With the increasing demand for urban living and production power, the power grid is developing rapidly, which also puts forward higher requirements for the stability of distribution lines. As the main channel of power transmission in the city, power cable develops rapidly with an average annual increment of 35%. Cable failure is often caused by connectors, and 6-10KV distribution cables have one connector every 300-500m. Therefore, there are countless cable joints in the complex distribution network, and the existing security risks cannot be underestimated. The decrease of insulation level is often the main cause of power cable joint failure.

When the insulation level drops, the leakage current increases, the loss increases, and finally the temperature rises; when the temperature rises, the insulation aging will be accelerated, the leakage current increases, and the temperature rises again, and finally the insulation breakdown will be caused. Therefore, the temperature of the cable joint can be used as a parameter of the running state of the cable to monitor the running state of the power cable.