Abstract: The present invention performs a reference point detecting step (S20) to select a reference point by performing pattern analysis based on a characteristic pattern shown in a total leakage current (IT) when an applied voltage is 0V, a resistive leakage current calculating step (S30) to calculate a resistive leakage current by Fourier series-expanding the total leakage current (IT) starting at the reference point, and reference point verifying/correcting steps (S40 and S41) to correct the reference point until a characteristic pattern of the resistive leakage current (IR) according to non-linear resistance characteristics of the surge arrester (1) is shown so that the resistive leakage current (IR) is recalculated, and the present invention determines that the resistive leakage current (IR) calculated based on the completely corrected reference point is the resistive leakage current of the surge arrester (1).

Abstract: The present invention relates to resistive leakage current in a surge arrester that measures not voltage but leakage current alone in the surge arrester to obtain a resistive leakage current included in the leakage current so as to compensate for shortcomings in conventional metal-oxide surge arresters.