PARTIAL DISCHARGE DETECTOR FOR SWITCHGEAR

PURPOSE:To detect partial discharge by arranging first and second conductive parts on the surface and at the end part of a cable joint, while separating each other, and producing a differential voltage between them upon occurrence of partial discharge. CONSTITUTION:An insulating part 4c is arranged in band shape between a conductive layer 4a and a metallic cover 5a on the surface of a cable joint 4 in order to insulate them. Upon occurrence of partial discharge in a discharge gap (d), formed in an insulator on the side of a switchgear by voids and the like, a local voltage variation V takes place in the vicinity of the partial discharge. The voltage variation V propagates in the form of a pulse wave through the switchgear and the cable 5 with a speed close to the speed of light thus producing a differential voltage V0 between the conductive layer 4a and the metallic cover 5a at the opposite ends of the insulating part 4c. The differential voltage V0 is then detected at a partial discharge detecting circuit section.