Introduction to Plastic Case Circuit Breakers

Molded case circuit breakers, also known as device type circuit breakers, have all components sealed in a plastic casing. Auxiliary contacts, undervoltage releases, and shunt releases are often modular. Due to its very compact structure, molded case circuit breakers are basically impossible to repair. It mostly adopts manual operation, and large capacity can choose electric opening and closing. Due to the application of electronic overcurrent releases, molded case circuit breakers can also be divided into two types: Class A and Class B. Class B has good three-stage protection characteristics, but due to price factors, Class A products using thermal magnetic releases have a higher market share. Molded case circuit breaker is a type of circuit breaker that installs the contact, arc extinguishing chamber, release device, and operating mechanism in a plastic shell. It generally does not consider maintenance and is suitable as a protective switch for branch circuits. There are two types of overcurrent release devices: thermal magnetic and electronic. Generally, thermal magnetic molded case circuit breakers are non selective and only have two protection methods: overload long delay and short circuit instantaneous. Electronic molded case circuit breakers have four protection functions: overload long delay, short circuit short delay, short circuit instantaneous, and ground fault. Some newly launched electronic molded case circuit breakers also have a region selective interlocking function. Most molded case circuit breakers are manually operated, and there are also some with electric motor operating mechanisms.