Investigation of central frequency and central loss factor values on dioctyl-phthalate (DOP) plasticized PVC films

Cables are important assets for the electricity provider companies, therefore monitoring the condition of them is an important issue as well. Loss factor (tan δ) measurement is a widely used technique in insulation diagnostics. In this paper PVC films were investigated with different DOP plasticizer contents (0, 30, 40, 50 wt%) before and after thermal aging by means of an electrical (loss factor) and a mechanical (Shore D hardness) measurement method. From the results of loss factor measurement new deducted quantities, the central frequency and central loss factor values were calculated to examine the shifting and the intensity changes of tan delta vs. frequency curves for different plasticizer contents. The results suggest that these values can be used to pre-indicate the degradation of PVC insulations.