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MCB–Miniature Circuit Breaker

Publish Time: 2022-07-25 11:00:25     Author: DELIXI

Miniature Circuit Breaker, also known as Micro Circuit Breaker, is suitable for overload and short Circuit protection of ac 50/60Hz rated voltage 230/400V, rated current up to 63A. It can also be used for infrequent operation conversion of the line under normal conditions. Miniature circuit breakers are mainly used in industrial, commercial, high-rise and civil residential and other places.

Working Conditions

1. The upper limit of ambient air temperature shall not exceed +40℃, and the lower limit shall not be less than -5℃, and the average temperature of 24h shall not exceed +35℃;

Note 1: the user shall declare to the manufacturer when placing an order for the working conditions whose lower limit is -10℃ or -25℃;

Note 2: If the upper limit exceeds +40℃ or the lower limit is below -25℃, the user should consult with the manufacturer.

2. The altitude of the installation site shall not exceed 2000m;

3. The relative humidity of the atmosphere should not exceed 50% when the ambient air temperature is +40℃, and a higher relative humidity can be allowed at a lower temperature, such as 90% when the temperature is +20℃. Appropriate measures should be taken for the occasional condensation caused by temperature changes;

4. Pollution level: Level 2;

5, installation type: class ⅱ and class ⅲ;

6. The external magnetic field of the installation site should not exceed 5 times of the earth magnetic field in any direction;

7, general vertical installation, any direction tolerance of 2°;

Miniature circuit breaker

Miniature circuit breaker (4 sheets)

8, there should be no significant impact and vibration at the installation place.


1, Rated working voltage (Ue) : AC 230V/400V (1P), 400V (2P, 3P, 4P).

2, Rated insulation voltage (Ui) : 600V.

3, Rated impact withstand voltage (Uimp) : 4KV

4, Rated current (In) : 1A, 3A, 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A.

5, Rated short circuit breaking capacity (Icn) : 6A-40A: 6000A, 50A-63A: 4500A.

6, Short circuit breaking capacity (Ics) : 6A-40A: 6000A, 50A-63A: 4500A.

7. Number of poles: a. single pole (1P); B. two poles (2P); C. Three poles (3P); D. quadrupole (4P).

8, Instantaneous trip type: a.C type (5ln-10ln); B.D type (10ln-20ln).

9, The reference ambient temperature: 30℃.

10, Grid distance (mm) : 6A-40A: 50mm, 50A-63A: 45 mm.

11. Protection grade of shell: IP20.

12, Life: a. Electrical life: not less than 4000 times; B. Mechanical life: not less than 20000 times.

Appliance Range

Miniature circuit breakers have the advantages of advanced structure, reliable performance, strong breaking ability, beautiful and compact appearance, and are mainly used in places with AC 50HZ or 60HZ, rated voltage below 400V and rated operating current below 63A. For office buildings, residential and similar buildings lighting, power distribution lines and equipment overload and short circuit protection, can also be used for infrequent line on and off operation and conversion. Mainly used in industrial, commercial, high-rise and residential and other places.


The mini-circuit breaker consists of the following main parts:

1. Separable contact connection. It consists of a fixed contact and a movable contact.

2. A device composed of a metal cylinder or an insulating cylinder, wherein a separable contact connection and arc extinguishing device and a transmission device are installed.

3, Drive the contact transmission device.

4. Arc extinguishing equipment.

Commonly used small circuit breakers break the circuit is to use mechanical method to separate the small circuit breakers moving contact and fixed contact. The opposite mechanical movement is used to close the moving contact and the fixed contact. During the operation of switching on and off the load circuit, an electric arc will be generated between the fixed contact and the moving contact. The arc produced by the opening process is much more serious than the closing process. When the breaking current is very large, especially when the breaking short circuit, the arc is very large, the circuit is often very difficult to disconnect.


1, High rated short-circuit breaking capacity, part of the rated current grade can reach more than 10KA.

2, Double connection function, can easily connect the standard busbar and soft wire.

3, Combined terminal with finger contact protection, higher safety.

4, With energy storage mechanism operation, fast contact closure, overcome the adverse impact of manual operation handle speed, improve the service life of the product.

5, A variety of accessories to choose from, and modular, flexible combination, user installation is very convenient.

6. The shell and some functional parts are made of high flame retardant, high temperature resistant and impact resistant plastic imported from abroad.

7, High current limiting coefficient, superior performance/price ratio.


1, The selection of ordinary leakage circuit breaker

Choose leakage circuit breaker to follow the following principles:

(1) The rated voltage and current of the circuit breaker should be greater than or equal to the normal working voltage and current of the line equipment;

(2) The leakage current protected by the line should be less than or equal to the specified leakage protection current of the circuit breaker;

(3) The limit on/off capacity of the circuit breaker should be greater than or equal to the maximum short-circuit current; 

(4) The rated current of overload trip is greater than or equal to the maximum load current of the line; 

(5) It has a short breaking reaction time, which can protect the line and equipment. 

2, Four pole circuit breaker selection

Whether to choose a quadrupole circuit breaker can follow the following principles:

(1) In accordance with IEC465.1.5, the switching circuit breaker between the normal supply and the standby generator shall use a quadrupole circuit breaker; 

(2) Double power supply conversion circuit breaker with leakage protection should be four-pole circuit breaker. Two upper circuit breakers with leakage protection, the lower power conversion circuit breakers should use four-pole circuit breakers;

(3) Four-pole circuit breaker should be used for power switching between two different grounding systems; 

(4) The tn-C system is strictly forbidden to use quadrupole circuit breaker; 

(5)TN-S and TN-C-S systems generally do not need to set quadrupole circuit breakers. However, some special conditions of TN-S system (serious three-phase unbalance, high zero sequence harmonic content) need to be further studied. 

(6) The power input circuit breaker of TT system should adopt quadrupole circuit breaker; 

(7) Four-pole circuit breaker should be used when neutral line is drawn out in IT system.

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