Contamination & Hot Wash Performance of Zinc Oxide Station Arresters

It has always been necessary to consider the effects of external contamination in the design of surge arresters. Before the development of metal oxide arrestermapable of continuous operation without series gaps, the primary criterion for satisfactory per0formance was that the series gaps did not spark over when the arrester housing was contaminated. Several procedures were developed for contamination testing, and one of these procedures was acceptenceas an ANSI standard (2) Although the test procedure of ANSI C62.1 is satisfactory for arresters made using series gaps, it is not adequate for testing metal oxide arresters, in addition, no formal method has been agreed upon for washing energized arresters which are subjected to unusually severe contamination. The objectives of this paper are: to point out the differences in performance under contaminated conditions of arresters made with and without series gaps; to suggest a revision of the ANSI Standard to include a test appropriate for arresters made without series gaps; and to describe tests made to demonstrate the ability of metal oxide arresters to permit washing while energized.