ratio-differential relay

例句：

1. 1. The ratio-differential relay is used to detectthe flow of electrical current in a circuit.
   比例差继电器用于检测电路中电流的流动。
2. 2. The ratio-differential relay wasdesigned to improve the accuracy of power measurement.
   比例差继电器被设计用来提高电力测量的准确性。
3. 3. The ratio-differential relay isan essential component of a power system's protection system.
   比例差继电器是电力系统保护系统的必备组件。