Development of A Portable Instrument for Detecting Partial Discharge by Ultrasonic Beamforming Technique

In this paper, we introduce partial discharge visualization technology. To monitor partial (external corona or creeping) discharge at exposed parts remotely, detection of ultrasound emitted from partial discharge is frequently carried out. Beamforming technique, in which ultrasonic waves measured by multiple microphones are analyzed, was adapted for determining an arrival direction of ultrasound. By superimposing arrival direction of ultrasound on video image of an objective apparatus recorded by a camera, we can promptly know position where partial discharge occurs in wide area to be monitored. A small and lightweight instrument called “Corona Discharge Viewer™ MK-760” was developed for on-site partial discharge detection. The beamforming computing is carried out repeatedly in real-time, and location of partial discharge is shown with visual image on the LCD display. Therefore, we can easily detect and locate partial discharge by just moving MK-760 facing towards to objective apparatus without any esoteric operations. Corona discharge occurred at an insulator and a bend section of a twisted bare wire of actual electric transmission facilities were satisfactorily detected and located by using MK-760.