Setting delay time for ground fault protection

[Magic Gorge]

When determining the circuit breaker ground fault settings for two or more tiers, should there be any consideration for the time gap between the delay settings? For instance, if I set my main at 0.4 seconds and feeder at 0.3 seconds, the curve sheet shows no overlapping. However, should the feeder be set lower to avoid nuisance tripping?

 

[iceworm]

When determining the circuit breaker ground fault settings for two or more tiers, should there be any consideration for the time gap between the delay settings? For instance, if I set my main at 0.4 seconds and feeder at 0.3 seconds, the curve sheet shows no overlapping. However, should the feeder be set lower to avoid nuisance tripping?

Check the tolerances on the devices. Make sure an overlap didn't creep up on you. Otherwise, 'Coordination' is defined as, 'Daylight between the curves'.

ice

 

[Magic Gorge]

Okay thanks, the tolerance bands seem to conform with the published info I could find.