Industrial experience in the testing of water treeing

Attempts to test and evaluate materials and cables in relation to the growth of water trees have been in progress for at least 20 years. However within the UK customer requirements to `type test´ cables to verify their performance in water have only arisen within the last 6 or 7 years. The first of these tests was introduced as a requirement by Eastern Electricity and was of 3000 hour duration. Subsequently tests of 7000 hours and, more recently 17600 hours have been introduced. The author discusses the principal requirements of these three test methods. The author also compares the relative effort required to complete the 3000 and 17500 hour tests. The result shows that roughly 10 times the effort is required for the new test