The VFD is giving Ground Fault ... What might be the possible reasons ?

[danishdeshmuk]

The VFD is giving Ground Fault ... What might be the possible reasons ?


The VFD is Allen Bradley PowerFlex 400

1) Any Phase inside the terminal of motor is touching with the motor frame or body.
2) An phase inside the connection terminal strip of VFD is touching with metallic frame or metallic body of VFD.
3) Any phase is touching with other phase inside the motor terminal
4) Any phase is touching with other phase inside the VFD terminal connection strip
5) Any phase is touching with earth cable (wire) inside the motor terminal
6) Any of the phase is touching with earth cable (wire) inside the VFD
7) Motor's insulation becomes weak.
8) Motor's winding is touching the frame or body of the motor.
9) Any phase is touching the other metallic part or frame or body in between motor and VFD (somewhere).

Are these above mentioned reasons cause of Ground Fault ?

Are these all those possible reasons which cause the Ground Fault to display on VFD LCD ?

Is there any other possible reason of displaying Ground Fault on VFD display ?

 

[rfredel]

Hello danishdeshmuk,

Nr. 3 and 4 are not possible, because phase to phase is not ground fault, it's short circuit.

All others are possible, but my favorite is Nr. 7

Take a megohmmeter and measure the leakage resistance between groung and every phase.

I hope it helps.

Regards

Rainer

 

[danishdeshmuk]

Hello danishdeshmuk,

Nr. 3 and 4 are not possible, because phase to phase is not ground fault, it's short circuit.

All others are possible, but my favorite is Nr. 7

Take a megohmmeter and measure the leakage resistance between groung and every phase.

I hope it helps.

Regards

Rainer

Can't it be the VFD (VFD circuit) problem ? Like any bad output transistor if motor's meggering is fine

 

[rfredel]

Hello danishdeshmuk,

My cristal ball says, it can be all.

It's very difficult to find the reason from here, without more data. I can only guess, what it is.

Here you can only measure with the megohmmeter.

A bad isolation of the output transistor normaly make short circuit to ground. Can it be, that something is wet and get connection to ground?

Can you, only for testing, connect an other motor or cable. Try to use lamps as load for the VFD and look what happens.

Ask the technical support of the magnufactor.

I hope it helps

Regards

Rainer