Distribution transformer secondary side ground fault detection system

摘要

PROBLEM TO BE SOLVED: To provide a ground fault detecting system for the secondary side of a distribution transformer, which is capable of identifying an accidental portion when a ground fault accident occurs at the secondary side of the distribution transformer.SOLUTION: A ground fault detecting system for the secondary side of a distribution transformer comprises a ground-fault portion detecting device 10 that judges whether a ground-fault accident at the secondary side of a distribution transformer 1 is a power cable internal accident, an external accident in the distribution transformer side or a load side external accident on the basis of a zero-phase current transformer ZCT that is installed so that a secondary power cable 2 penetrates through the edge of a distribution transformer 1 side of the secondary power cable 2, a first instrument current transformer CT1 that is installed in a ground wire of a surge absorber SA, a secondary instrument current transformer CT2 that is installed in the ground wire of a metal sheath of the secondary power cable 2, a ZCT output current Ithat is input from the zero-phase current transformer ZCT, and a first CT output current Iand a second CT output current Ithat are respectively input from the first instrument current transformer CT1 and the secondary instrument current transformer CT2.