An Online Leakage Current Monitoring System of MOV used in Series Capacitor Compensation

This paper presents a novel Metal oxide varistor (MOV) online leakage current monitoring system used in series capacitor compensation. The proposed system includes current transformer, micro-current sensor, leakage current measuring box, optical fiber column and ground monitoring unit. The leakage current of each MOV is measured by micro-current sensor with range of $50 \mu A$ to 6mA. The current transformer is responsible for measuring the main capacitor current. The leakage current measuring box takes the main capacitor current as the reference to calculate the resistive current of each MOV and sends the data to the ground monitoring unit for monitoring the leakage and resistive currents of each MOV in real time with optical fiber column. The tests of the system are carried out in the laboratory. The results show that the proposed system has highly accuracy and can be useful for predicting the defects and performance deterioration of MOV used in series capacitor compensation.