INSPECTION METHOD FOR AUXILIARY ISOLATOR OPEN/CLOSE SITUATION AND INSPECTION APPARATUS

PROBLEM TO BE SOLVED: To accurately inspect whether the open/close situation of an auxiliary isolator is appropriate when performing distribution line overlapping operation, or the like so that a three-phase AC power supply is supplied from the other set of distribution lines when inspecting an isolator for distribution lines in one set of two sets of distribution lines. SOLUTION: A first distribution line 10a and a second one 10b where single-unit isolators 11a, 11b for distribution lines are withdrawn from the three-phase AC power supply 1 are connected in a loop at the normally open-circuited auxiliary isolator 20; the presence or absence of a zero-phase current in a three-phase line N between isolators of the first and second distribution lines 10a, 10b and the auxiliary isolator is detected by a zero-phase current transformer 50 after performing throw-in operation so that the auxiliary isolator 20 is closed-circuited; and it is determined that the throw-in of the auxiliary isolator 20 is incomplete by the detection of the presence of a zero-phase current; the distribution line overlapping work is suspended, and inspection stop of the isolator is instructed. When canceling the distribution line overlapping, incompletion of opening of the auxiliary isolator is determined by the detection of the presence of a zero-phase current. COPYRIGHT: (C)2010,JPO&INPIT