An Investigation of the Shielding Effect of Magnetic Field using Mu-metal for the Application to 765kV Transmission Line

Abstract

An integrated sensor system "Power Ball Sensor" has been designed and then developed for the direct installation on the 765kV transmission line. Any potential service failure of the power grid could be noticed ascribed to its advanced funtion enabling to monitor the operation and environmental situation. Since it is exposed to the extreme magnetic field disturbance caused by the transmission line, all digital devices that should be carefully protected against high magnetic disturbance by the shielding materials such as Mu-metal or Permalloy in order to guarantee the relevant nomal operation. In this work, the magnetic field shielding effect (SE) has been empirically investigated for the Mu-metal case by applying different number of shielding layers (1-layer to 3-layer) to deduce the design parameters for the "Power Ball Sensor". And also the magnetic field distribution is measured by use of a self-designed magnetic probe as a function of the magnitude of the transmission current generated at the laboratory.