Moulded case circuit breakers and frame circuit breakers are commonly used in circuit breaker products, but many people do not understand the difference between the two and are often hesitant to buy them. Therefore the differences between the two are highlighted here, and there are also areas to note when purchasing.

Difference 1 :

Plastic case circuit breaker using plasticized structure, which is characterized by the circuit breaker shell, frame using plastic stamping, contacts, arc extinguishing system are put into insulated chambers to prevent inter-phase short circuit, to ensure that the arc is sprayed upwards.

The circuit breaker adopts a modular structure and is divided into parts such as the frame, contact arc extinguishing system, manual operating mechanism, electric operating mechanism, intelligent controller and drawer. Each part is a completely independent component, which can be fixed with 1-2 screws during assembly, making disassembly and assembly easy and facilitating inspection and maintenance.

Difference 2 :

There is a wide range of plastic case circuit breaker products, which are characterized by compact structure, easy operation and relatively simple functions, generally configured with overcurrent release devices and instantaneous release devices.

The circuit breaker segmentation capacity is strong and functional, especially in recent years the application of single-chip computer technology, making the frame circuit breaker to high performance, easy maintenance, network development, in the segmentation capacity, the frame circuit breaker is higher than the plastic case circuit breaker

Difference 3 :

rated current of plastic-case circuit breakers is generally 630A, some new products can reach up to 1600A.

circuit breakers with a considerable rated current, generally 630A - 6300A.

In practice, circuits above 800A and circuits with special requirements for segment capacity and circuits with more functional needs generally use frame circuit breakers, and circuits below 630A generally use plastic case circuit breakers.

Difference 4.

The external contacts, interrupter chamber, striker and operating mechanism of the earth wire terminal of the plastic case circuit breaker are mounted in a plastic housing, which is generally not considered for maintenance and is suitable as a protective switch for branch circuits. There are two types of overcurrent derailleurs, electromagnetic and electronic. The common electromagnetic type of moulded case circuit breaker is a non-selective circuit breaker with only two types of protection, long delay and instantaneous. Electronic Shell circuit breakers have four protection functions: long delay, short delay, instantaneous and earth fault. Some of the newer electronic Shell circuit breakers are also available with area selective interlocking functions. Most plastic-cased circuit breakers are manually operated and some operations are also available with motors.

The circuit breakers have all components in an insulated metal frame, are normally open, can be fitted with a wide range of accessories, are easy to replace contacts and components and are mostly used for mains side switching. There are several types of overcurrent decouplers such as electromagnetic, electronic and intelligent decouplers. The circuit breaker has four levels of protection: long-delay, short-delay, instantaneous and grounding, and the protection setting value is adjusted within a certain range according to the working condition level. Both manual and electric operation are available. With the development of microelectronics technology, some intelligent circuit breakers now have area selection interlocking function, which fully ensures the agility and selectivity of the action.

Difference 5 :

In terms of external dimensions, the circuit breaker must be larger than the moulded case circuit breaker, and the current level and segmentation capacity of the circuit breaker is larger than the moulded case circuit breaker. This is an essential difference, so the applications of frame circuit breakers and plastic case circuit breakers are also different, with the frame being suitable for the upper entry line and the plastic bunker for the lower level of the frame. Those who do not know how to choose can refer to the differences explained above to choose the right product for them