저압 배선용차단기 설계인자에 따른 절연회복특성

Abstract

For protecting loads from the over-current, the Molded Case Circuit Breaker (MCCB) is one of the most widely used devices in low power system. In the process of the over-current interruption, hot-gas is generated in the inside of the contact system in the MCCB. The hot-gas and the structure of arc quenching unit makes the Dielectric Recovery Voltage (DRV) decreased under the Recovery Voltage(RV) of system. The DRV is the dielectric recovery strength between electrodes. The RV is the recovery voltage applied from power supply. When the DRV is reduced below the RV, the re-ignition occurs and leads to interruption failure. To optimize the structure of MCCB, it is necessary to analyze the dielectric recovery characteristics affected by design parameters. In this paper, the dielectric recovery characteristics according to design parameters of the MCCB is investigated. It can be analyzed by measuring the DRV between electrodes of arc quenching unit. To find out the effect of design parameters on the dielectric recovery voltage, we implements experiments which change conditions of the grids and vent of MCCB. Consequently, the remained hot-gas plays an important role in the dielectric recovery strength and the fast emission of the hot-gas is the key to increase the dielectric recovery strength in the initial period. Also, the grids eliminates the hot-gas through cooling and adsorption.