A Non-Destructive Method for the Life Estimation of RIP Transformer Bushing

Resin Impregnated Paper (RIP) is increasingly used in transformer bushings in the recent past. The overall reliability of a high voltage power transformer largely depends on the sound operation of the bushing. RIP insulation is relatively a new entity in the field of high voltage bushing. Hence, it is essential to ensure life of the bushing by conducting destructive or non-destructive type of life estimation studies. This paper reports the result of a life estimation study of RIP bushing based on partial discharge monitoring. The stepped stress model, the concept of abstract damage proposed by Miner, is extended to analyse the degradation of electrical insulation. Partial discharge data measured for a long period of 480 days under stepped stress is used for this analysis.