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Circuit Breaker Coordiantion

Circuit Breaker Coordiantion

Circuit Breaker Coordiantion

(OP)
I am coordinating some awesome IAC53B relays.  I have attached the graphs.  My question is are these coordinated, and at what levels?  I know circuit 1 instantaneous will open up above 3200 amps, but if I have a fault greater than 10152 Amps that my main relay is set to, both units will operate?

So I am coordianted as long as the fault is below 10,152 amps in the instantaneous portion?

RE: Circuit Breaker Coordiantion

Yep, they'll both operate for a fault on CKT #1 or CKT #2 that exceeds the instantaneous value of the main.

RE: Circuit Breaker Coordiantion

Yes, both operate above 10152A. Typically, you make the curve of the main turn dirctly right a few cycles from instaneous so that the branch circuits first have an opportunity to clear. In other words, the main doesn't have a true instantaneous trip but rather a short delay before any trip.
  

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