In recent years, the roof lightning arrester failure of a moving train set has occurred from time to time, and one of the causes of the failure is roof overvoltage. In order to study the characteristics, a roof overvoltage online monitoring system was built to collect the roof overvoltage waveform of a moving train during the driving process. The waveform of overvoltage on the roof of EMU is collected and a model is established to simulate the current of lightning arrester under overvoltage. Collected overvoltage can be divided into over-phase overvoltage, high harmonic overvoltage, lifting bow overvoltage and steep wave impact overvoltage of four typical overvoltage, analyses the characteristics of four kinds of typical overvoltage, The simula-tion results show that the current of the lightning arrester under the action of overvoltage is related to the amplitude of over-voltage, and the surge current of the lightning arrester under the steep wave impulse voltage and over-phase overvoltage is higher.

online monitoring; lightning arrester; overvoltage; explode