What is a circuit breaker?

‌A circuit breaker is a switching device that can close, carry and break the current under normal circuit conditions, and close, carry and break the current under abnormal circuit conditions within a specified time. Circuit breakers play an important role in protection and control in power systems. They are widely used in power distribution systems. They can distribute electrical energy, start asynchronous motors, and automatically cut off the circuit in the event of overload, short circuit or undervoltage, protecting power lines and electrical equipment. ‌

Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The boundary between high and low voltage is relatively vague. Generally, those above 3kV are called high-voltage electrical appliances.

Functions of circuit breakers

1. Control function: Circuit breakers can put electrical equipment or lines into or out of operation according to the needs of power grid operation. This is one of the most basic functions of circuit breakers.

2. Isolation function: When repairing electrical equipment or lines, circuit breakers can isolate the repaired parts from the live parts to ensure the safety of the repair personnel.

3. Protection function: When a power grid or electrical equipment fails, the circuit breaker can quickly cut off the faulty circuit to prevent the accident from expanding. This protection function is crucial to ensure the safe operation of the power grid.

4. Automatic reclosing function: For some transient faults, the circuit breaker can automatically reclose after cutting off the circuit to restore power supply. This helps to improve the power supply reliability and stability of the power grid.

Application of circuit breakers

1. Power generation

In the field of power generation, circuit breakers are mainly used for the protection and control of generator sets. When a generator set fails, such as short circuit, overload or ground fault, the circuit breaker can quickly cut off the fault circuit to prevent the fault from expanding and protect the generator set from damage. At the same time, the circuit breaker can also be used for the grid connection and disconnection operations of the generator set to ensure the stable operation of the generator set.

2. Power transmission field

In the field of power transmission, circuit breakers are mainly used for the protection and control of transmission lines. Transmission lines are an important part of the power system, and their safe and stable operation is crucial to the reliability of the entire power system. When a transmission line fails, the circuit breaker can quickly cut off the faulty line to prevent the fault current from impacting the power grid and protect the safe and stable operation of the power grid. In addition, circuit breakers can also be used for switching and parallel operation of transmission lines to improve the flexibility and reliability of the power grid.

3. Power distribution field

In the field of power distribution, circuit breakers are one of the most commonly used protective devices in the power distribution system. They are mainly used for overload, short circuit and ground fault protection of distribution lines, as well as protection of electrical equipment such as motors and transformers. When a distribution line or electrical equipment fails, the circuit breaker can quickly cut off the fault circuit to prevent the fault from expanding and protect the safety of equipment and personnel. At the same time, circuit breakers can also be used for automatic control and remote monitoring of the power distribution system to improve the operating efficiency and reliability of the power distribution system.