Analysis of influence of porosity on electric field and temperature in pre-insertion resistors

In UHV and UHV transmission lines, tank circuit breakers need to be switched frequently, and the pre-insertion resistors is subject to the mixed impact of AC and DC at the same time, so the pre-insertion resistors is easy to be damaged, which affects the reliability of the power system. The pre-insertion resistors needs to withstand a lot of heat when acting, and the temperature distribution and heat dissipation capacity inside the pre-insertion resistors are particularly important. Based on this, this study first observed the internal morphology of the pre-insertion resistors through electron microscopy, established a Voronoi diagram model according to the internal morphology, built a simulation model of the pre-insertion resistors and calculated the temperature and electric field distribution of the pre-insertion resistors under different porosity. The results show that after injection of impulse current pulse with peak value of 2.03kA, the highest temperature inside the pre-insertion resistors at 366.5°C appears at the pore next to the carbon black conductive chain. Higher rate of porosity will make the temperature inside the pre-insertion resistors more evenly distributed, but will bring about an increase in the strength of the overall electric field inside.