Experimental Study on The Performance of External Open-Circuit Failure Gas Discharge Tubes under Power-Frequency Follow Currents

Abstract

A short-circuit fault in the gas discharge tube (GDT) is one of the latent hazards of electrical equipment. It may cause the ignition of electrical equipment. Therefore, based on the existing GDT, an improved external open-circuit failure gas discharge tube (EOFGDT) which can remove short-circuit (SC) failure is presented in this paper, and its structure and working mechanisms are introduced. This EOFGDT can utilize the combustion and heat transfer of continuous arcs due to SC failures to increase the temperature of its end electrode, so as to induce a solder joint failure, by which the elastic sheet on the solder joint becomes disconnected from the end electrode, forming an external gap that reduces the rising speed and amplitude of the recovery voltage across the arc gap, and eventually forms an open circuit (OC) within the structure. The EOFGDT SC condition was simulated and a test of the EOFGDT ability to remove SC faults by using an 8/20 µs impulse current generator coupled with a power-frequency power supply test bed was conducted. The experimental results show that the magnitude of the SC follow currents, power-frequency voltages, and the impulse currents are positively correlated to the OC response time, which is greatly affected by the power-frequency follow currents. When the SC current reaches 30 A, the EOFGDT OC response time is about 350 ms. The experimental waveform is consistent with the screen result of the OC response time of the EOFGDT, which proves the effectiveness of EOFGDTs for the inhibition of SC follow-current failures.