VFD CONTROLLED MOTORS WITH GFCI

WEMRJRW91

WEMRJRW91

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Location
Sanford NC
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Electric Motor Tech
I have 2 motors that are 20hp pump motors that are controlled on VFDs 460v. Now with the NEC you have to have a GFCI on the units and I have a Southwire HD-PRO 24646. These two unit are fighting one another causing the VFDs to trip out on low voltage. Has anyone ever ran into this problem and what where the solution to solving this problem? Thanks


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There is nothing in a Class C GFCI that would reduce the voltage to the VFD. Going to need a lot more details as to the installation and exactly what is happening.
 
don_resqcapt19 said:
There is nothing in a Class C GFCI that would reduce the voltage to the VFD. Going to need a lot more details as to the installation and exactly what is happening.
Click to expand...

The SPGFCI isn’t allowing the VFD to start up. When powering up the motor it gets to 5hz and then trips out under a low voltage failure. The SPCGFI is currently installed in front of the drive. If installed after the drive the SPGFCI will trip out as soon as you hit start on the drive. The drive that I have installed also has a GFCI internally but isn’t rated for personal use.


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jim dungar said:
Does the SPGFCI trip?
Click to expand...

It only trips when it’s installed after the VFD my technician tried it before the VFD and it will start to ramp up but trips out at 5 Hz then he uninstalled it and installed it after the drive and it tripped out as soon as he hits start on the VFD


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That does not answer anything ...that is a ground fault protection device and does not reduce the voltage other than to zero when it detects a ground fault.
What is the exact application? Is it on the line side of the VFD?
 
WEMRJRW91 said:
...my technician tried it before the VFD and it will start to ramp up but trips out at 5 Hz....
Click to expand...
You have said it trips and it doesn't trip.

To meet the NEC this needs to be mounted on the line side of the VFD.

Does the VFD ramp up past 5Hz without this GF device?
 
jim dungar said:
You have said it trips and it doesn't trip.

To meet the NEC this needs to be mounted on the line side of the VFD.

Does the VFD ramp up past 5Hz without this GF device?
Click to expand...

Without the SPGFCI it doesn’t trip. The Vfd run perfectly without the GF device and will come up to speed fully 60hz


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don_resqcapt19 said:
That does not answer anything ...that is a ground fault protection device and does not reduce the voltage other than to zero when it detects a ground fault.
What is the exact application? Is it on the line side of the VFD?
Click to expand...

Application is an indoor swimming pool


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WEMRJRW91 said:
Without the SPGFCI it doesn’t trip. The Vfd run perfectly without the GF device and will come up to speed fully 60hz
Click to expand...
Does the SPGFCI trip, when it is on the line side of the VFD.
Does the VFD keep working, except for the ability to ramp past 5Hz. What is providing the ramp up signal.

What does Southwire have to say about this?
 
jim dungar said:
What does Southwire have to say about this?
Click to expand...
Probably have no clue, or determine you are SOL, since none of these are designed for use with VSD's

Unlike RCD's designed for it, xFCI likely needs line filters for use with VSD's, probably a different filter for each model.
 
jim dungar said:
Does the SPGFCI trip, when it is on the line side of the VFD.
Does the VFD keep working, except for the ability to ramp past 5Hz. What is providing the ramp up signal.
Click to expand...

Yes, the OP has not made it clear if the SPGFCI is tripping when on the line side of the VFD, which would require the SPGFCI to be manually reset.

It's conceivable that the SPGFCI is tripping, and then the VFD is storing a low voltage error when the voltage on the bus capacitors ramps down and passes below an acceptable threshold voltage.
 
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