2007 Volume 127 Issue 9 Pages 994-1001
The power-frequency withstand voltage tests are regulated on electric power equipment in JEC by evaluating the lifetime reliability with a Weibull distribution function. The evaluation method is still controversial in terms of consideration of a plural number of faults and some alternative methods were proposed on this subject. The present paper first discusses the physical meanings of the various kinds of evaluating methods and secondly examines their effects on the power-frequency withstand voltage tests. Further, an appropriate method is investigated for an oil-filled transformer and a gas insulated switchgear with taking notice of dielectric breakdown or partial discharge mechanism under various insulating material and structure conditions and the tentative conclusion gives that the conventional method would be most pertinent under the present conditions.