Acousto-Optic Combined Detection Technique for Partial Discharge Defect of Earthing Switch

This paper introduces the detection and analysis for an abnormal corona defect of a 500kV B-class earthing switch using combined detection technique of ultraviolet imaging and non-contact ultrasonic. Combined with ultraviolet detection spectrum, ultrasonic partial discharge spectrum and equipment inspection results of corona defect location, the principle of arc extinguishing system and failure reason is analyzed. The fault is due to poor contact between drain line of arc extinguishing chamber and main contact conductor, which causes Continuous induction discharge around the contact area with earthing switch in open position. Due to early detection and timely treatment of this defect, possible loss is avoided.