Arc Movement Inside an AC/DC Circuit Breaker Working With a Novel Method of Arc Guiding: Part II—Optical Imaging Method and Numerical Analysis

摘要

This paper aims at understanding the design concept and behavior of the ionized gases inside a new electrical contactor. The switching device is designed for ac and dc operations up to 3.5 kV and nominal currents up to 800 A. The contactor consists of five electrodes: two anodes, two cathodes, and a moving electrode or bridge which works as an anode and a cathode simultaneously. In order to increase the safety, the electrical contactor includes two contact points. The line current can be diverted into an arc between the electrode and the bridge and an arc between the runner electrodes. The movement of the ionized gases is controlled by two permanent magnets and two coils installed near the electrodes. The arc plasma itself feeds the coils with current. The arc plasma velocity increases if more current is allocated in the arc plasma. The dynamics of ionized gases in the contactor is analyzed using two optical methods, viz., optical imaging method and high-speed camera (HSC). The optical imaging software has been developed to generate dynamic images of the high-speed ionized gases at a rate of 50 000 frames/s. The results of this method have been compared with those obtained using an HSC. A transient numerical model has been developed to simulate the arc plasma inside the main runner for the case of dc current. The properties of the air plasma are considered variable with temperature and pressure. The calculation shows the position and temperature of the arc plasma as a function of time.