Investigation of Insulation Deterioration in 15 KV and 22 KV Polyethylene Cables Removed from Service

This paper reports the results of extensive examination of 15 kV and 22 kV polyethylene insulated cables which had been in service for periods of time ranging from less than one year to eight years. Evidence of treeing and related insulation deterioration at normal operating voltage is presented. The investigation is continuing and more data is required before conclusions can be drawn regarding the extent and severity of polyethylene insulation deterioration.