Influence of the length and thickness of nonlinear material on electric field distribution in cable terminal

For high-voltage power equipment, insulation is an important issue. The use of non-linear material can improve the electric field distribution in the device to increase the insulation utilization factor of the insulation structure. This paper takes the cable terminal as the research object, studies the influence of the thickness and length of the nonlinear material on the electric field distribution, and finds the best solution for the cable terminal. Use COMSOL to build a simulation model of DC 500kV cable terminal. Through the controlled variable method, the length and thickness of the nonlinear material are changed in the range of 300mm to 500mm and 4mm to 8mm respectively, and the corresponding electric field distribution is obtained. The results show that the end of the nonlinear material is the weak point of the high-voltage cable terminal. Within the set range, the electric field strength there decreases with the increase of the length, and also shows a decreasing trend with the increase of the thickness. The increase will increase the field strength of the surface where the external insulation is in contact with the air, so for the DC 500kV cable terminal, the best solution is when the nonlinear length is 500mm and the thickness is 4mm.