Disconnect switches and circuit breakers are two common devices used in electrical systems to control and protect electrical equipment and personal safety. They have different functions and working principles, but both play a vital role in the circuit.

I. Isolator Switch

Isolator Switch (Isolator Switch), also known as knife switch or knife cutter switch, is used to cut off the connection between the electrical equipment and the power supply, in order to realize the safety maintenance of the electrical equipment and the isolation of part of the circuit.

Symbol

The symbol of the Isolator Switch is a triangle showing the open state with a vertical straight line in the center, indicating the disconnection between the electrical equipment and the power supply.

Principle of operation

The main function of the disconnecting switch is to cut off the connection between the equipment and the power supply so that the equipment can be serviced, maintained or replaced. Under normal circumstances, the disconnecting switch is in a closed state, the equipment is connected to the power supply and the current can flow normally. When it is necessary to isolate the equipment, the operator can pull the handle of the disconnecting switch or turn the switch handle to make the disconnecting switch in the disconnected state and cut off the connection between the equipment and the power supply.

It should be noted that the disconnecting switch does not disconnect the circuit with current, it is only used to cut off the connection between the electrical equipment and the power supply, and does not have overload and short-circuit protection functions. Therefore, when operating the disconnecting switch, you must make sure that the circuit has been disconnected and no current is flowing through it to avoid electric shock and other dangers.

II. Circuit Breaker

A circuit breaker (Circuit Breaker) is a switching device that can automatically break a circuit and is used to protect electrical equipment and circuits from damage caused by overloads and short circuits.

Symbol

The symbol of a circuit breaker is a point with a horizontal line in the center, with vertical lines attached to each side, indicating the state of breaking the circuit.

Principle of operation

The main function of a circuit breaker is to protect electrical equipment and circuits from damage by automatically disconnecting the circuit when the circuit is overloaded or short-circuited. When the current exceeds the set value, the circuit breaker will quickly disconnect the circuit and stop the current flow. When the fault is removed or the load returns to normal, the circuit breaker can be manually or automatically reclosed to restore normal power to the circuit.

Circuit breakers have a variety of protection functions, including overload protection, short-circuit protection, under-voltage protection, phase loss protection, etc., which can effectively prevent damage to electrical equipment and circuits, and ensure the safety of personnel. Compared with the disconnecting switch, the circuit breaker can actively detect current abnormalities and automatically cut off the circuit without manual intervention, which is safer and more reliable.

Summary:

Disconnect switches and circuit breakers both play an important role in the electrical system, but the working principle and function are different. Disconnect switches are used to cut off the connection between the equipment and the power supply, to realize the safe maintenance of the equipment and the isolation of part of the circuit; while circuit breakers are used to automatically disconnect the circuit, to protect the electrical equipment and circuits from the damage of overloads and short circuits.

In the safe operation in the electrical system, people should operate the disconnect switches and circuit breakers in strict accordance with the symbols in the circuit diagrams to ensure the safety of the equipment and personnel. In addition, regular inspection and maintenance of electrical equipment and timely replacement of aged and damaged switches and circuit breakers are also important measures to ensure the safety of electrical systems.