Power distribution line protection system

摘要

A plurality of switches are arranged in a distributive manner on a distribution line connected to a power distribution substation, and the switches are connected respectively to fault detection relays. Each of the fault detection relays includes a memory circuit for holding a voltage resulting from a ground fault on the distribution line, and the time constants of the memory circuits are set to become greater in an ascending order from the power outlet of the distribution line. Owing to difference in the time constants, there are differences in the holding voltage of the memory circuits resulting from intermittent ground faults which precede a full ground fault. By utilizing the differences of holding voltage, the switch closest to the full ground fault as viewed from the power outlet of the distribution line is the first to open the circuit.