Investigation and analysis of thermal aging of XLPE and PVC cable insulation materials manufactured in Saudi Arabia

Abstract

Electrical power distribution systems utilize thousands of kilometers of cable materials of different voltage levels. Power cables generally consist of a metal conductor surrounded by an insulation layer. Petrochemical industries in Saudi Arabia and others provide raw materials for cable industries. Polyvinyl chloride (PVC) has usually been the polymer of choice in power cable construction due to its easy processing and good insulation performance. Even now, with the trends toward using Cross-linked polyethylene (XLPE) and other polymers, PVC still makes up approximately 50 % of the polymer volume used in cable construction. The whole year around severe weather environment of the Kingdom adds tremendous factors in stressing cable materials and shortens their lifetime. The Kingdom petrochemical industries are striving to improve the quality of the plastic raw materials. On the other hand, cable industry has also made noticeable progress in the production of higher voltage level cables. As far as high voltage cables are concerned, electrical field strength and temperature are, in general, the prevailing stresses producing insulation aging. These effects cause partial discharges in the insulation material that will lead definitely to a short circuit. Unexpected cable faults may cost utilities, as well as customers, large financial losses. The proposed study will provide and conduct direct testing and investigation of thermal aging on widely used cable insulation materials (PVC and XLPE) to determine their endurance characteristics, Raw and manufactured insulation materials will be brought from major Saudi cable factories. Mainly, weight loss and electron spin resonance (ESR) spectral studies and analysis will be carried out to characterize and simulate the thermal stress to evaluate the quality and life-time of the insulation materials. The results of PVC and XLPE can be extended from life tests to the application of these materials for higher quality and to the improvement of cable materials.