Characteristics of Arc Voltage for High-Current Air Arc under Arrangement of Deion Plates and Approach to Improving Availability of the Plates

Abstract

In this study, (i) effect of deion plates on arc voltage and (ii) appropriate arrangement of the plates were investigated in order to develop a design guide of a circuit breaker which is able to interrupt fault current (> several kA). As for evaluation (i), improved effect on arc voltage under arrangement of the plates were evaluated quantitatively in association between arc voltage and the design factors which are current, arc length, internal pressure and number of the used plates. As the result, it was found that arc voltage rises 19.2V by number of split arc between the plates and electrical field in arc rises about 3V/mm under high internal pressure above 0.2MPa-g. Experimental formula constituted by the design factors for estimation of arc voltage was developed on the basis of the improved effect on the voltage. Since the formula is able to estimate actual arc voltage with a margin of error within about 7%, it would be provided as effective guidelines to design arc extinguishing chambers. As for evaluation (ii), dependences of the availability of used plates on electromagnetic force to drive arc were evaluated. As the result, it is found that the plates are used effectively by exerting above a certain electromagnetic force (e. g., above 5N in case of 5kA) on the arc between the electrode and the plate. Therefore, the improvement of magnetic design near the electrodes, especially the movable electrode, or the arranging enough space to drive the arc between the electrode and the plate would be improved availability of the used plates.