PURPOSE: To prevent an incorrect judgment from being generated even in the time of a rain fall by judging a 'partial discharge' when temporal differences between a current pulse and an ultrasonic pulse which are concurrently detected at least twice in succession fall within a time set in advance and judging a 'noise' in the other case by a judging unit.
CONSTITUTION: A current pulse and an ultrasonic pulse are concurrently detected at least twice in succession and a temporal difference between both the pulses is calculated by an arithmetic unit 14 provided in a partial discharge monitor body 13 and stored in a memory 15. When the temporal differences for the two time detections fall within a time set in advance, a 'partial discharge' is judged by a judging unit 16 and, when even one of both does not fall within the time set in advance, a 'noise' is judged. Thus, the cases of the incorrect judgment of signals are reduced and the reliability of a partial discharge monitor can be sharply improved.
TERANISHI TSUNEJI
KOBAYASHI TSUNEO
