Introduction was made to the appearance of air circuit breaker less voltage tripper, installation position and other technological improvement measures, with the structure and component drawings of improved component of the circuit breaker given.

The paper introduces the Mechanism and testing results of Puffer Arc Quenching technique, Configuration of Quenching Chamber by using this new approach, and new pressure trip based on gas pressure produced by wall ablation, which is benefit to improve the interrupting performance of Low-Voltage Circuit Breakers.