Diagnostic testing of composite insulators used on series compensation platforms in Hydro-Quebec

In the early 1990s, Hydro-Quebec installed series compensation on its 735 kV lines. The compensation apparatus is mounted on large platforms insulated from ground by porcelain columns and composite insulators. Following problems encountered with some of the composite insulators enclosing optic fibres, it became obvious that testing means were needed to assess the condition of the composite insulators. Experimentation was therefore conducted in order to evaluate three different diagnostic techniques. The paper describes in details how the tests were performed and discussion of the results obtained both in the laboratory and in a substation, is also given along with conclusions and recommendations