Standard Class A 115V~ GFCI (Ground-Fault Circuit Interrupters) are designed to 
TRIP at currents around 6mA. I assume this current is accurately detected 
between DC  and some harmonic of 60hz.  However, it is common knowledge that 
GFCIs can false trip or nuisance trip when used with motor speed controllers, 
lighting dimmer switches, frequency drives, etc. .

I'm not familiar with UL 943C. Does this standard call out specific immunity 
levels, energy and frequency, that GFCI must properly operate at?  Are there 
published Trip Curves that shows current vs frequency?

Has anyone run across published data showing high frequency trip 
characteristics of GFCIs?

We have been burned in the past with nuisance tripping GFCIs when products with 
frequency drives ramp start a motor. We are trying to understand exactly what 
is causing the GFCI to trip so we can design out the problem in future 
products. Any insight, recommendations, or suggestions would be most 
appreciated.

Best regards,
The Other Brian
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