Study on thermal circuit model of typical disconnector and current transformer
The internal overheating of power related equipment during dynamic rating is hard to avoid, which would accelerate the aging of insulation and even cause burn out accident. Therefore, thermal field analysis of the equipment is crucial for the safety operation of power system. Disconnector and current transformer are indispensable but easy to be ignored. The internal thermal defects of these devices are likely to become the bottleneck to restrict the development of dynamic rating. In this paper, we established the thermal circuit model of typical disconnector and current transformer, and use the model to calculate the hot spot temperature of these devices. The model takes account of meteorological parameters such as ambient temperature and wind velocity. Steady thermal field and dynamic thermal field are included in the model. The temperature rise test report of short circuit test is applied to modify the model in order to make it more applicable to engineering calculation. Though the calibration, we found that the model calculation results and the experimental data meet well as the deviation is within 10%, proving the accuracy of these proposed models. The thermal field analysis of disconnectors and current transformers will contribute to the safety operation of the entire power system.