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what is a circuit breaker?

2023-10-17

Do you know what a circuit breaker is? A circuit breaker is an instrument that can realize circuit switching. This kind of equipment is generally suitable for installation on switching devices and can realize power distribution. The function of the circuit breaker is relatively simple, mainly as a current protection device. Circuit breakers are installed in most circuits, which can effectively prevent various man-made disasters caused by circuit burnout or excessive voltage. What are the functions of the circuit breaker? What is the circuit breaker composed of? The following editor will introduce the working principle of the circuit breaker.

1. Circuit breaker

A circuit breaker (English name: circuit-breaker, circuit breaker) refers to a device that can close, carry and break current under normal circuit conditions and can close, carry and break current under abnormal circuit conditions within a specified time switchgear. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The division of high and low voltage boundaries is relatively vague. Generally, those above 3kV are called high-voltage electrical appliances. Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, and protect power lines and motors.

When they have severe overload or short circuit and undervoltage faults, they can automatically cut off the circuit. Its function is equivalent to the combination of fuse switch and overheating and underheating relay. Moreover, there is generally no need to change parts after breaking the fault current. At present, it has been widely used. Power distribution is an extremely important link in the generation, transmission and use of electricity. The power distribution system includes transformers and various high and low voltage electrical equipment, and the low voltage circuit breaker is an electrical appliance with a large amount of use.

2. Working principle of circuit breaker

A circuit breaker is generally composed of a contact system, an arc extinguishing system, an operating mechanism, a trip unit, and a housing. When short-circuited, the magnetic field generated by the large current (generally 10 to 12 times) overcomes the reaction force spring, the release pulls the operating mechanism to act, and the switch trips instantaneously. When overloaded, the current becomes larger, the heat generation is intensified, and the bimetal sheet is deformed to a certain extent to push the mechanism to move (the greater the current, the shorter the action time). There is an electronic type, which uses a transformer to collect the current of each phase, and compares it with the set value. When the current is abnormal, the microprocessor sends a signal to make the electronic release drive the operating mechanism to move. The function of the circuit breaker is to cut off and connect the load circuit, and cut off the faulty circuit, so as to prevent the expansion of the accident and ensure safe operation. The high-voltage circuit breaker needs to break 1500V, and the current is 1500-2000A arc, and these arcs can be stretched to 2m and still continue to burn without extinguishing. Therefore, arc extinguishing is a problem that must be solved for high voltage circuit breakers.

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