Case and frame circuit breakers are commonly used in circuit breaker products, but many people don't quite understand the difference between the two and tend to raise their hands when buying them. Some of the customers I deal with have such troubles. Therefore, based on this problem, I consulted three senior engineers in the factory and summarised their usual buying tips. This section describes the differences between moulded case circuit breakers and frame circuit breakers, and what to look for when choosing one.

High segmentation capability of circuit breakers

The plasticized structure of the case circuit breaker is characterized by the fact that the breaker shell and frame are made of plastic stamping, and the contacts and arc extinguishing system are put into insulated chambers to prevent short-circuiting between phases and ensure that the arc is ejected upwards while the circuit breaker adopts a modular structure and is divided into parts such as frame, contact arc extinguishing system, manual operating mechanism, electric operating mechanism, intelligent controller and drawer. Each part is a completely independent component and can be fixed with 1-2 screws when assembled, making disassembly and assembly easy and facilitating inspection and maintenance.

A wide range of molded case circuit breaker products, which are characterized by compact structure, easy operation, relatively simple functions, generally configured with overcurrent decoupler and instantaneous decoupler, circuit breakers are fully functional, especially in recent years, the application of single-chip computer technology, frame

Under the rated current, plastic case circuit breakers are generally below 630A (some new products are 1600A ), but the rated current of the circuit breaker is 630A-6300A ), quite large, for example, the company manufactured DW15, DW16, DW17 series of circuit breakers In addition, in terms of segmentation capacity, frame relay circuit breakers than plastic box circuit breakers high.

In practice, for circuits above 800A and circuits with special requirements for segment capacity and circuits requiring more versatility, frame circuit breakers are generally used, while circuits below 630A generally use plastic case circuit breakers.