On-line diagnostics of high-voltage bushings and current transformers using the sum current method

Abstract

Experience with the application of the sum current method to on-line diagnostics of high-voltage bushings and current transformers is presented. The method and analysis are described along with field experience obtained at fourteen substations, comprising 56 sets of (three) bushings and current transformers. The influences of temperature, humidity and changes in more than one bushing are discussed.