AC and DC Electrical Aging of Polyethylene

The differences between AC and DC aging are pointed out and are partly due to the different dissipated energy under the two types of field and partly due to the fatigue induced by the alternating stress. In addition to these effects, the sample size has also a considerable impact on both aging and breakdown. It is shown, from well known existing data, that the aging characteristics of polyethylene and XLPE under DC field in air could be easily extrapolated from data obtained with the same size sample but aged in air under AC field. This approach has the merit to avoid long DC tests whose results might easily be predicted from much shorter AC tests. It is also suggested that this approach might be used to analyze the results of other electrical properties measurements of various polymers.