Optimal Design of Magnetic Field Sensor for Condition Monitoring of High Voltage Power Cable

With the wide use of power cable, the cable monitoring is essential to the reliability of power supply. Although the traditional electric field detection method can realize the detection of cable aging, defects and faults, the detection method and process are complex and the detection reliability needs to be further improved. Therefore, based on the change of cable magnetic field, this paper carries out the optimization design of the magnetic sensor, which is helpful to the fast and effective detection of the cable system. In this paper, COMSOL Multiphysics software was used to establish the model of the magnetic field sensor. The effect of core aspect ratio on effective permeability was studied. The influence factors of resistance and inductance were analyzed. Using Multisim, a signal amplifying circuit with magnetic flux as feedback loop was designed. The results show that when magnetic core is made of permalloy, the optimal aspect ratio of the core is 20, which can maximize the effective permeability. The simplified formulas of resistance and inductance are obtained. The amplifier circuit improves the amplitude-frequency characteristics and phase-frequency characteristics of the coil.