Abstract
A molded-case circuit breaker has deion plates to raise an arc voltage. To understand the phenomenon of a rise in an arc voltage due to deion plates, an arc current, arc voltage and voltages between the deion plates were measured for high-current air arc. The peak value of the arc voltage rose with a decrease in distance between the deion plates and electrodes. This rise resulted from the voltages between the deion plates. The voltage between the deion plates was found to consist of two voltages: (1) an arc-column voltage and (2) the voltage occuring between the arc column and the surface of the deion plates. These voltages (1) and (2) proved to be 2.3V/mm and 25V, respectively. On the basis of these results, the expression of the arc voltage affected by the arrangement of the deion plates was derived to be a function of current.
