A circuit breaker refers to a switching device that can close, carry, and disconnect current under normal circuit conditions, and can close, carry, and disconnect 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 usage scope. The boundary between high and low voltage is relatively vague, and those above 3kV are generally referred to as high voltage electrical appliances.

Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, protect power lines and motors, and automatically cut off circuits when they experience serious overload, short circuit, undervoltage, and other faults.

Their function is equivalent to a combination of fuse type switches and over/under heat relays. And generally, there is no need to change the components after disconnecting the fault current. It has been widely applied.

Surrounding air temperature: upper limit of surrounding air temperature+40 ℃; ○ Lower limit of ambient air temperature -5 ℃; The average temperature of the surrounding air for 24 hours shall not exceed+35 ℃.

Altitude: The altitude of the installation site shall not exceed 2000m.

Pollution level: The pollution level is level 3.

Control circuit:

1. It should be able to monitor the integrity of the control circuit protection device and its tripping and closing circuits to ensure the normal operation of the circuit breaker;

2. It should be able to indicate the normal closing and opening position status of the circuit breaker, and have clear indication signals during automatic closing and automatic tripping;

3. After the completion of closing and tripping, the command pulse should be able to be released, that is, the power supply for closing or tripping should be cut off;

4. When there is no mechanical anti jump device, an electrical anti jump device should be installed;

5. The accident tripping signal circuit of the circuit breaker should be wired according to the "non corresponding principle";

6. For equipment that may experience abnormal working conditions or malfunctions, warning signals should be installed;

7. The power supply for spring operated mechanisms and manual operated mechanisms can be DC or AC, while the power supply for electromagnetic operated mechanisms requires DC.