MCCB TRIP FUNCTIONS

All of the above settings are based on sensor size of circuit breaker, and will be set according to the cable size or load..

Ex: Breaker is a 500 amp frame with 500Amp sensor / CT

Short Time Setting is .8 so .8X500= 400 amps so at 400 amps the trip unit will start timing, and depending time delay setting will give you actual time the breaker will trip of which will be very short. (Usually set to max cable size / breaker normal current rating)

Long Time setting is .7 so .7X400= 280 amps so at 280 amps the trip unit will start timing, but will take a very long time to operate, and is also curve dependent of which will be in multiples of pickup (pickup=280amps) ..(Curves will be found in circuit breaker documentation) (Usually set to match load)

Inst setting is set to 6XIR, and IR=280.. 6X280= 1680Amps.. The breaker will trip instantaneously at 1680A (Take care not to exceed circuit breaker interrupting capacity)

Ground Fault is used to detect if any of the three phase conductors go to ground, of which will normally be set fairly low.

In my previous post please disregard the comments concerning (usually set to max cable size / breaker normal current rating) & (usually set to match load)..

The trip units need to be set below damage curves of cables and equipment you are feeding...

Thank you very much ekiechle!