Influence of surface and internal defects on polyethylene electrical routine test on VHV cables

In order to improve the reliability of polyethylene cable insulation two types of harmful defects must be eliminated: 1- Imbedded conducting contaminants present during the course of routine test on drums. 2- Accidental superficial defects which may appear on the cable moulded accessories. A laboratory study on special samples and on commercially-made cable and accessories determined: 1- The harm of humidity on superficial defects. 2- The conditions of application for the routine test, i. e. the applied voltage level and the duration of time. Examination of the life curves obtained on sample containing short defects, simulated by a needle tip, proved the possibility of elimination of harmful impurities without aging the insulation.