Gas flow and composition effects on arc motion in current limiting circuit breakers

Arc motion in low voltage (240 VAC) high current (10³-10⁴ A) current limiting circuit breakers is dominated by arc root mobility. This is strongly affected by the gas flow and gas composition in the contact region, but there is little experimental data on these effects. New pressure and spectral data measurement during arc movement are presented using a flexible test apparatus and an arc imaging system. These measurements are used to investigate gas flow characteristics in the arc chamber. The chemical and physical phenomena occurring during the arc motion are discussed. The combination of optical and spectral data provides new insight into the arc motion. Also studied are the influences of arc chamber material, contact material, and contact opening speed. These data are used to improve arc control for a low contact opening velocity of 1 ms^-1