Experiences from over 15 years of on-line partial discharge (OLPD) testing of in-service MV and HV cables, switchgear, transformers and rotating machines

The authors present a paper on the application of online partial discharge (PD) testing and monitoring technology for the insulation condition assessment of in service medium voltage (MV - 3.3kV to 45kV)) and high voltage (HV - 66kV to 750kV) cables and plant. The paper begins with a short summary of the different economic `DRIVERS' which apply to both public utility and industrial HV networks. The paper presents some of the test techniques employed and the on-line PD sensor technology used to test in-service power cables, switchgear, transformers, rotating machines, CTs/VTs and other HV plant. The paper concludes with some case studies of past projects carried out by the authors from on-line PD test projects testing a wide range of MV & HV assets in electricity networks around the world.