A study on characteristics and methods of extinguishing arc in low voltage direct current system

A low voltage DC(Direct Current) circuit breaker is an electric control device that interrupts the abnormal currents which result from the over-loads or short-circuits in a low voltage(less than 1,500Vdc) distribution line. Recently, higher current breaking performance has become crucial in providing the reliability for the modern devices requiring small scale and high performance. When a short circuit occurs, a fault current flows between contacts of DC circuit breaker even though they are separated by the protective control system. Arc voltage between contacts of circuit breaker should generate as high as possible during breaking phase. High arc voltage could lead the main circuit to zero arc current so that arc plasma is eliminated. Based on this behavior, arc extinction system of a circuit breaker should be designed for increasing arc voltage during breaking period of the current. Since DC does not have current zero point, it can be more difficult and important to secure the breaking performance. There are conventional methods that are widely known as arc extinction methods and most of them involve method for increasing arc voltage. In this paper, experiments and CAE analysis were carried out to find out the criteria of the arc extinction and to verify the validity of methods of extinguishing an electric arc. Copyright © The Korean Institute of Electrical Engineers.