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Author Topic: My spindle keeps shutting off randomly.  (Read 4866 times)

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My spindle keeps shutting off randomly.
« 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
Re: My spindle keeps shutting off randomly.
« Reply #1 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. 
Re: My spindle keeps shutting off randomly.
« Reply #2 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?
Re: My spindle keeps shutting off randomly.
« Reply #3 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.   
Re: My spindle keeps shutting off randomly.
« Reply #4 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.
« Last Edit: February 08, 2015, 09:32:45 PM by geh7552 »
Re: My spindle keeps shutting off randomly.
« Reply #5 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
Re: My spindle keeps shutting off randomly.
« Reply #6 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?
Re: My spindle keeps shutting off randomly.
« Reply #7 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.
Re: My spindle keeps shutting off randomly.
« Reply #8 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?
Re: My spindle keeps shutting off randomly.
« Reply #9 on: February 09, 2015, 02:42:37 PM »
Wires before and after breaker feel ambient