Moulded case circuit breaker and frame circuit breaker are both very common products in circuit breaker products. However, many people do not fully understand the differences between the two, and they are often hesitant when purchasing. Some of the customers I face often have such troubles. Here we first understand the concepts of the two, and then understand the differences between the two, Learn about the choice of the two.

1、两者外观及安装尺寸不同：

1. They are different in appearance and installation size

首先从外观上，两者的尺寸不同，框架断路器尺寸、体积较大，塑壳断路器尺寸及体积相对较小。

First of all, from the appearance, the size of the two are different, the size and volume of the frame circuit breaker are larger, and the size and volume of the molded case circuit breaker are relatively small.

2、两者适用范围不同

2. The scope of application of the two is different

框架断路器的额度电流自400A至6300A，主要用于配电网络中，用来分配电能，保护线路和电源设备，使免受过载，欠电压，短路、单相接地等故障的危害；

The rated current of frame circuit breaker ranges from 400A to 6300A. It is mainly used in distribution network to distribute electric energy and protect lines and power supply equipment from overload, undervoltage, short circuit, single-phase grounding and other faults;

塑壳断路器的额度电流自10至800A，用于在配电线路中线路和设备发生过载、短路、欠压时，对线路和设备提供保护，也可对电动机的不频繁启动提供过载、短路、欠压保护。

The rated current of moulded case circuit breaker is from 10 to 800A, which is used to provide protection for lines and equipment in case of overload, short circuit and undervoltage in distribution lines, and to provide overload, short circuit and undervoltage protection for infrequent starting of motor.

一 级配电设备，统称为动力配电中心，它们集中安装在企业的变电站，把电能分配给不同地点的下级配电设备。这一 级设备紧靠变压器侧，故电气参数要求较高，输出电路容量也较大，一般在主配电柜中，主要元器件框架断路器。

Primary distribution equipment, collectively referred to as power distribution center, are installed in the enterprise's substation to distribute power to lower level distribution equipment in different locations. This level of equipment is close to the transformer side, so the requirements of electrical parameters are high, and the output circuit capacity is also large. Generally, in the main distribution cabinet, the main components are frame circuit breakers.

二 级配电设备，是动力配电柜和电动机控制中心的统称。动力配电柜使用在负荷比较分散、回路较少的场合；电动机控制中心用于负荷集中、回路较多的场合。它们把上一 级配电设备某一电路的电能分配给就近的负荷。这级设备应对负荷提供保护、监视和控制，一般选择使用的断路器：塑壳断路器、微断开关等。

Secondary distribution equipment is the general name of power distribution cabinet and motor control center. The power distribution cabinet is used in the situation where the load is scattered and the circuit is less; Motor control center is used in the situation of concentrated load and more circuits. They distribute the electric energy of a certain circuit of the upper level distribution equipment to the nearest load. This class of equipment shall provide protection, monitoring and control for the load. Generally, the circuit breakers used are moulded case circuit breakers, micro break switches, etc.

3、使用类别不同

3. Different use categories

塑壳断路器使用类别通常A类，在短路情况下，选择性保护无人为短延时，因而无短时耐受电流（Icw）值；

The type of MCCB is usually class A. in case of short circuit, the selective protection is short time delay, so there is no short-time withstand current (ICW);

框架断路器使用类别通常B类，在短路情况下，选择性保护有人为短延时（可调节），因而有短时耐受电流（Icw）值；

The type of frame circuit breaker is usually class B. In case of short circuit, the selective protection has artificial short time delay (adjustable), so it has short time withstand current (ICW);

具体使用，需根据负载情况，选择不同的断路器产品。

For specific use, different circuit breaker products should be selected according to the load.