Study On Magnetic Field At Power Frequency For 220kV And 110kV Underground Power Cable

220kV and 110kV underground power cable lines generate magnetic field at power frequency.Considering the influence of this magnetic field on people in tunnels,it is significant to study this magnetic field level and the way to control it.In this paper,the magnetic field at power frequency of 220kV and 110kV underground power cable lines in 5 cable tunnels in Beijing are measured and calculated,and the magnetic field levels of cable lines in operation are analyzed.The influence of the cable arrangement,the phase-sequence and the width of tunnel on magnetic field around the cable is investigated by calculation,and the counter magnetic field measures for human body are proposed.