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breaker

Posted on: 11/18/2021

1. What is a circuit breaker

Circuit breaker refers to a switching 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. 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 is relatively fuzzy. Generally, those above 3kV are called high-voltage electrical appliances.

2. Circuit breaker wiring diagram

1. 1P air switch is also called single-pole air switch. It has only one inlet and one outlet, so it only needs to be connected to the live wire.

2. Two-phase air switch is also called 2P air switch. If the air switch is not marked with L and N, it is better to wire it according to the habit of left zero and right fire.

3. The leakage protector is also called the leakage air switch. The wiring schematic diagram of the household air switch is as follows:

3. The working principle of the circuit breaker

The inside of the circuit breaker is generally composed of a contact system, an arc extinguishing system, an operating mechanism, a trip unit, and a casing. Its function is to cut off and connect the load circuit, and cut off the fault circuit, to prevent the expansion of accidents and ensure safe operation. Therefore, the working principle of the circuit breaker is as follows:

1. When a short circuit occurs, 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 move, and the switch instantaneously trips.

2. When the overload occurs, the current becomes larger, the heat generation increases, and the bimetallic strip deforms to a certain extent to push the mechanism to move, thereby causing the switch to trip; the larger the current, the shorter the action time.

3. There is an electronic type, the current of each phase is collected by a transformer, and compared with the set value, when the current is abnormal, the microprocessor will send a signal to make the electronic tripper drive the operating mechanism.

4. The role of circuit breakers

Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, and protect power lines and motors. They can automatically cut off the circuit when they experience serious overload, short circuit, and undervoltage faults. Its function is equivalent to a fuse switch Combination with overheating and underheating relays, etc. Moreover, it is generally not necessary to change parts after breaking the fault current.
At present, it has been widely used. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The distinction between high and low voltage is relatively vague. Generally, those above 3kV are called high-voltage electrical appliances.