A circuital approach to estimate the magnetic field reduction ofnonferrous metal shields

The reduction of magnetic fields is a topic of concern to the electric utility industry and the electromagnetic compatibility community. One technique to reduce the magnetic fields is to use metal plates and enclosures for shielding, in addition, knowledge or the loading effect of a conducting structure in close proximity to power cables is needed for estimating power loss. Until now there has not been a simple and efficient method to calculate the low frequency magnetic shielding of, nor power loss caused by, two-dimensional shields. This paper presents a method for the rapid numerical estimation of the magnetic shielding efficiency and power loss of nonferrous metal structures. The method was validated analytically and experimentally     

Comparison of calibration systems for magnetic field measurementequipment

The current ANSI/IEEE standard specifies two possible methods for magnetic meter calibration: a single square loop or a round Helmholtz coil. However it: (a) does not specify the size of the coil; and (b) does not provide a comparison of the field uniformities between the two suggested systems. In this paper, the z-directed magnetic field equations for four calibration system designs, the single round loop, the round Helmholtz coil, the single square loop, and the square Helmholtz coil are derived and presented