Last week, we upgraded the rating plug and the trip unit with a 300A one and this resolved the issue. Luckily, I didn't have to upgrade the cable sizes. It's interesting that on the coordination study, the inrush current was not in the tripping zone of the 225A unit, but it did have this...
The CB is 400AF/225AT (sorry for saying 250AF in the beginning...that was what specified on single-line. The furnished CB is 400AF).
The plug rating is adjustible for Short-Time Pickup and Short-Time Delay. The time delay can be either LS (if set to 100, 200 or 300ms) or LI (if set to...
@jraef:
Thanks for the reply. As for the XFMR inrush current, I myself was really suspicious that this is most likely the root cause. However, after I verified the coordination study, the inrush current is not in the tripping zone of that CB. (see attached TCC - The breaker with the nuisance...
Description: We have just recently installed a 480V, 560kW/700kVA diesel generator as an optional standby backup power for an existing building (single-line shown in the link below). The generator has a built-in 800A main CB, feeding a new Generator Dist. Board (main lug only). Three outgoing...
