Experimental and statistical considerations in ageing studies on electrical insulation

Life testing of electrical insulation continues to be a topic of high priority for high voltage engineers. While many papers exist in the literature which discuss ageing models and ageing processes of insulation, experimental and statistical considerations in conducting life tests appear to be reported less frequently. In this paper, we discuss certain experimental aspects to be kept in mind while conducting ageing experiments under single as well as combined stresses. We also discuss the need for a careful statistical treatment of life data to draw meaningful conclusions from the same