XWP3-160 155 280 450 20 100 50 45 120 150 130 ≈20 80 120 160 8.2 main dimensions (mm) frequency voltage kV rms no less than full-wave lightning impulse voltage kV peak pressure of not less than flashover increase rate (%) Tensile mechanical load (kN) Weight (kg) structural height (H) disc diameter (D) Nominal creepage distance (L) connection type labeled stem wet flashover flashover breakdown 1min wet withstand 50% flashover withstand routine test lh electromechanical electromechanical test no less than the destruction itself has a high frequency corona current, weak signal characteristics, measuring sensors should satisfy a wide range of frequencies, signal amplification large basic requirements. Using electromagnetic induction principle design of the sensor, the sensor core magnetic material must have a wide frequency range, relatively high permeability, low residual magnetism characteristics, which must choose the best from a soft magnetic material; and soft magnetic materials, the slope - Mo alloys, amorphous alloys, metal type soft magnetic materials due to limitations of the production process, currently under such conditions as to meet the high permeability can only reach 20kHz frequency range around [35], but the frequency of the pulse corona current can reach MHz; non-metallic materials meet the high frequency response of the ferrite although requirements, but the highest permeability product can only reach 104 orders of magnitude, how to choose the right material to make the sensor core is designed first question . Taken together, the authors believe ferrite better.