Study on the resistive leakage current characteristic of MOV surge arresters

MOV surge arresters are the important protective devices for the safe running of the electrical power system. The monitoring and diagnosis of the arresters has been paid more attention since they are put into the network. Various monitoring on-line or off-line diagnostic methods to detect their performances are mostly based on the measurement of the leakage current. The numerical harmonics analysis method is used to study the resistive leakage current characteristics of MOV surge arresters by test in the paper. The relative program flow chart with FFT method is also presented. The degradation factors, such as surface contamination, aging and inner moisture, and thermal deterioration are investigated based on the diagnostic indicator-the resistive current characteristic of the arrester. Data from experiments has proved the accuracy of the measuring method and the software program. Finally the measurement of MOV temperature is discussed primarily to provide another diagnostic criterion for MOV surge arresters. But it has shown that the temperature detection needs a further study for its practical application.