In order to analyze the explosion accidents of the CRH5 EMU roof arrester in recent years, an internal temperature measuring platform based on fluorescence fiber was established, and the temperature distribution characteristics under the continuous operating voltage and high-current impulse were analyzed. The test results show that passing section overvoltage and steep impulse overvoltage have higher amplitudes, while high-harmonic overvoltage has a lower amplitude but a longer duration. The maximum temperature rise of the arrester was 5.2 °C under 34 kV for 3 h. The surface temperature of the valve plate column was high in the middle and low on both sides; the maximum temperature difference at different positions was only 2.2 °C. The maximum temperature of the valve plate column rose to 97.6 °C under 105 times of the high-current impulse, and the maximum temperature difference at different positions reached 33.8 °C. Then, the actual overvoltage of the arrester in operation was measured and analyzed statistically, and the arrester simulation model was established. The temperature characteristics of the normal arrester and the arrester with the electric tree were studied under the actual typical overvoltage, and the influence of air velocity on the internal temperature rise was analyzed. The simulation results show that, due to the low amplitude and small current of high-harmonic overvoltage, the internal temperature rise of the normal and defective arresters was very small. Under the effects of passing section overvoltage and steep impulse overvoltage, the internal temperature of the normal arrester can reach 36.57 °C and 241 °C, and the arrester with the electric tree defect can reach 44.75 °C and 536 °C, respectively. The air velocity has little effect on the internal temperature rise of the arrester. Passing section overvoltage and steep impulse overvoltage occur frequently and have an obvious influence on the internal temperature rise of the arrester, so the roof overvoltage of the EMU is an important reason for the arrester burst.

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Metal particle contamination is an important reason for insulation failure of gas-insulated transmission lines (GILs). Particle trap is the common method for particle suppression. At present, research on the motion characteristics of metal particles near a particle trap and the optimization of trap parameters under AC voltage is insufficient. Based on that, firstly, a dynamic model of metal particles under AC voltage was established, and the motion characteristics of particles in front of the trap were studied, combined with experiments. Then, the influence of trap parameters on the capture effect was analyzed, and the optimization of the trap was realized by simulation. The results showed that, under AC voltage, the randomness of metal particle movement was strong, and the activity was low. The particles mainly moved away from the trap. Among the particles moving towards the trap, some stayed in front of the trap, and some fell into the trap from above. The thickness and height of the trap were the key parameters affecting the capture effect, and with the increase in height and thickness, the capture rate showed a trend of increasing first and then decreasing. The above conclusions can provide a reference for the optimization of a metal particle trap under AC voltage in engineering.

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