Abstract
The small capacitive current switching by the vacuum switch is simulated using Electromagnetic Transients Program (EMTP) into which Mayr's equation is combined through the function of TAGS. Mayr's equation to describe the dynamic behavior of an arc in vacuum switches is a function of arc conductance, arc time constant and arc energy loss. The arc time constant and the arc energy loss are assumed as a function of arc conductance.
To obtain the arc parameters experimentally, a resonant high frequency circuit constructed by a capacitor and a reactor is added to the test circuit. The arc parameters are obtained by the resonant high frequency component of the arc current and the arc conductance.
While the arc current becomes small, the spike voltages appear on the average arc voltage. The spike voltage stimulates arc current to generate the resonant high frequency current component. The resonant high frequency current component becomes larger with the passing of the time, then the current chopping occurs when the resonant high frequency current passes through zero.
The arc current is simulated by the reproduction of the spike voltages according to the measured arc voltage waveform in simulating processes. The simulation of the spike voltages are realized by a small resistance and two current sources. The result of the simulation of the switching arc phenomena by the vacuum switches gave good agreement with the result of the measured arc current near the current chopping. In consequence of this simulation, the small capacitive current interruption by vacuum switches is closely influenced by the spike voltages.
