Detecting and locating MV failure before it occurs. Experience with live line partial discharge detection on underground paper insulated 11 kV cables in London

Detecting and locating incipient failure in underground cables before electrical faults occur has significant benefits in terms of customer satisfaction and quality of supply statistics particularly for “worst served customers” and investment targeting. Timely location and targeted replacement of specific sections of unsatisfactory circuits enables the effective service life of the whole circuit to be economically extended. As some 98% of the supply interruptions in London arise from cable systems, London Power Networks (LPN) is seeking to develop techniques to eliminate cable faults before they occur. LPN have recently commenced installing live line multi-functional monitoring equipment on 300 higher fault rate feeder circuits. Preliminary results of live line condition monitoring have shown very encouraging results in being able to detect and locate failure before it occurs