工作原理
Working principle
低压断路器的主触点是靠手动操作或电动合闸的。主触点闭合后，自由脱扣机构将主触点锁在合闸位置上。过电流脱扣器的线圈和热脱扣器的热元件与主电路串联，欠电压脱扣器的线圈和电源并联。
The main contacts of low voltage circuit breakers are operated by manual operation or by electric switching. After the main contact is closed, the free tripping mechanism locks the main contact on the closing position. The coil of the over current release and the thermal element of the thermal release are connected in series with the main circuit, and the coil of the undervoltage release is parallel to the power supply.
当电路发生短路或严重过载时，过电流脱扣器的衔铁吸合，使自由脱扣机构动作，主触点断开主电路。
When the circuit is short circuited or seriously overloaded, the armature of the over current release is pulled to make the free tripping mechanism act, and the main contact disconnects the main circuit.
当电路过载时，热脱扣器的热元件发热使双金属片上弯曲，推动自由脱扣机构动作，主触点断开主电路。
When the circuit is overloaded, the heating element of the thermal release is bent on the bimetal sheet to drive the free tripping mechanism, and the main contact disconnects the main circuit.
当电路欠电压时，欠电压脱扣器的衔铁释放，也使自由脱扣机构动作，主触点断开主电路。
When the circuit is under voltage, the release of the armature of the undervoltage release also causes the free tripping mechanism to act, and the main contact disconnects the main circuit.
当按下分励脱扣按钮时，分励脱扣器衔铁吸合，使自由脱扣机构动作，主触点断开主电路。
When the split release button is pressed, the armature release of the split release lever moves the free tripping mechanism, and the main contact disconnects the main circuit.
分类
classification
低压断路器是按熄灭介质的不同分类的，利用空气作为灭弧介质的断路器，称之为空气断路器（空气开关）；利用惰性气体作为灭弧介质的断路器，称之为惰性气体断路器（惰性气体开关）；利用油作为灭弧介质的断路器，称之为油断路器（油开关）。
Low voltage circuit breaker is a circuit breaker based on the extinguishing medium, using air as an arc extinguishing medium, known as air circuit breaker (air switch); a circuit breaker using inert gas as an arc extinguishing medium, is called an inert gas circuit breaker (inert gas switch), and oil is used as a circuit breaker for arc extinguishing medium. It is the oil circuit breaker (oil switch).