gfci tripped by variable speed drive

[2dye4]

I have a variable speed drive that operates on 120 VAC single phase in order to drive a three phase motor as an output.

However this drive trips GFCI outlets where ever it is plugged in.

PWM changes don't help.

I am contemplating a common mode filter but this seems hard to find in high power ratings. Need 15 Amp capability.

Also considering an isolation transformer.

Any other ideas or comments ??

Thanks

 

[VEBill]

It trips other (distant) GFI outlets?

 

[Skogsgurra]

Either an isolation transformer or a VFD with native sinewave (sinus) output. GFIs with 30 mA is difficult. I can imagine that you are using an even lower trip limit. Then I would say you cannot use a GFI with any PWM inverter if you do not use an isolation transformer. Capacitive current leakage from stator windings to stator iron will trip it. Some drives also have filters built-in. That makes it even worse.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[2dye4]

ve

No it only trips the one it's plugged into.

Skoggs, I think you might be right.

Thanks

 

[itsmoked]

Only rarely, with really small VFDs, can you plug them into a GFI and NOT have them trip. If you look at the manual it will likely state the leakage current. You will see it's probably over 5mA which is the typical GFI trip level.

I have the smallest TECO 1ph input unit here in my living room on piece of furniture. Let me try it in the GFI it will eventually be plugged into.... I need a grounded extension cord... I have a grounded extension cord sitting on the coffee table...

Hey! I'm in luck! It doesn't trip the GFI outlet. I really expected it to.

So, as I mentioned, some will work, especially if they're small enough.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

Hey, Smoked!

Was the motor frame grounded when you tried that?

The most current flows through motor capacitance to ground. But only if motor is grounded. Was it?

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

Yes sir! Well grounded to the earth in the same cord.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[BobM3]

Can high frequency noise in the power lines also trip the GFI?

 

[Skogsgurra]

Good o'l reliable safetyminded Smoked..

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[zappedagain]

Not that it solves 2dye4's problem, this forum might like:

http://www.idea2ic.com/GFI/GFICs.html

Z

 

[2dye4]

Zapped

Awesome page on GFCI history

thanks