机车电传动 (Jan 2023)
Study on variations in moisture-affected fault characteristics of EMU lightning arrester
Abstract
In order to study the changes in the fault characteristics of the EMU lightning arresters exposed to moisture, an artificial moisture test platform of lightning arresters was built, on which the lightning arrester can be controlled to reach three states of light, mild and severe moisture respectively. The test was performed to study the characteristics of lightning arresters under different moisture conditions, including DC volt-ampere characteristics, DC reference voltage, leakage current under 0.75 times DC reference voltage and leakage current under AC voltage. Moreover, the water boiling test was carried out under the design conditions, and the results were compared with the artificial moisture test results for verification. According to the artificial moisture test results, the lightning arrester after moisture experienced significant changes in the volt-ampere characteristics curve; the leakage current contributed by the valve disc body and the cylinder wall was dominated by the epoxy cylinder with the increase in voltage; the DC reference voltage (U1mA) decreased by 6.8% in severe moisture, lower than the specification requirements of 5.0%; the leakage current at 0.75 times U1mA increased by 6 times in light moisture than that in the normal state. According to the water boiling test results, for the lightning arrester dried from the moisture state, the leakage current at 0.75 times U1mA also returned to the normal values, that is, the fault characteristic is only sensitive when the lightning arrester is in the moisture state; the resistive current accounted for 10%-20% of the total current in the normal conditions, and this proportion rose 4 times in the moisture state, that is, the resistive current is more sensitive to the moisture-affected fault.
