1. Circuit breaker: a mechanical switching device that can connect, carry and disconnect the current under normal circuit conditions and also connect, carry and disconnect the current for a certain time under specified abnormal circuit (such as short circuit).

2、塑壳式断路器：具有一个用模压绝缘材料制成的外壳作为断路器整体部件的断路器。

2. Molded case circuit breaker: a circuit breaker with a shell made of molded insulating material as an integral part of the circuit breaker.

3、空气断路器：触头在大气压力的空气中断开和闭合的断路器。

3. Air circuit breaker: a circuit breaker whose contact is interrupted and closed by air at atmospheric pressure.

4、真空断路器：触头在高真空管中断开和闭合的断路器。

4. Vacuum circuit breaker: a circuit breaker whose contact interrupts opening and closing in high vacuum tube.

因为“塑壳式断路器”一般使用空气作为灭弧介质，因此有空气开关的俗称，但空气开关的说法其实并不严谨，开关与断路器是不同的两个概念。

Because the "molded case circuit breaker" generally uses air as the arc extinguishing medium, it is commonly known as air switch, but the statement of air switch is not rigorous. Switch and circuit breaker are two different concepts.

空开与塑壳的主要区别：

Main differences between air switch and plastic shell:

1、塑壳断路器也是“空气断路器”。常用的空气断路器有框架式断路器和塑壳断路器两种。前者的容量大，额定开断电流也大，体积也大，所以没有塑料外壳，断路器的各部分零件装在一个钢框架上。后者的容量相对较小，额定开断电流也小一些，所以体积也小，整个断路器采用塑料外壳保护。一般框架式断路器用于电流较大的电源回路上，而塑壳断路器用于负荷回路上。

1. Molded case circuit breakers are also "air circuit breakers". There are two kinds of commonly used air circuit breakers: frame circuit breaker and molded case circuit breaker. The former has large capacity, large rated breaking current and large volume, so there is no plastic shell, and all parts of the circuit breaker are installed on a steel frame. The capacity of the latter is relatively small, and the rated breaking current is also small, so the volume is also small. The whole circuit breaker is protected by plastic shell. Generally, frame circuit breaker is used for power circuit with large current, while molded case circuit breaker is used for load circuit.

2、空气开关一般在小电流电路中主要起“隔离”和“保护装置”的作用，也叫自动开关，也叫空气断路器；

2. Air switch generally plays the role of "isolation" and "protection device" in small current circuit, also known as automatic switch and air circuit breaker;

3、断路器有很好的灭弧能力，在电路短路大电流情况下，自动跳闸；在高电压、大电流电路中，常用作停电、送电，接通、断开负荷的操作电器；

3. The circuit breaker has good arc extinguishing ability and can trip automatically under the condition of short circuit and large current; In high voltage and high current circuits, it is often used as an operating appliance for power failure, power transmission, connecting and disconnecting load;

4、电流等级：塑壳断路器一般为630A以下，空气断路器一般为630A以上，微型断路器一般为63A以下；

4. Current level: molded case circuit breaker is generally below 630A, air circuit breaker is generally above 630A, and miniature circuit breaker is generally below 63A;

5、电压等级的区别：一般空气开关合用的电压等级为500V以下,而断路器通常可以合用于220V以上的各电压等级；

5. Difference of voltage level: generally, the voltage level shared by air switch is less than 500V, while circuit breaker can usually be used for each voltage level above 220V;

6、遮断电流的能力不同：一般断路器能承受的负荷及短路电流更大些；

6. The ability of interrupting current is different: the general circuit breaker can bear more load and short-circuit current;

7、灭弧介质和方式的区别：断路器的灭弧介质和方式不但有空气断路器,还有真空断路器,多油断路器,少油断路器,六氟化硫断路器等；

7. Difference between arc extinguishing medium and mode: the arc extinguishing medium and mode of circuit breaker include not only air circuit breaker, but also vacuum circuit breaker, multi oil circuit breaker, low oil circuit breaker, sulfur hexafluoride circuit breaker, etc;

8、配套设备的区别：一般相对于空开来讲断路器的丈量,逻辑及执行部门的机构所配套的设备更复杂一些。

8. Difference of supporting equipment: Generally speaking, the measurement of circuit breaker and the supporting equipment of logic and executive department are more complex than that of air.