PURPOSE: To prevent the increase in the size of a switching gear by indicating a ground fault occurred on the load side in a power transmitting direction by a power transmitting direction judging circuit and a bidirectional ground fault detecting circuit or by combining a function to indicate right side or left side with respect to a detecting device independently of the power transmitting direction.
CONSTITUTION: This apparatus comprises detectors 1 to 5 for detecting the current and the voltage of a power distribution line E; a bidirectional ground fault detector 10 for locating a ground fault point at the left side or right side of the detector based on the detection signal from the detectors 1 to 5; power transmitting direction judging means 11 for judging the power transmitting direction based on the signals from the detectors 1 to 5; and an indicating means 12 for indicating the ground fault point on the left side or right side of the detector or indicating the load side of the detector relative to the power transmitting direction based on the detection signals from the bidirectional ground fault detector 10 and power transmitting direction judging means 1. By this configuration whether the ground fault is on the right side or left side of the detectors 1 to 5 is indicated, or the load side of the detector relative to the power transmitting direction can be selectively indicated.
KUMAGAI KATSUHIDE
IKEDO MASAMI
