Thermal Effect of Short-term Overload on High-voltage Cross-linked Polyethylene (XLPE) Cable Insulation

This paper describes changes on micro-structure and aggregation structure of cross-linked polyethylene (XLPE) with different thermal histories after different times of overheating treatment to analogize the short-term fault or emergency overload in actual operating cables. 5, 10 and 20 times overheating treatment were conducted on a spare cable and a retired cable with service years of 32, whose insulation were analyzed by the diagnostic measurements of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TG). The results show that the spare cable has presented a trend of improvement on the insulation properties after overheating treatment below 20 times, but slight deterioration occurs after 20 times overheating treatment; the retired cable with service years of 32 has presented a trend of degradation on the insulation properties at the first 5 times overheating treatment, and a severe deterioration occurs after 20 times overheating treatment.