Molded case circuit breakers are a type of low-voltage circuit breaker, also known as device-type circuit breakers. This type of circuit breaker seals all parts in a plastic shell, and auxiliary contacts, undervoltage releases, and shunt releases are mostly modular in design. Due to its very compact structure, molded case circuit breakers are basically unable to be internally repaired, and most of them are manually operated. For large-capacity models, electric separation and closing can be selected.
In addition, according to the application of electronic overcurrent releases, molded case circuit breakers can be further divided into Class A and Class B. Class A molded case circuit breakers usually use thermal magnetic releases, which are non-selective circuit breakers and mainly provide two protection modes: long overload delay and short circuit instantaneous; while Class B molded case circuit breakers have better three-stage protection characteristics (long overload delay, short short circuit delay, short circuit instantaneous), and some products also have ground fault protection functions, and even have regional selective interlocking functions. However, due to price factors, Class A products using thermal magnetic releases usually have a higher market share.