Live washing of h.v. insulators in polluted areas

Outdoor insulation is designed to withstand normal atmospheric-pollution conditions by using natural rainfall as a cleaning agent. The pollution may be the result of long-term exposure to variable weather and industrial conditions; it may be caused by severe salt-carrying storms, concentrated industrial deposits may be precipitated by certain circumstances, and fog produces a very onerous condition. The usual method of preventing flashover due to pollution is to clean the insulation surface by hand. In certain circumstances, washing shows advantages, and investigations have taken place to determine the possibility of washing outdoor insulators under live conditions and the effectiveness of this washing under various pollution and weather conditions. The object of the paper is to give the results of these investigations, to assess how the efficiency of washing is affected by the frequency and duration of various methods of washing, to consider the economic aspects of live washing and to give guidance as to the operating margins. A brief account is also given of live washing of outdoor h.v. insulation in Britain, and of the experimental results.