Automatic Reclosing High-Speed Circuit Breaker Feeder Equipment for D-C. Railway Service

High-speed circuit breakers have been used in both feeder and machine circuits of railway substations. It is the purpose of this paper to point out some of the advantages gained by placing this type of breaker in the feeder circuit and also to describe some of the more common types of feeder equipment using a well known form of high-speed circuit breaker. A brief summary of the breaker characteristics is given, together with the results of short circuit tests made on 600-volt reclosing feeders employing this type of breaker. The reclosing action is ordinarily obtained by means of a relay which, in conjunction with a load indicating resistor, measures the resistance of the external circuit. The action of this relay is purposely delayed, after the opening of the breaker, in order to permit feeder conditions to reach a stable value and particularly to enable all transient and counter e. m. f. effects to disappear before the reclosing devices are given control. The latter effects usually disappear within a few seconds of opening the breaker on the usual type of railway circuits. In a majority of cases a time delay of 10 to 30 seconds (after the opening of the breaker) elapses before the reclosing devices are given the control of the breaker. After this time delay has expired and load conditions have reached the desired value the circuit breaker is reclosed.