Technical principle of molded case circuit breaker

Molded case circuit breaker is also called device type circuit breaker. All parts are sealed in the plastic housing. Auxiliary contacts, undervoltage releases, shunt releases, etc. are mostly modular. Due to its compact structure, the molded case circuit breaker can hardly be overhauled. Most of them are manually operated, and electric opening and closing can be selected for large capacity. Due to the application of electronic over-current release, molded case circuit breakers can also be divided into Class A and Class B. Class B has good three-stage protection characteristics. However, due to price factors, Class A products with thermal magnetic release have a higher market share. Molded case circuit breaker is used to install contacts, arc extinguishing chambers, releases, operating mechanisms, etc. in a plastic housing. Generally, maintenance is not considered. It is suitable for branch protection switches. There are two types of over-current releases: thermal magnetic release and electronic release. Generally, thermal magnetic molded case circuit breaker is a non selective circuit breaker. There are only two types of protection: overload long delay and short circuit instantaneous. Electronic molded case circuit breaker has overload long delay, short circuit short delay Short circuit instantaneous and ground fault protection functions. Some new products of electronic molded case circuit breakers also have the function of regional selective interlocking. Most molded case circuit breakers are manually operated, and some are equipped with motor operating mechanism.