Importance of Surrounding Media in Accelerated Aging Tests on Metal Oxide Resistors for Surge Arresters

摘要

Metal oxide surge arresters without gaps are continously stressed by the power frequency system voltage and have to face directly all types of overvoltages or uneven voltage distribution along their axes (e.g. due to pollution on the porcelain housing). This fact causes them to be affected by aging phenomena that may lead, through changes in time of the volt-ampere characteristics, to overstressing or even to thermal runaway and consequent destruction of the component. Accelerated aging tests are then of great importance to identify non-correct behaviors with respect to this aspect. Recent research has pointed out that, since it may play an important role on the final test result, the media used to surround the test sample during long duration tests must be carefully chosen on the basis of system experience and of other laboratory investigations. (ERA citation 14:017336)