New electrical testing techniques for fibreglass reinforced plastic operating sticks

This paper outlines how the in-service failure of a 2.3 m 275 kV foam filled fibreglass reinforced plastic (FRP) live line strain stick led to an extensive investigation into the insulation construction, the mechanical and electrical characteristics and the electrical testing techniques for live line and test sticks insulated for operation at high voltages. The investigation revealed inadequacies in the high voltage testing techniques employed on this type of FRP equipment. Relevant electrical characteristics of the FRP insulating materials and assembled tools were derived for development of diagnostics to ensure early detection of insulation deterioration. Having established the electrical parameters, specific testing techniques were designed to provide acceptable sensitivity, accuracy and repeatability. The final stage was to develop a practical testing regime for the tools and equipment with due consideration to their operating exposure and severity of duty. The increased sensitivity in detecting insulation deterioration has enabled the repair of suspect sticks prior to failure