My QO-GFI breaker is nuisance tripping, even though the ground fault leakage current is under 4ma. There is a high frequency component. Is there a fix?
Will QO-GFI and HOM-GFI breakers work on a load that generates a high frequency (such as a VFD), or will the high frequently cause the GFI to nuisance trip?
QO-GFI and HOM-GFI breakers
QO-GFI and HOM-GFI circuit breakers are rated to be used on 60Hz systems only, and are designed to trip when a 60Hz ground fault current between 4ma and 6ma is detected.
Even when used on 60Hz systems, some types of loads (e.g. VFD) can generate a high frequency ground fault current. That high frequency ground fault current can be additive and may increase the sensitivity of the GFI breaker, causing the GFI breaker to nuisance trip as a result of the high frequency ground fault current being present. To reduce the effect of the high frequency, in 1999 a "high frequency roll off" circuit was added to GFI breakers. GFI breakers with the roll off circuit are less likely to nuisance trip when there is high frequency.
If you have pre-1999 GFI breakers feeding loads that generate high frequency ground fault current, and those breakers are nuisance tripping, consider replacing them with newer GFI breakers (which have the high frequency roll off circuit).