Analysis of incipient behaviour of multiple distribution insulators

This paper presents research characterizing the leakage (incipient behaviour) of single and multiple distribution insulators through staged experiments. Four sets of field experiments were conducted over a two year period in which single and multiple insulators were artificially contaminated and energized on a lateral of a distribution system. More than 70 recordings were obtained from monitoring at the site of the insulator(s) under study and at the substation feeding the lateral. This paper focuses on the characterization of the site recordings. Individual insulator leakage currents showed an erratic behaviour with bursts lasting from half a cycle to several seconds. The multiple insulators conveyed a cumulative behaviour caused by individual insulators in various stages of leakage. The results are characterized graphically in the time and frequency domains.