Effect of Voltage Stress on Diagnostic Parameters of Low Voltage Cables

The most important property of the insulation is the dielectric strength, because the main function of the insulation is isolating of the electrodes on different potential. Due to the stresses the dielectric strength is decreasing till it reaches the limit of safety operation. Aging tests are performed on insulations to predict the expected lifetime of the insulation in service. The enhanced voltage stress is widely used as the means of accelerated aging test. In the accelerated aging test the controlled parameter is the voltage stress and the determined variable is the time to breakdown. The aim of the present investigation was to determine the effect of voltage stress on the parameters measured by diagnostics methods. The samples for the examination were taken from polymeric insulated low voltage cables. The samples were periodically aged by voltage stress and insulation diagnostics tests were performed on the samples after every aging period. The results are discussed in this paper.