With hemispherical EFP simulation model, the penetration process of EFP that satisfies the simulation ratio are calculated using explicit finite element program LS-DYNA in this paper.

The numerical results indicate that, the shaping of the prototype and the simulation EFP accord with the analogue rule, and the depth of penetration on steel target also satisfy simulation ratio.

ATP simulation and MATLAB calculation show that the voltage ratio protection against inter-turn fault of reactor can make correct judgement to this kind of fault quickly.