In view of such problem that the currently common 220 kV metal high voltage cable joint protection device with two energy discharge holes is lack of optimization design method

the design principle and method optimizing the opening size of the energy discharge hole and wall thickness of the protection device based on three-layer iterative algorithm is proposed by using finite element method coupled with temperature field

flow field and displacement field. The air（gas）pressure distribution on the inner wall of the 220 kV high voltage cable joint protection device under different opening sizes is calculated. The opening size of the energy discharge hole r=80 mm is obtained and the optimal energy discharge effect is achieved. Moreover

based on the design parameters of the energy discharge hole

the stress distribution on the inner wall of the device is simulated and calculated. The optimal matching wall thickness of the protection device is finally determined as d=6 mm with the ultimate stress value which the material of the device can withstand as basis. The reliability of the design is proved by 50 kA/200 ms high current arc test. The overall material consumption of the protective device after the optimization is 40% less than that of the original device

and the temperature rise effect of the cable joint after installation of the protective device is further reduced. The design method and key parameters presented in this paper can provide methodological guidance for the optimal design of the high voltage cable joint protection device and improve its technical and economic benefits.