Hi to all,
I just want to collect some ideas and expert recommendation to justify which IEC standard to use for the calculation of short circuit currents for FPSO (Floating Production, Storage and Offloading Vessel) power system; IEC60909 or IEC61363?
My experience we use IEC61363 for marine...
I agree with you mate youve got to withdraw that breaker and have to inspect it, better if you can invite pecialist from the manufacturer of switchgear.
at least the upstream didnt fail!
Rbulsara, Through fault is not clearly mentioned ANSI/IEEE STD.242-1986 it only dictates to use the maximum available short circuit currents which is the subtransient currents for cable protected by instantaneous overcurrent relay and medium voltage switchgears. For cable protected by fuses or...
Ok, you need to check the downstream protective device and equipment near the fault point better inspect for misoperation or check the generator protective device settings. The problem maybe lies on malfunction on protective devices near the fault point or the grading/ coordination between...
In MV system like 13.8kv and below, we normally used fused-contactor line-up in the outgoing feeder instead of circuit breakers for economical reason, but this is valid only for resistance grounded system in the secondary of delta-wye incomer transformer. The fuse will protect the feeders from...
I agree with them that this is a grading problem on your system, you need to review again all documentations on relay coordination study. Check also the short circuit study, I mean the basis on how they set the protective relay because in your system you can have different scenario like all...
Let me explain how short circuit current flows on a motor feeder cable. If fault occurs on the beginning of cable termination (Fault 1), the fault current flowing on the cables is the motor contribution which is reduced by the cable impedance. On the otherhand, when the fault occurs on the end...
