Water trees in medium voltage XLPE cables: Comparison of different polyethylene insulation using short time accelerated ageing tests

This paper describes a pragmatic method to assess the resistance of medium voltage polymeric cable insulation to water treeing. Water trees (WT) with a length between 100 and 800 ¿m are produced in 12 days in the polyethylene insulation of commercial cable samples by use of a high frequency, high voltage power supply. The initial objective was to provide a source of information for asset management eg estimating the remaining life of installed cables. However, the very short time necessary to generate water trees with this method will allow its use for the assessment of new products and provides a rapid comparison technique between different materials. The obtained results show that WTs grow in all kinds of cables but depending on the insulation type, the shape and speed of growth are different.