Investigation of Fault Event that Affected by The Current Transformer Position

Fault on substation will disrupt the continuity of power transfer from utility to the customer. One case of this phenomenon was occurred on substation A, which is the source of the backbone transmission for large system. This fault broke the circuit breaker chamber and cause 137MW load outage with 73.1 MWh of energy is not supplied. Also, the fault characteristic showed that it has a same phase angle for the all phases which has never been found in Indonesia. Therefore, it is necessary to perform a study to determine the root cause of this fault and enrich the knowledge about substation fault characteristic. Then, this paper presents the fault analysis through field data analysis, modeling, and simulation. This study found that the cause of in phase current waveform for all three phases is single phase (phase T) to ground fault that is caused by circuit breaker internal failure. Also, the current transformer position relative to the fault point will affect the phase angle of the current wave that recorded by Digital Fault Recorder (DFR).