Development of AC Feeding Circuit Load Zone Measuring Device(R-X Analyzer)


Y.MOCHINAGA, Y.HISAMIZU, K.AJIKI


In AC electric railway, when a fault happens to the feeding circuit, the protective relay detects the fault and the circuit breaker acts to cut the fault current. Distance relay is one of such protective relays, which monitors the impedance of the feeding circuit and acts to eliminate the impedance if it comes into the block diagram. In determining the protective zone of the distance relay, it is important to investigate the state fo the loading and take coordination measure to avoid needless action of the relay. Then, a specific recorder has been developed using a microprocessor. It can continuously calculate the load impedance from the substation voltage and current and register the calculated results collectively on an imapedance plane composed R (resistance) and X (reactance). Being installed at a substation of AC feeding circuit, the recorder contributes to appropriate setting of the distance relay.