Assessment of DC Magnetic Fields under a 200kV DC Overhead Transmission Line

Abstract

DC magnetic fields under the Hida-Shinano 200kV DC overhead transmission line were assessed by measurements. The DC magnetic fields observed under the DC overhead transmission line are a superposition of the geomagnetic field and that generated by the DC line current. In this study, the DC magnetic fields generated by the transmission line were obtained by a vector subtraction of the geomagnetic field from the total DC magnetic field. The measured geomagnetic field was 47.1μT and the assessed magnetic fields from the line with a current of 2250A were from 3.8μT to 8.3μT depending on the operating condition of the DC transmission line.