32:12 PM
Dang it! I thought I was getting somewhere!  Back to square one... should I just buy a buck booster and try that?
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 09, 2015, 07:50:33 PM
I need some details... is your cnc in a home or business? What size is the VFD and the motor?

Power companies supply 220v-240v power to residential homes. 213Vac is pretty low unless you are located on the fringes of the utility grid. Low voltage can cause problems with air conditioners, refrigs, etc. You can contact the local utility company and have them check the line.      
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 09, 2015, 08:10:36 PM
I rent a space in an industrial building.  I'm only using 2phase... but I believe building is 3phase.

3hp motor, FM150-203C. Ac 1phase 200-240v 50/60hz 27/16a
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 09, 2015, 08:40:30 PM
Ok... a totally different set of conditions here. Industrial 3 phase is usually 480V, 3 phase then stepping down via transformers to 277/208V single phase as needed for CB panels etc. Willing to bet you have 208V so the measured 213-215V is ok. Between 1 phase (L1) and neutral you have 120V and the other phase (L2) and neutral 120V, and between both (L1-L2) phases 208V or in your case 213V. It won't be 120+120=240V.... that's a whole other story as to why.

Getting a VFD low voltage fault is really an indicator of a incoming power problem. Especially after changing the drive and having same problem. It's possible on of the phases is dropping out or going low just enough to trip the drive. Have a qualified electrician check the circuit breaker panel specifically for lose connections or burned connections where the breaker attaches to the panel bus bar. Its possible to have a normal voltage reading without a load on a burned or lose 2 phase breaker then the voltage drops under a load. Or move the wires to another breaker.

This is a long shot... It could also be someone in another part of the building is starting a piece of equipment causing the the power to dip long enough cause problems.

Let me know how you make out.

 
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 10, 2015, 07:29:00 PM
Electrician came out checked the breaker panel.  All good in there.

Next step is to call local service. .. but even he said. .. i really won't get anywhere with them. They all have a range of where is considered in the range.

I'll buy a buck booster if it's worth a shot. I can't use machine and need to try things.

Do you think it's worth a shot to try buck booster?
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 10, 2015, 09:36:00 PM
You can try a buck boost transformer. What bothers me is the drive specs for Teco fm50, single phase, 3hp is 200VAC - 240VAC so it should work at 213-215VAC. This is the second drive with the exact same problem. Getting two bad drives is a million to one chance. Everything the drive "LV" fault message is pointing to a line power issue.

L1 & L2 only should be connected to the line power for single phase. Did the electrician take a voltage reading with the drive in run mode?

Ok... this maybe a dumb question but are you sure it's not a 460V drive?

 
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 10, 2015, 10:46:26 PM
Not 460.

No electrician did not. 

I'll do that tomorrow.  That's AC voltage at L1 L2? What should it be?
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 10, 2015, 10:46:54 PM
And the other drive was not a Teco
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 11, 2015, 08:45:13 AM
Measure the voltage at the drive terminals L1 &L2 with the drive off then measure again with the drive running and compare the readings. Should be the same with no voltage drop. If you have a 208V system it should be 208V or a little higher. If it's a 240V system it should be around 240V. In any case it shouldn't be less than 200VAC.

The electrician should have tested the voltage... that's pretty basic troubleshooting. I'm running out of ideas.... it's difficult to problem solve without actually seeing the problem.
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 11, 2015, 01:04:23 PM
On the phone with Teco right now.  They keep telling me L1 and L3 is the correct terminals to use
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 11, 2015, 04:37:07 PM
Teco's FM50 user manual clear shows L1 &L2 for single phase 200V - 240V. Ask Teco why the breaker gets hot and trips when using L1 & L3. I'm curious for their answer. 
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 11, 2015, 08:03:00 PM
At the risk of jinxing myself,  I think I found the problem.

I replaced the on-off switch/20 amp breaker.  When I took it off, it definitely looked suspect.  This is big what if though.  Did it get hot and damaged from running on L1L3.... or?

I'm currently on L1L2. That's the way machine was set up.

Just for clarification, Teco model FM50 203. I wonder why they were so insistent on L1L3?
Title: Re: My spindle keeps shutting off randomly.
Post by: geh7552 on February 12, 2015, 09:26:44 AM
I have no idea why you were told to use L1 & L3. Teco (Westinghouse), Toshiba G3, G4, Automation Direct and almost all single phase VFD's including the cheap Chinese junk VFD's are electrical the same use L1 & L2.  I have a Automation Direct GS-2, 2hp, 240V drive wired to L1 & L2... runs great.  I don't think the drive is damaged unless it faults out on "OC" when powering it up. If you get a "OC".... the drive's power section has failed.  

Again... NEVER use a circuit breaker as a on/off switch unless it's rated for switching. If it is, it will be marked "SDR", "SWR" or "SW" on the case. Buy a separate 2 pole power switch instead which is allot cheaper than replacing a 2 pole 20A or 30A breaker.

One thing to consider is the incoming power wire size and distance from the circuit breaker panel... a 3hp motor and VFD, 200V-240V should have no less than #12 AWG with #10 AWG being the preferred to prevent voltage drop and overheating the conductors.    

Let me know how you make out.
Title: Re: My spindle keeps shutting off randomly.
Post by: jonny quest on February 13, 2015, 08:48:18 PM
Ran it for a couple hours today with no issues. Thanks for your help!