DETECTION SYSTEM FOR SECONDARY-SIDE GROUND FAULT OF DISTRIBUTION TRANSFORMER

摘要

PROBLEM TO BE SOLVED: To provide a detection system for secondary-side ground fault of distribution transformer, which is capable of identifying a point of ground fault that occurs on a secondary side of a distribution transformer.SOLUTION: A ground fault point detector 10 determines which one of an inner accident of a power cable, an external accident on a distribution transformer side and an external accident on a load side leads to a ground fault, by obtaining, on the basis of a phase of zero-phase voltage Vinput from a zero-phase voltage detector ZPD that is provided between a distribution transformer 1 and a secondary power cable 2, directions of: a ZCT output current Iinput from a zero-phase current transformer ZCT that is provided at an end part of the secondary power cable 2 on the side of the distribution transformer 1 so that the secondary power cable 2 penetrates; a first CT output current Iinput from a first instrument current transformer CT1 that is installed at a ground line of the zero-phase voltage detector ZPD; and a second CT output current Iinput from a second instrument current transformer CT2 that is installed at a metal-sheathed ground line of the secondary power cable 2.