Effect of electrical stress on sound propagation of polymericinsulating materials

摘要

The application of ultrasonic nondestructive test techniques todetect the degradation of the insulating materials has beeninvestigated. Using the accelerating test, samples of polyvinylchloride,polyethylene, and acrylic were put under electrical stress withdifferent stress levels and different durations. Using the echo-pulsemethod, ultrasonic velocity was measured for every specimen, before andafter the electrical stress. A change in the ultrasonic velocity insidethe insulating material was observed after applying the electricalstress. These observations indicate that ultrasonic velocitymeasurements could be used to detect the degradation as well as thedensity of the insulating materials