The Difference Between Molded Case Circuit Breakers And Universal Circuit Breakers

Molded case circuit breakers and universal circuit breakers are widely used products in circuit breaker products. Many people are not very familiar with the differences between these two types of circuit breakers, so there are some unnecessary troubles when selecting circuit breakers. From the perspective of appearance and size, universal circuit breakers are larger than molded case circuit breakers. In addition to differences in external dimensions, there are also fundamental differences between the two.

A universal circuit breaker, also known as a frame circuit breaker, is a mechanical switching device that can connect, carry, and disconnect current under normal circuit conditions, as well as connect, carry, and disconnect abnormal circuit conditions within a specified time. All electrical components of a universal circuit breaker are installed in an insulated metal frame, often an open type. Multiple accessories can be installed according to requirements to improve the reliability of the universal circuit breaker. The universal circuit breaker has four stages of protection: long delay, short delay, instantaneous, and ground fault. The setting value of each protection can be adjusted within a certain range according to its housing level. The universal circuit breaker has a complete manual operation device and an electric operation device, which can achieve manual operation and electric operation for opening and closing.

Molded case circuit breaker, also known as device type circuit breaker, uses plastic insulation as the outer shell of the device, which can effectively isolate the conductors and the grounded metal part. All parts are sealed in plastic shells, and due to their relatively compact structure, plastic shell circuit breakers are generally not considered for maintenance. Molded case circuit breakers can play a role in control and protection in distribution systems, integrating control and multiple protection functions. In addition to being able to contact and disconnect power lines, it can also protect circuits and electrical equipment from the hazards of short circuits, overvoltage, single-phase grounding, and other faults. Generally, molded case circuit breakers only have two protection functions: overload long delay and short-circuit instantaneous. Another type of molded case circuit breaker that uses an electronic release unit has four protection functions: overload long delay, short circuit short delay, short circuit instantaneous, and ground fault.

 

Through the above description, everyone can clearly understand that both universal circuit breakers and molded case circuit breakers have the basic characteristics of circuit breakers. There is a significant difference in their usage. Universal circuit breakers are mainly used for upper level incoming lines as main switches, while molded case circuit breakers are used for lower level frames as terminal distribution. The difference in usage between the two types of circuit breakers is mainly due to their different current levels and breaking capabilities. Universal circuit breakers are superior to plastic case circuit breakers in these aspects, which is also the fundamental difference.
In terms of rated current, universal circuit breakers can generally operate between 200-6300A, while molded case circuit breakers are mostly below 600A.

In terms of release settings, universal circuit breakers are easy to obtain additional functions and can be equipped with multiple types of releases to enrich their functions and adapt to different protection requirements. However, most molded case circuit breakers only have one of the three options: overcurrent, voltage loss, and shunt.

From the perspective of repairability, due to the modular structure design of the universal circuit breaker, the disassembly of components is convenient and easy to maintain. However, due to the compact structure of the molded case circuit breaker, electrical components are installed inside the shell, which brings great difficulties to maintenance. Therefore, molded case circuit breakers generally do not consider maintenance.