Magnetic shielding principles of linear cylindrical shield at power-frequency

Abstract

Magnetic field shielding of cylindrical shields has been studied for a long time, and analytical solution has been derived at power-frequency. This paper, based on previous work, presents an analysis of the shielding principles of a linear cylindrical shield at power-frequency. The shielding principles are developed from simplified shielding formulas under a single-shell and inside-source configuration. Partition of parameter space is introduced, and four regions (linear induced-current, nonlinear induced-current, flux-shunting and induced-current/flux-shunting shielding) are identified geometrically. It reveals the inherent relationship between the shield parameters and shielding effectiveness. A sensitivity study of the shield parameters is conducted too. It discloses the inherent patterns of the parameter impact on the shielding effectiveness. Convenient design curves are presented in the 2D space. These shielding principles and design curves will alleviate the shielding design burden.