Improving electric railway fault clearing times

THE CIRCUIT BREAKERS designed in 1913 for sectionalizing the 11/22-kv 3-wire trolley and feeder circuits on the New Haven Railroad electrification had become inadequate by 1936 because of limited interrupting capacity to clear line faults fast enough to insure system stability and reliability. Although these never were designed to handle the entire fault interruption duty, space and weight limitations in the switching stations and supporting structures ruled out their replacement with modern circuit breakers of conventional design for faster fault clearing by line circuit breakers directly. The oil circuit breakers are known as “bridge-type” circuit breakers because of their location on the anchor bridges spanning the railroad tracks and catenary contact system. Figure 1, of a typical switching station, clearly indicates the space and weight limitations involved because of the location of the circuit breakers on the anchor bridges.