The difference between molded case circuit breakers and miniature circuit breakers

The difference between molded case circuit breakers and miniature circuit breakers


Molded Case Circuit Breaker (MCCB for short) is mainly used to provide protection for overload and short circuit in low voltage distribution system and motor protection circuit. Because of its reliability and stability, it has become a widely used product in industry. Miniature circuit breaker (abbreviated as MCB) is also a circuit breaker product with a wide range of use and quantity, and is mainly used for providing protection for building electrical terminal equipment. Because both belong to the circuit breaker and the molded case circuit breakers are used for switching the small capacity, it is very realistic and important to understand the difference between the two and choose the right product. Here’s a brief explanation.

Miniature circuit breaker (MCB)
Miniature circuit breaker (MCB)

Let me talk about the basic similarities, because both belong to the circuit breakers, and all need to comply with some basic product standards and have the same working principle.

After that, the difference between the two is as follows:
1 different electrical parameters;
2 different mechanical parameters;
3. Use different working environment.

In addition, from the purchase point of view, specifically the difference between the two.

Current level

MCCB(Molded case circuit breakers) have a current rating of up to 2000A, while miniature circuit breakers have a maximum current rating of less than 125A. Due to the difference in capacity between the two, the effective area of MCCB(molded case circuit breakers) is also larger than that of MCB(miniature circuit breakers). At the same time, the wires that are connected are relatively thick and can reach more than 35 square meters, and the MCB(miniature circuit breakers) are only suitable for conductors less than 10 square meters. . So for the indoor situation, the larger room is more suitable to choose molded case circuit breakers(MCCB).

Installation method

Molded case circuit breakers(MCCB) are mainly installed with screws, which are easy to compress, have good contact, and have stable operation. The MCB(miniature circuit breaker) is mainly installed through the guide rails, sometimes due to insufficient torque to cause poor contact. Because of the different installation methods of the two, the installation of the molded case circuit breaker is more stable than the miniature circuit breaker and the difficulty is even lower.

Operation and life

In operation, the MCCB protects the convection and the short circuit with two devices respectively. The overcurrent protection action value can be manually adjusted, which is convenient and rapid. The miniature circuit breaker has a common device for over-current and short-circuit, and the current is not adjustable, resulting in many problems that cannot be solved. Molded case circuit breakers have a large distance between them, arc extinguishing covers, and arc extinguishing ability, can withstand greater short-circuit currents, and are less likely to cause phase-to-phase short circuits, and thus have a longer service life than miniature circuit breakers.


In this regard, the MCCB(molded case circuit breaker) is more prominent, and it is better than the MCB(miniature circuit breaker) in terms of flexibility of setting. The over-current and short-circuit protection devices of the MCCB are independent, and the over-current protection operation value can also be flexibly adjusted. The over-current protection and short-circuit protection of miniature circuit breakers(MCB) are a unified device, and there are certain deficiencies in the adjustment flexibility.

According to the above situation, it seems that the MCCB(miniature circuit breaker) is in the downwind, but in fact, for certain times, it is still necessary to select a MCB(miniature circuit breaker). For example, when it is necessary to improve the safety of the line, the MCB(miniature circuit breaker) has a high sensitivity of action and a fast breaking action, which is more conducive to the protection of lines and electrical appliances.

This shows that both have their own advantages and suitable for use, the key is to fully understand the difference between molded case circuit breakers and miniature circuit breakers, and choose according to their own needs.




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