Estimation of flashover probability of aged nonceramic insulatorsin service

摘要

A procedure for estimating the flashover probability of agednnonceramic insulators in-service is presented. The study was carried outnusing two types of 138 kV EPDM line post insulators received from thenFlorida Power and Light system (USA). Presented are the laboratoryncharacterization of the naturally contaminated insulators, thendevelopment of a linear regression model, and the estimation of thenstatistical parameters that define the relation between probability ofnfailure and applied voltage for a given contamination level. The resultsnobtained in the laboratory were in agreement with the current and pastnfield experience. Conservative probabilities of flashover were estimatednunder the assumption of a cumulative normal distribution. The estimatorsnof the parameters that define the normal distribution were assessed withnthe original up and down method. The results suggest that for one typenof EPDM insulator, contamination flashover performance was distinctlyninferior to the other