Abstract :
A technique has been developed to measure the 60c/s a.c. intrinsic electric strength of organic polymers. This technique consists in embedding the electrodes and film to be measured in a thermoset resin. The solid construction eliminates prebreakdown discharges on the film surface from the breakdown of liquid used in conventional electric-strength measurements. The measured a.c. intrinsic electric strengths are substantially greater than conventional values. Contrary to previously published data, the peak 60c/s a.c. and d.c. intrinsic electric strengths of polyethylene were found to be equivalent, i.e. 9.0 MV/cm, at room temperature. The a.c. intrinsic electric strengths of a number of hydrocarbon and fluorocarbon polymers were measured and are discussed.
