MCCB can cut off the current automatically when the current exceeds the trip setting. Plastic shell refers to the use of plastic insulator as the shell of the device, which is used to isolate the conductor and grounding metal parts. Moulded case circuit breakers usually contain thermal magnetic trip units, while large moulded case circuit breakers are equipped with solid state trip sensors. The release unit is divided into thermal magnetic release and electronic release.

塑殼斷路器也被稱為裝置式斷路器，所有的零件都密封于塑料外殼中，輔助觸點(diǎn)，欠電壓脫扣器以及分勵脫扣器等多采用模塊化。由于結(jié)構(gòu)非常緊湊，塑殼斷路器基本無法檢修。

Moulded case circuit breaker is also called device circuit breaker. All parts are sealed in plastic shell. Auxiliary contact, undervoltage release and shunt release are mostly modularized. Due to its compact structure, moulded case circuit breaker can hardly be repaired.

其多采用手動操作，大容量可選擇電動分合。由于電子式過電流脫扣器的應(yīng)用，塑殼斷路器也可分為A類和B類兩種，B類具有良好的三段保護(hù)特性，但由于價格因素，采用熱磁式脫扣器的A類產(chǎn)品的市場占有率更高。

Most of them are operated by hand, and large capacity can choose electric on-off. Due to the application of electronic over-current release, moulded case circuit breaker can also be divided into class A and class B. class B has good three section protection characteristics. However, due to the price factor, the market share of class a products with thermal magnetic release is higher.

塑殼斷路器是將觸頭、滅弧室、脫扣器和操作機(jī)構(gòu)等都裝在一個塑料外殼內(nèi)，一般不考慮維修，適用于作支路的保護(hù)開關(guān)，過電流脫扣器有熱磁式和電子式兩種，一般熱磁式塑殼斷路器為非選擇性斷路器，僅有過載長延時及短路瞬時兩種保護(hù)方式。

Moulded case circuit breaker (MCCB) is a kind of protective switch for branch circuit. The contact, arc extinguishing chamber, release and operating mechanism are all installed in a plastic shell. Generally, maintenance is not considered. There are two kinds of over-current release: thermal magnetic type and electronic type. Generally, thermal magnetic MCCB is a non selective circuit breaker, which only has two kinds of protection methods: overload long delay and short-circuit instantaneous.

電子式塑殼斷路器有過載長延時、短路短延時、短路瞬時和接地故障四種保護(hù)功能。部分電子式塑殼斷路器新推出的產(chǎn)品還帶有區(qū)域選擇性連鎖功能。大多數(shù)塑殼斷路器為手動操作，也有部分帶電動機(jī)操作機(jī)構(gòu)。

Electronic moulded case circuit breaker has four protection functions: overload long delay, short circuit short delay, short circuit instantaneous and grounding fault. Some new products of electronic moulded case circuit breaker also have regional selective interlocking function. Most moulded case circuit breakers are operated manually, and some are equipped with motor operating mechanism.