Powerflex 525 F013 Ground Fault

[LGSF 0]

Hi

We are getting a Ground Fault error F013 consistently (9 times out of 10) when we try to run one of our rolling mills in auto mode.

We do not get the issue when we jog forwards in manual.

This is a machine that we refurbished with this new drive and a new Nord motor.

We have megged the motor and it is good. We have checked the supply cable between the vfd and the motor and that is fine.

We have tested the setup with supply cable earth in 3 states, earthed both ends, earthed motor end only and completely unearthed.

Obviously this was purely for fault tracing and not intended for permanent state.

The fault remains.

The firmware is 5.001 I believe.

There is an end encoder on the end of armature and 24v case fan fitted to the motor.

We have a twin machine that was refurbished at the same time and that is working fine, only difference is an SEW motor of the the same size.
Our plan is to pull the known good drive and temporarily trying it, without auto tuning so we can reinstate the working mill.

Does anyone have any thoughts on further checks or a solution please?

 

Many thanks in advance

 

Edited 23 Jun 2021 by LGSF
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[pturmel 157]

A difference between manual vs. auto behavior suggests the fault is on the control wiring side, not the power wiring.  Only suggests, though--it could be a motor cable shield problem that is inducing voltage in your ground plane, where the effect is only detectable at normal (auto) power levels.

[LGSF 0]

Thanks for your response 

We are currently checking all wiring 

Have tried running vfd with a different motor and cable, also tried with motor disconnected 

Same fault F013

Seems to be pointing towards being a faulty drive…

The shame is that we refurbished this machine prior to lockdown but never commissioned it and it’s never turned a wheel until we need it now 18 months later. Probably out of warranty…

 

Also updated firmware from 5.001 to 7.001 but still no improvement 

[BobLfoot 301]

jog speed is usually slower than running speed unless you "tweak" it up.

is your jog speed equal to run speed?

[VFD Guy 13]

Many things can cause this. I’ll start with some basic questions. Are you in vector mode? What v did you megger at? If you fault with no motor connected, meaning disconnected at the output terminals of the drive, it’s likely a bad VFD. Ground fault basically means a current imbalance and the drive assumes it’s going to ground. Start the drive with no motor leads in v/hz mode and measure output v. If balanced V then the drive may be ok but if unbalanced, the drive is for sure bad

[LGSF 0]

5 hours ago, BobLfoot said:

jog speed is usually slower than running speed unless you "tweak" it up.

is your jog speed equal to run speed?

Jog is around 15% of max line speed

[LGSF 0]

3 hours ago, VFD Guy said:

Many things can cause this. I’ll start with some basic questions. Are you in vector mode? What v did you megger at? If you fault with no motor connected, meaning disconnected at the output terminals of the drive, it’s likely a bad VFD. Ground fault basically means a current imbalance and the drive assumes it’s going to ground. Start the drive with no motor leads in v/hz mode and measure output v. If balanced V then the drive may be ok but if unbalanced, the drive is for sure bad

Yes we are in vector mode

Meggered at 1000v

 Disconnected at vfd output terminal 

Tested with another motor and lead following my last post with same original results 

I have a spare drive that I’m going to swap across now and try

 

Thanks all for your input so far

[VFD Guy 13]

Does it occur in V/Hz mode? does this occur in Vector mode with the encoder set to open loop?

[LGSF 0]

We seem to have a fix for the installation.

I swapped to a spare drive of the same type and still got the ground fault on run command.

There was 0 for parameter 41 - (Accel Time 1) which was the same as the other rolling mill with the same PF525 drive which has no problems, this was setup and commissioned by a subcontractor.

I changed it to 10ms and now the initial instant current draw appears to be been ignored and the mill has run in a stable condition for a short but reasonable production run this afternoon.

Whether this is a correct resolution to the issue is yet to be seen, and I’m not a vfd expert in any way, but I’m not convinced the F013 ground fault was a true fault diagnosis given by the PF525 fault code.

 

[VFD Guy 13]

Sounds good. Having a ramp time of 0 is not really a good idea anyway. Glad to hear you’ve resolved it

[Boxyau 0]

I have a couple of PF525 fw7.001. They were running OK but the customer required me to turn on Output phase loss En (A557). With this turned on, I get F013 -Ground Fault whenever I try to run the motor.  I tried adjusting Phase Loss Level (A576), but this didn't help.  When I turn A557 back off, the motor runs fine again. Has anyone had this problem before? Does anyone know why A557 has an effect on ground fault detection?