Grading capacitor is an important equipment of high voltage circuit breaker and its insulation status has important influence on the reliable operation of circuit breaker.The reliable assessment of its operation status is of great significant for the safety of network maintenance.The measurement of dielectric dissipation factor is a sensitive and effective approach to judge the electrical insulation conditions of electric equipment.In this paper

the reason of abnormal dielectric loss test caused by Garton effect on voltage equalizing capacitor of 500 kV high voltage circuit breaker is analyzed

the method of judging Garton effect and corresponding strategies are proposed in field testing

which provides reference for condition evaluation and operation maintenance of voltage equalizing capacitor of 500 kV high voltage circuit breaker.