Reclosing relays

Reclosing relay are applied in distribution circuits, to reclose a circuit breaker, one, two, or three times after the circuit has been tripped by the protective relays. Many a time, the faults on the overhead distribution and transmission systems are of temporary nature and the power can be restored through reclosing. The relay has a timer setting, the first reclosing can be instantaneous or time delay, and one complete cycle may be adjustable between some timing limits such as 15–150 s. The relay can be adjusted to reset after a successful re-closer. On unsuccessful reclosing, the close and trip circuits are locked out and an alarm is sounded. With high-speed reclosing, the circuit breaker closing time is compared with the drop out time of the protective relays that initiate a trip out. The protective relays that tripped the breaker in the first instance must open their contacts before the circuit breaker recloses; otherwise, the breaker will be tripped again even if the fault is cleared. The breaker closing circuit must be pump-free. In modern protective schemes, discrete relays will be rarely used. This feature can be programmed based on the timers and the trip and close logic.