More than Twenty Years of Experiences with Commissioning Testing of HV & EHV Cable Systems with Near Power Frequency Withstand & Partial Discharge Testing

Over the past 25 years, thousands of kilometres of installed XLPE High Voltage (HV) and Extra High Voltage (EHV) cable systems have been subjected to after-laying commissioning testing prior to energization. The commissioning test usually consists of a combination AC withstand (HiPot) & Partial Discharge (PD) testing. This paper presents more than two decades of experiences with non-monitored and monitored withstand testing on HV and EHV cables obtained globally with withstand levels and durations as in accordance with IEC standards and PD monitoring in accordance with IEEE & CIGRE recommendations. The paper discusses influence of level and frequency of the applied withstand voltage for successfully identifying typical life limiting laying or installation related defects in newly laid HV & EHV Cable systems both in terms of dielectric break-down and also in terms of detection of partial discharge sources from same defects. The paper further provides statistical summary of tests performed on more than 10,000km of HV and EHV cable systems including failure rates and non-pass PD rates of accessories distinguishing between HV and EHV cable systems. The paper also provides several case studies of PD detected in cable accessories during AC HiPot commissioning testing. The paper also discusses the influence of PD sensitivity on the results obtained especially considering that different types of PD sensors and measurement instruments have been used.