Knowledge of switching appliances: learn the basic principles of miniature circuit breakers

Datetime: 12/12/2022 2:54:00 PM   Visit: 308

For ordinary people, the term miniature circuit breaker is relatively unfamiliar, but it plays a vital role in life. The circuits we usually use, if we want to ensure safety, we cannot do without them. So how exactly does a miniature circuit breaker work? What is a miniature circuit breaker, its advantages, and installation methods, let's take a look at the miniature circuit breaker below.

iniature Circuit Breakers L7 2P(new type)

How Miniature Circuit Breakers Work
After the miniature circuit breaker is closed and under normal working conditions, the internal bimetal sheet will generate heat due to a certain current passing through it, and the thermal expansion coefficients of the two sheets of metal are different, resulting in bending. When the line reaches the overload current, the bimetal sheet bends at a larger angle and pushes the trip mechanism, so that the miniature circuit breaker trips and plays the role of overload protection.
The overload protection function of the miniature circuit breaker is realized by using the principle that the bimetal bends directionally and regularly as the temperature rises. Depending on the amount of current flowing through the miniature circuit breaker, the degree of bending of the bimetal is also different. When the line is generally overloaded, the tripping time of the circuit breaker is generally longer because the overload current is not too large.

Installation method of miniature circuit breaker
Generally speaking, the rated breaking capacity of the miniature circuit breaker is measured when the upper terminal enters the line and the lower terminal exits the line. In case of special circumstances in the project that require the lower terminal to enter the line and the upper terminal to go out, due to the reason of arc extinguishing when breaking the fault current, the miniature circuit breaker must be used with reduced capacity, that is, the rated breaking capacity must be derated according to the relevant derating provided by the manufacturer. Capacity factor to convert.
Miniature circuit breaker construction and installation requirements:
1) The installation of the circuit breaker should meet the requirements of gb13955-92 size and product specification.
2) The installation of the circuit breaker should fully consider the power supply line, power supply method, power supply voltage, and system grounding type.
3) The rated voltage, rated current, short-circuit breaking capacity, and breaking time of the circuit breaker should meet the requirements of the protected power supply line and electrical equipment.
4) The installation and wiring of the circuit breaker should be correct. In the single-phase, three-phase three-wire, and three-phase four-wire power supply systems of different system grounding modes, the wiring of the residual current protector is consistent, and full attention should be given.

What is a Miniature Circuit Breaker?
It is mainly used for AC 50HZ or 60HZ, where the rated voltage is below 400V and the rated working current is below 63A. It is used for the overload and short circuit protection of lighting, distribution lines, and equipment of office buildings, residential buildings, and similar buildings. It can also be used for infrequent on-off operation and conversion of lines. It is mainly used in various places such as industry, commerce, high-rise buildings, and residential buildings.

What are the advantages of miniature circuit breakers?
1. The rated short-circuit breaking capacity is high, and some rated current levels can reach above 10KA.
2. Double wiring function, which can be easily connected to standard busbars and soft wires.
3. Combination terminals with finger touch protection for higher safety.
4. It is operated with an energy storage mechanism, and the contacts are closed quickly, which overcomes the adverse effects caused by the speed of manual operation of the handle and improves the service life of the product.
5. A variety of accessories are available, and the modularization and flexible combination make it very convenient for users to install.
6. The shell and some functional parts are made of high flame-retardant, high-temperature-resistant, and impact-resistant plastics imported from abroad.

Through the above simple induction, we roughly understand what the characteristics of thermal relays with reasonable prices are. The size of the miniature circuit breaker is small, because of its small size, it takes up less space in the room and has little effect on the appearance of the decoration. The other is that the flame retardant performance of miniature circuit breakers is high, and the safety performance of use is high for us.