HIGH-VOLTAGE GROUND FAULT RELAY TESTING CIRCUIT WITH BUILT-IN GROUND FAULT TESTING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To make it possible to execute the same performance test in an annual inspection as one executed by using a protective-relay testing device, while in a daily inspection, to detect, easily in a short time, a damage of a relay caused by a surge of lightning or the like and difficult to find by visual inspection. SOLUTION: In this testing circuit, a testing circuit Kt, Lt of a zero-phase- sequence current transformer 6 for ground fault detection is fed with power by pressing a ground-fault testing push button 1 to measure a zero-phase- sequence current. This enables, in inspection, a high-voltage ground-fault switch 12 and a ground-fault relay 11 to be inspected easily in a short time. When the ground-fault relay is supposed to have been damaged, terminals Va, Vc of a TC withdrawal coil 9 are opened and the push button is used to detect the damage of the ground-fault relay.