Hotspot location and mitigation for underground power cables

Cable current-carrying capacity (ampacity) is limited by hotspots. Based on distributed temperature sensing, the hotspots of a 230 kV 500 MVA underground cable circuit were located. The derating at each hotspot was calculated using a new technique, which helped to determine more accurately the thermal environment parameters at the hotspot. Case studies are presented to show the successful restoration of full cable rating after the hotspots were mitigated.