Effects of testing on service aged XLPE cables

This paper presents the results of a test program on the effects of tests used in condition assessment of XLPE cables nearing the end of their life. The test program was carried out on submarine cables removed from service. The work consisted of two parts: Part 1 (cable evaluation tests to determine the condition of the cable) which included partial discharge, 60 Hz tan δ, AC breakdown tests, dissection and water tree analysis, and failure analysis of the failure site, and Part 2 (Effects of testing) which included lab tests to determine the effects of switching surges, VLF tan δ, and the LIpA test. Partial discharge tests were carried out on samples before and after switching surge tests, VLF tan δ tests, and the LIpA Test (Part 2). In addition some of the samples that were subjected to the different tests were aged at 14.4 kV in salt water for 284.5 days. The test results are discussed in term of the effects of the different test techniques used in condition assessment of XLPE cables suffering from advanced water tree related degradation.