Abstract: In order to prevent the arrester on the roof of high-speed electric multiple units from breaking down under the high-order harmonics voltage and endanger the operation of Railways, the failure mechanism was investigated through experiments. Firstly, high-frequency voltage withstand test for on-board arrester was conducted. Secondly, the effect rules of voltage harmonics on the magnitude and phase angle of the leakage current of arrester were studied. Finally, based on Matlab/Simulink and experimental data, a high-frequency equivalent circuit model of arrester was established, which provides theoretical basis for the follow-up research. The measured data show that under the harmonics voltage for 7-16 times, the magnitude of leakage current increases linearly and the phase angle decreases, the proportion of resistive current to capacitive current increases, active power generated by lightning arresters rises up significantly with increasing frequency of harmonics. Arrester produces enormous amounts of thermal energy inside in a short time due to high frequency harmonics, and will break down once accumulated heat reaches the heat-resistant limit. Therefore, such accidents can be avoided by improving power quality.

Key words: arrester, higher harmonic, electric multiple units, impedance current, high-frequency fault