The Effect of Extremely Low Temperatures and Their Sudden Changes on the Failure Rate of 110–220 kV Terminal Cable Couplings

In modern power systems, 110-220 kV cable and overhead power transmission lines are extensively used. Terminal cable couplings are critically important components of such lines, failures of which lead to serious accidents. A striking example of problems concerned with operation of these components is the experience of the Republic of Sakha (Yakutia), where in 2021–2023, 19 damages to terminal couplings on 110-220 kV power lines were recorded. This region is uniquely featured by its harsh climatic conditions with extremely low temperatures, which may drop to as low as –60℃, and their sudden diurnal fluctuations, e.g., from –60 ℃ to –35 ℃ within 3-4 h. The results of accident investigations indicate that the existing cable coupling designs are not adapted to such climatic conditions. The article considers a comprehensive study of the operation of terminal cable couplings under the conditions of extreme and rapidly changing temperatures. The aim of the study is to analyze the effect the ambient temperature gradient has on the cable fitting components and assess the drawbacks of standard designs. Based on the analysis performed, engineering solutions and recommendations for modernizing the couplings have been proposed, which are aimed at ensuring their reliability in regions with a harsh climate, which is of great practical importance for securing uninterrupted power supply.