Research on the performance of high-voltage insulators in polluted atmospheres

The paper describes the work which has been carried out at the Croydon Insulator Testing Station during the last 15 years on the performance of insulators in humid and polluted atmospheres. Various types of line and substation insulators have been investigated, and the results obtained with insulators for working voltages of up to 380 kV are presented. Methods of surface treatment to improve insulator performance are also discussed. Work on experimental insulators made from plastics is described. An account is given of recent work on insulators for high-voltage d.c. operation. The use of artificial salt-pollution tests to simulate service conditions is also discussed.