Review of passive loop systems for normalization of high-voltage cable line magnetic field

Abstract

The paper is devoted to the review of known passive loop systems that can be used to normalize the high-voltage cable line magnetic field. The purpose is to identify the most promising systems. We review the most cited scientific papers and patents about the reduction of the power line magnetic field. We identify the top research groups engaged in the design of passive loop systems. The two groups are from Italy, the one each is from Spain and Ukraine. The passive loop systems developed by each group have their own features. We classify the systems according to the following characteristics: the number of passive loops in the shielding system, the shape of passive loops used in the shielding system, and the way to increase the shielding efficiency of cable line magnetic field. According to the number of passive loops, the systems can be divided into three types: single-element, double-element and multi-element. According to the shape of passive loops, two types of shielding systems can be distinguished, namely, the systems using rectangular passive loops and the systems using passive loops made of three cables connected in parallel. According to the method of the shielding efficiency increasing, the system can be divided into four types: the first use ferromagnetic cores covering power and shield cables, the second use additional capacitors connected to shield cables, the third use a unique arrangement of loops between the cable line and the shielding area, the fourth use an increase in the cross-section of shield cables, respectively, an increase in the quantity of metal. The review shows the most promising passive loop systems for normalizing the high-voltage cable line magnetic field are single-element systems with additional cores, namely «High Magnetic Coupling Passive Loop» and «Single-loop shield with ferromagnetic cores and asymmetric magnetic coupling». Keywords: magnetic field, shielding, cable line, reference level, power frequency