Abstract: Aiming at the phenomenon that the motor circuit breaker trips when the combined air conditioner unit is powered on and the motor starts. Firstly, determine the cause of the circuit breaker tripping. Through the analysis of the cause of the circuit breaker tripping, analyze the influence of different power fixed-frequency motor starting methods on the starting current. Starting from the analysis of the motor parameters, the circuit breaker characteristic current is analyzed. The analysis of the current curve when the high-speed motor starts at high speed, draws the root cause of the circuit breaker tripping, and gives an effective conclusion on how to select the circuit breaker reasonably to avoid the circuit breaker tripping when the motor starts. For this kind of electrical problems, it is necessary to pay attention to the abnormal component test, which requires systematic analysis. It is not possible to analyze a certain component separately, and pay attention to the interrelationship.

Key words: Circuit breaker, Motor, Overcurrent protection, Trip