Protection of Electric Locomotives and Cars to Operate with High-Speed Circuit Breakers

This paper discusses the requirements for protecting the high-tension circuits of an electric car or locomotive which operates on the a-c. single-phase system of electrification. The means which must be employed to secure this protection is outlined. The types of relays used by the Pennsylvania Railroad for this purpose are described, together with the connected control circuits. These relays are known as pantograph lowering relays, and they make use of the opening of the substation breakers on a short circuit to disconnect the electrical equipment of the car or locomotive from the line by lowering the pantograph. Tests of high-speed relays recently developed indicate that these relays will give satisfactory service with high-speed circutit breakers in the trolley feeders at the substations. In conclusion, results justify the elimination of circuit breakers from electric cars and locomotives by the substitution of the pantograph lowering relay.