Shielding Effectiveness of Double-Layer Magnetic Shield of Current Comparator Under Radial Disturbing Magnetic Field

The traditional magnetic shield of the current comparator usually adopts the single-layer magnetic shielding structure. However, with the external magnetic interference becoming increasingly severe, the double-layer magnetic shield of the current comparator exhibits greater practical value and favorable application prospects. In order to study the shielding effectiveness of the double-layer magnetic shield of the current comparator, a calculation method about the magnetic shielding effectiveness under the radial disturbing magnetic field is presented. This calculation method is based on the magnetic circuit analysis principle, and its accuracy is better than 30%, compared with the corresponding results of finite-element method simulations. Through analyzing factors affecting the shielding effectiveness, it is approved that a greater shielding effectiveness under the radial disturbing magnetic field is achieved when the thickness of air gaps is approximately equal to that of shielding cores. Besides, when the double-layer magnetic shield has the same external dimensions as the single-layer magnetic shield, the radial shielding effectiveness of the double-layer magnetic shield is as two times as that of the single-layer one, while its material consumption is only 6/7 of the latter.