Modified Phase Shifting of Leakage Current to Condition Monitoring of Metal Oxide Surge Arresters in Power System

Metal Oxide Surge Arresters (MOSA) are proven to be reliable protective devices for power distribution and electrical transmission system. MOSA are subjected to electrical ageing or degradation due to constant AC conduction or transient voltages. Leakage current measured from surge arresters are used to observe its degradation and the resistive leakage component is extracted from the total to determine the health of the surge arresters. If resistive current increases, life of the surge arresters decreases. Generally, leakage current is measured using current shunts or current transformers where it's necessary to measure the applied voltage which is very hard to measure in online condition. This paper develops an easy and accurate method to separate the resistive leakage current from the total leakage current without any voltage measurements by using a technique called Modified Phase Shifted Method (MPSM) and simulated in MATLAB which enables online monitoring system and easy to apply into a device.