Coordination Question
Coordination Question
(OP)
Hello,
I have been reviewing a coordination study done in-house at corporate level. I am in the plant. There appears to be some lack of coordination with the utility fuse, main breaker (2000A) and feeder breakers (600A). I am being told that the reason is breakers are large in relation to utility transformer 750kVA. Apparently, there is no way to improve coordination unless either feeder breakers are smaller or utility transformer is larger. Is this correct? Looking for independent viewpoints as I have to live with this at my plant. The TCC is attached (I hope)
Thank You
I have been reviewing a coordination study done in-house at corporate level. I am in the plant. There appears to be some lack of coordination with the utility fuse, main breaker (2000A) and feeder breakers (600A). I am being told that the reason is breakers are large in relation to utility transformer 750kVA. Apparently, there is no way to improve coordination unless either feeder breakers are smaller or utility transformer is larger. Is this correct? Looking for independent viewpoints as I have to live with this at my plant. The TCC is attached (I hope)
Thank You






RE: Coordination Question
RE: Coordination Question
RE: Coordination Question
RE: Coordination Question
Other than that, I agree with dpc, you might need to sacrifice coordination between the fuse and the main breaker.
RE: Coordination Question
I agree with others on adjusting the main breaker trip settings to the right; say Inst pu = 8000A, stpu = 5,500A.
RE: Coordination Question
RE: Coordination Question
Sliding the main tripping characterisc over does reduce the chance of nuisance trips on temporary overloads.
Check the impact on the arcflash levels at the switchboard before changing the main breaker settings. Increasing the trip time might increase the exposure.