Testing a 110 kV external gas pressure cable to evaluate continued operational reliability

After several disruptive discharges during operation of an external gas pressure cable manufactured in 1953, it was decided to investigate the causes of these failures in the laboratory. At the same time, the opportunity was taken to apply various methods of diagnosis that have been developed for evaluating ageing, plastic insulated cables so as to test whether the use of such measurement methods suited to on-site applications can also supply meaningful results for this type of layered dielectric. The authors discuss the cable design, describe the failure, and discuss the test methods to check the diagnostic procedures