Low-Frequency Magnetic Shielding Effectiveness of Braided Three-Phase Power Cable Based on 12-Pulse Bridge Rectifier Circuit and PWM Inverter Circuit

The near magnetic fields of power cables and shielding effectiveness (SE) of cable's braided shield structure are discussed in this paper. The excited current at extreme low frequency (0-400Hz) is provided by a 12-pulse three-phase bridge rectifier or a pulse width modulation (PWM) inverter circuit. Under such excitation, the effects of harmonics can be assessed. Meanwhile, braided metal wires are characterized in terms of hundreds of current filament in 2-D simulation model of cable. Therefore, skin effect and proximity effect are considered in this configuration, which contributes to accurate and high computational efficiency for calculating magnetic fields. Result shows that highly braided copper shielding layer (88%) together with copper strips can lead to large reduction of magnetic fields compared with unprotected counterpart.