GB200876A - Improvements in or relating to protective systems for electric conductors - Google Patents

Abstract

200,876. Reyrolle & Co., Ltd., A., and Biles, R. W. March 22, 1922. Protective arrangements of the Merz-Price type for feeders, generators and transformers employ a divertor relav or contactor connected across the current transformers in the ends or sides so that, on the passage of a straight-through current above a certain value, the sensitiveness of the trip coil of the main circuit-breaker or of the relay which trips it is decreased but at other times the sensitiveness remains unimpaired. By these means the usual want of balance of the balancing transformers is compensated for. As shown in Fig. 1, applied to a single feeder, the balancing transformers D connected to the relays coils C in the usual way through pilot wires E are short-circuited by the coils F of divertor relays. With heavy straight-through currents the divertor relays are closed thereby connecting a shunt resistance G across the relay coils C and reducing their sensitiveness. The arrangement for a three phase feeder is similar, but where the feeder section is connected to an adjacent section through a power transformer the divertor relay acting in conjunction with the operating relay of one phase conductor is energized from the current transformer of another phase conductor. The invention is shown in Fig. 5 applied to a fan conductor system in which one phase is split into two parallel conductors A<5>, A<6> which are connected to the opposed primaries of transformers J at each end the secondaries of these transformers energizing relays C<2> which control the tripping circuits. Two balancing transformers J<1> are employed each having four windings opposing one another in pairs. According to the invention as applied to this arrangement each of the coils C<2> is shunted by a resistance G<2> introduced by a divertor relay F<2> energized by a secondary winding on the adjacent transformer J<1>.