POLLUTION TEST ON COMPOSITE INSULATORS: THE ITALIAN EXPERIENCE

The paper reports the results of systematic investigations performed in Italy to assess the behaviour of composite insulators with particular attention to severe environments. The pollution salt fog test with the so called quick flashover method was privileged. Tests were made both on new insulators and on insulators aged in the laboratory and in service, confirming that the pollution withstand is not a unique value for a composite insulator, but depends very much on its surface conditions, and mainly on its hydrophobicity. Salt fog tests were used both to compare insulators of different characteristics and as a diagnostic tool to assess the insulator condition after laboratory ageing or after being in service. Tests were carried out both under AC and DC voltage, confirming the higher…