The 300 amps is on all phases and is steady, the only variance is load related on the MCC. It can start at 285 amps when the secondary brkr is closed and progress form there until it reaches the over current trip setting.
The CT ratio is identical on both XFR’s and both have been on line since...
It is a new installation but has been on line and working per designed for about 5 months now. This problem just started last night and yes your assumption is correct the tie brkr is definitely open when we close the secondary side brkr
We have two 6KV XFR that feed two individual 380V MCCs with an ATS that closes the Tie brkr between them whenever one of the XFR feeders fail. Last night one of the XFR feeders tripped on over current and we found the XFR that tripped is pulling five times (300amps) on the primary side then the...
