Metal Oxide Arrester Resistive Current Measurement Methods

In this paper, a new method named as Capacitance-Bridge Method is presented to measure the resistive leakage current of Metal-oxide Arrester (MOA); and a mathematic analysis based on circuit model of MOA is introduced in detail. This mathematic analysis can help to figure out how the magnitude and phase deviations of compensation signal in capacitive- compensation methods to influence the result of resistive leakage current measurement.Capacitance-Bridge Method is one of Capacitive-Compensation Methods, and its main advantages are: 1> using the capacitive current of capacitance-arm as compensation reference; and there is no phase difference between the compensation reference and the capacitive leakage current. All this helps the test out of the difficulty of phase adjustment. 2>using Capacitance-Bridge Method, the harmonic influence from harmonics in the voltage by counteracting the harmonic capacitive currents can be reduced greatly; so accuracy can be improved.In mathematic analysis, we studied the relation between the r.m.s of resistive leakage current and the magnitude deviation in compensation reference, and the relation between the r.m.s of resistive leakage current and the phase shift in compensation reference; these relations help to find out how to optimized the compensation in Capacitance-Bridge Method.In the end, comparisons between the result of Capacitance-Bridge Method and the result of mathematic simulation are showed.