抄録
In a molded-case circuit breaker (MCCB), an arc column is not always kept to burn inside deion plates but several times is shorten in the narrow area between electrodes. This unstable arc behavior brings several sudden drops in the arc voltage and stops for a time the current limiting process. In this paper, three different methods are proposed to control the unstable arc motion in the MCCB and their effects on the current limiting performance of the MCCB is experimentally discussed.
An arc-runner is mounted on the moving contact to keep the arc column inside all deion plates. A pertition wall is inserted between arc chamber and mechanical operation section to control high temperature air flow. The moving contact is coated with epoxy resin to prevent the shortcut of the arc column. It is found out from experiments that they are useful to repress the unstable arc motion and to improve the current limiting performance of the MCCB. For example, the arcing time is reduced to 80% of that in the normal MCCB by each method.
