Arc Extinction Structure of Air Circuit Breaker for Improvement of Direct Current Breaking Performance

Air Circuit Breaker (ACB) is an electric control device that can interrupt the abnormal current in low voltage (less than 1,000Vac or 1,500Vdc) distribution line. In general, abnormal current means short-circuit, over-load and grounding current and causes serious damage on electric devices in electric system. Therefore, the circuit breaker shall break a fault current quickly and safely to prevent accidents in the electric system. Nowadays, DC circuit breaker gains much attentions in the world because it can protect the electric devices in photovoltaic (PV) facilities, and energy storage system (ESS). In particular, circuit breakers (or switch-disconnectors) in PV facilities usually break (or switch off) small current after sunset. So, international electrotechnical commission (IEC) standards include not only large current interruption performance but also small current interruption. In this paper, we consider relation between the magnetic field and the arc driving force when ACB breaks a fault current, and design the arc extinction structure which for improvement of small current breaking performance. For design verification, we perform electromagnetic field analysis using CAE, and experimental test based on IEC standards.