Moulded case circuit breakers, also known as device circuit breakers, have all internal components encapsulated in a plastic housing, modular internal components and a powerful segmentation and isolation protection capability. Next, we will describe the main features and functions of moulded case circuit breakers.

Moulded case circuit breaker functions.

1、Segmentation capacity

There are two indicators for the segmentation capacity of circuit breakers: the rated limit segmentation capacity and the rated operating short-circuit segmentation capacity. iCS, as a characteristic parameter of circuit breakers, does not only consider the segmentation capacity of the circuit breaker, but serves as an indicator that the circuit breaker can disconnect multiple short-circuit currents after normal operation. The ICU must be sufficient for a moulded case circuit breaker to cut off the circuit breaker's function. As a rule, a moulded case circuit breaker with an ICS greater than 25% is considered to be satisfactory. Therefore, the demand on the distribution system is not so high that the ICU is sufficient to be considered.

2、Current limiting breaking capacity

When the circuit breaker is short-circuited, the contacts open rapidly to produce an arc, which corresponds to a rapidly increasing arc resistance in the line, limiting the increase in fault current. The shorter the breaker time, the closer the Ics is to the Icu, the better the current limiting effect, which can greatly reduce the adverse effects of electromagnetic effects on electrical equipment caused by short circuit current and prolong the service life of the breaker.

The role of the molded case circuit breaker.

1、Short circuit protection

When the circuit is short-circuited, the armature of the overcurrent detriggers suck and, so that the detriggering mechanism through the action, the main contacts disconnect the main circuit, so that this important part of the main problem analysis circuit disconnect.

2、Overload protection

When the load current exceeds the limit current of the equipment, the protection device will cut off the current for a period of time. When the short-term overcurrent, the protection device should not act.

3、Isolation function

Refers to the circuit breaker open after the leakage will not cause excessive harm to human body and equipment, the circuit breaker many times after the operation of the switch performance decreases, leakage will also increase. In a harsh environment, leakage current leakage of 300mA or more for more than two hours will cause short-circuit fire damage to the insulation.

4、Leakage protection

There are two types of electricity in the building:thermal magnetic and electronic. At present, electronic leakage is the mainstream, the advantage is the small size. High precision and sensitivity, but poor anti-interference ability. When the leakage current reaches a certain value, the execution circuit receives the induced voltage signal and drives the switch contacts to output the leakage protection signal, so that the decoupler cuts off the current.