How does a Mini circuit breaker work?

Micro circuit breakers are an indispensable device in many homes. Do you know how to choose the right MCB? What is the structure and function of the MCB?

• What is the structure of MCB?

• What is the principle of a miniature circuit breaker?

• How to choose the right MCB?

What is the structure of a MCB?

Miniature circuit breaker(MCB) is a kind of circuit breaker with small capacity and plastic case which is very compact. It is a branch of low voltage circuit breaker and has become a large category of terminal appliances. Micro circuit breakers are used to protect electrical appliances, mainly to protect circuits and equipment safety. When the circuit or electrical equipment overload, short circuit and other faults, the tripping device should be able to timely action, reliable cut off the circuit; When the circuit or electrical equipment is in normal condition, the main contact should be able to connect the circuit reliably, and the release should not fail. The main fault modes of MCB are operation fault, misoperation fault, and rejection fault. The MCB is generally composed of operating mechanism, contact, protection device (all kinds of trip), arc extinguishing system, etc.

What is the principle of a miniature circuit breaker?

The overload protection function of the MCB is based on the principle that the bimetallic sheet bends regularly with increasing temperature. When the mini-circuit breaker is in normal operation after closing, due to the internal bimetallic sheet being heated by a certain current, the two metals are bent due to the different coefficient of thermal expansion. When the normal current passes through, the bending Angle of the bimetal sheet is not large, and the thrust is not enough to trip the tripping mechanism. When the line is generally overloaded, the bimetallic sheet bending angle is large, and the tripping mechanism is touched. The lever with sufficient thrust to push the trip mechanism enables the MCB to trip for overload protection. Bimetallics differ according to the amount of electricity flowing through them. When the circuit is generally overloaded, the trip time of the circuit breaker is usually longer due to the low overload current.

How to choose the right MCB?

1. The rated working voltage of the MCB is greater than or equal to the rated line voltage.

2. The rated current of the MCB must be greater than or equal to the line calculated load current.

3. The rated short-circuit breaking capability of the MCB is greater than or equal to the maximum short-circuit current that may occur in the circuit.

4. The setting current of the instantaneous MCB trip is less than 0.8 times of the single-phase ground short circuit current at the end of the line.

5. Consider the coordination between the on-off capability of short delay short circuit and the delay protection level.

If you are looking for Mini circuit breaker with good quality and reasonable price, Zhejiang Chinehow Technology Co., Ltd. can provide you with the best.