# Powerflex 525 Drive Issues F003/005



## gpop (May 14, 2018)

If possible un-wire the drive then do a diode test following the instructions on Allen Bradley web site (make a account its free)

If you can not shut it down take a amp reading of A-B-C.

Once the f003 fault is diagnosed there are lots of ways to fix F005


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## JRaef (Mar 23, 2009)

The way all A-B drives detect a "phase loss" is actually by monitoring the DC bus voltage _ripple_, there is nothing looking at the actual incoming line voltage. So in this case since you have eliminated the possibility of fluctuations in the line, it might be related to resonance with other capacitors on the same line. Not caps on the DC side of rectifiers, but things like Power Factor Correction capacitors or starting of large single phase motors, old fashioned battery chargers etc., usually on the same line source. If that's not it, it might be indicative of the drive DC bus capacitors starting to fail or there being a loose connection on them.


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## oliquir (Jan 13, 2011)

how old is the vfd? Has it been used 24/24h everyday?


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## GatorIE (Mar 22, 2020)

JRaef said:


> The way all A-B drives detect a "phase loss" is actually by monitoring the DC bus voltage _ripple_, there is nothing looking at the actual incoming line voltage. So in this case since you have eliminated the possibility of fluctuations in the line, it might be related to resonance with other capacitors on the same line. Not caps on the DC side of rectifiers, but things like Power Factor Correction capacitors or starting of large single phase motors, old fashioned battery chargers etc., usually on the same line source. If that's not it, it might be indicative of the drive DC bus capacitors starting to fail or there being a loose connection on them.


JRaef, thank you for the suggestion on line resonance. There is an older well pump control fed from the same panel as this drive system. We suspected that this could be the cause of ripples on the line and, sure enough, shutting down that pump system seemingly eliminated the issue. We found that the drive faults coincided with the starting of the well pump motor. Our current plan of action is adding an input line reactor to hopefully minimize line voltage distortion and see if that fixes the issue.


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## JRaef (Mar 23, 2009)

A line reactor may not make a difference in this situation, but it’s a good idea to have one anyway. I’m just setting your expectations. You will likely have to figure out the problem in that older we’ll system that is causing the disturbance. Loose connection there? Motor winding going bad? PFC capacitors? Is it a large single phase motor?


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## gpop (May 14, 2018)

Are the field wires in the same conduit?


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## JRaef (Mar 23, 2009)

gpop said:


> Are the field wires in the same conduit?


Ooooh... good point.


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## paulengr (Oct 8, 2017)

Not mentioned...have you tested the motor? Or the drive? Disconnect motor at the drive. Then test line-to-line with a milliohm meter, then test line to ground with a megger at 60 seconds, 500 V test voltage. If you have a pdMA or a Baker just do that instead, I'm just giving you the common tools you should have if you work on motors and drives.



Milliohm readings should be less than 3%. So add together, divide by 3 and write that number down. Then subtract each of the individual readings from the average. Multiply by 100, divide by the average. Get all 3 numbers. Drop the sign. Take the highest one. So if we have say 10, 11, 12, the average is 11. The unbalance numbers are -9.1%, 0%, and +9.1%. Take 9.1% as the %unbalance. This test looks for shorted turns and/or loose connections.


Megger reading should be at least 5-10 Megaohms minimum. Watch as you get the reading. If it's bouncing all over the place, you got a moisture issue. If it's just low, its either dust or failed ground wall insulation.


Do NOT use a multimeter for either test. It has neither enough current and no Kelvin clamps for the milliohm test, nor enough voltage for the megger test.


If it fails either test, unwire motor and test again at the motor itself (is it coming from the wiring or the motor?) As you unwire it pay close attention in case you are just fighting a problem at the motor connections themselves.


If there are issues with a motor, it will drive VFD's crazy causing all kinds of goofy errors. The faults you mentioned are both pretty common for either connection issues or failing/marginal motor issues. Usually this is just early warnings that the drive is failing.



Along the same lines as JRaef mentioned you can check the DC bus yourself. Don't trust the VFD. Just take your multimeter and carefully put your meter on the "DC+" and "DC-" terminals. Set your meter first to DC and verify that the drive is reading the correct DC bus voltage. Then flip it to AC and check ripple on the DC bus...should not be more than a couple Volts at the most and thats when it's changing speeds. Anything bigger than that and you got serious issues. When you do this test on a lot of drives you need the probe covers in place so only the tips of your multimeter are exposed. This test should do two things. First if you have a bad rectifier you will see DC bus ripple is high. Second is that if the readings are off even a little compared to what the drive reports, you will know that you have a bad sensor system in the drive. If you have an oscilloscope this goes a lot faster and the exact drive issue will be a lot more obvious but again that's a fairly expensive tool not everyone has.


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