GFCI Protection For VFD

[Devin_Palmer]

I am working on an estimate for the installation of a VFD for a fluid transfer pump at a brewery. The ground is constantly being hosed down, and it is a very wet location. The only GFCI breakers I can find trip at 6mA of leak current. I have called the manufacturer, and they have told me that the VFD will trip the GFCI unless it is a 20 mA trip setting. 208V three-phase 1.5HP Pump. What should I do?

 

[don_resqcapt19]

Not sure what you are trying to do.
Why does this pump need ground fault protection?
There are special purpose GFCIs that trip at 20 mA, but are many $$$ and are stand alone devices, and a fault on the output side of the VFD will not trip the SPGFCI or GFCI.
Also GFCIs and SPGFCIs don't work on the load side of the VFD because of the varying voltage.

 

[Devin_Palmer]

Gotcha, it is in a setting where the workers will be in standing water while touching the machine. That was the main reason I was concerned about ground fault protection. Is it really not needed?

 

[ramsy]

Gotcha, it is in a setting where the workers will be in standing water while touching the machine. That was the main reason I was concerned about ground fault protection. Is it really not needed?

GFCI nuisance was replaced with systems described in 210.8(B)(4) Exception #2, even if your equipment was supplied by receptacles outdoors.

Worker's compensation claims for the trip hazard of standing water, is more likely to find Mgmt. liable for lack of drainage, or elevated platforms.

 

[tortuga]

I am working on an estimate for the installation of a VFD for a fluid transfer pump at a brewery. The ground is constantly being hosed down, and it is a very wet location. The only GFCI breakers I can find trip at 6mA of leak current. I have called the manufacturer, and they have told me that the VFD will trip the GFCI unless it is a 20 mA trip setting. 208V three-phase 1.5HP Pump. What should I do?

I'd use a three phase RCD or RCBO;

https://new.abb.com/low-voltage/products/system-pro-m/residual-current-devices

 

[Devin_Palmer]

GFCI nuisance was replaced with systems described in 210.8(B)(4) Exception #2, even if your equipment was supplied by receptacles outdoors.

Worker's compensation claims for the trip hazard of standing water, is more likely to find Mgmt. liable for lack of drainage, or elevated platforms.

Thanks man! I missed that when I glanced through the code.

 

[kwired]

Gotcha, it is in a setting where the workers will be in standing water while touching the machine. That was the main reason I was concerned about ground fault protection. Is it really not needed?

Is there receptacles involved that might trigger portions of 210.8 to require GFCI protection?

Outside of that and totally my thoughts, VFD's are pretty sensitive at detecting ground faults on the output side of the drive and possibly better protection than the typical GFCI devices anyway. The drive is protecting itself from fault current, but inherently is going to limit user exposure to any fault current as well.

A GFCI on input side is not going to detect a ground fault on output side either.

 

[tortuga]

A GFCI on input side is not going to detect a ground fault on output side either.

I feel like I have seen 'ground fault alarm' on a VFD before, you guys know way more about VFD's than me but dont they have some kinda built in magic that detects ground faults on the motor side?

 

[don_resqcapt19]

I feel like I have seen 'ground fault alarm' on a VFD before, you guys know way more about VFD's than me but dont they have some kinda built in magic that detects ground faults on the motor side?

Many do have built in ground fault detection on the output side, however the brand that was commonly used at the plant I did a lot of work at was set at 50% of the rated output of the drive. Not adjustable...you either enabled or disabled the ground fault protection when you set the drive parameters.

 

[kwired]

I feel like I have seen 'ground fault alarm' on a VFD before, you guys know way more about VFD's than me but dont they have some kinda built in magic that detects ground faults on the motor side?

Yes they do, and in most cases if there is a ground fault on the load side circuit, the drive will shut down with "ground fault" for a fault code. If it is a motor you are trying to start, it will trip before the motor even has had any noticeable acceleration as it will pick up this fault at a pretty low voltage level during the starting ramp up.

ETA: introduce sudden low impedance ground fault while running and it possibly can be damaging to the drive.