抄録
This paper describes the development of Automatic Fault Point Locating and Sectional Isolating System. This system locates a single-line-to-ground fault point at each pole by using ground-current-sensors and isolates the faulted section by controlling pole switches with no outage of unfaulted sections.
The ground-current-sensor is connected to the line between allied earth terminals of pole devices and grounded conductor. It detects a ground fault current of more than 0.64 amperes that is determined so as to avoid an unexpected operation by stray-current but to detect the fault current certainly and sends out a emergency signal with time delay of 0.1 seconds.
Sectional isolation starts when both the emergency signal from the sensor and relay operation signals from substation are received and ends within a feeder circuit breaker's tripping time of 1.5 seconds.
