Environmentally induced degradation Of locally produced insulating polymers

Abstract

Polymers are widely used for a variety of industrial and engineering applications which include in particular the high voltage apparatus. In the Kingdom, several manufacturers are producing polyethylene based raw materials as well as insulated wires and cables. When such insulations are subjected to electrical stress and environmental parameters such as ionic species, water and temperature etc., their dielectric properties degrade. This paper assesses the impact of such modes of degradation on locally produced polymers that are commonly used by electrical industry. The main mechanisms which are reported for such degradation are identified and results elucidated. It is shown that the aging time as well as the differently manufactured polymers are influenced significantly by environmentally induced stresses. Water tree population and their lengths were subjected to Weibull and log-normal models of statistical distributions and the data were found to fit better on the log-normal model. This suggests that the most likely mechanism for environmentally induced water tree degradation is electromechanical fatigue based. Results, analysis, discussion and conclusions are presented in the paper.