Analysis of working principle of high and low voltage switchgear

Working principle of high voltage switchgear

High voltage switchgear mainly includes circuit breaker, isolation switch, load switch and so on. They are used to handle current in high-voltage circuits and typically operate in voltage classes of 3.6kV and above.

Circuit breaker: As a nuclear and core high-voltage switchgear, it can open and close the circuit under normal working conditions, but also automatically disconnect the circuit in an abnormal state (such as overload or short circuit) and interrupt the fault current. The core and core working principle of the circuit breaker depends on its internal protection mechanism, including overcurrent release and short circuit release, when the current is detected to exceed the specified threshold, these devices will trigger the mechanical or electronic system to quickly disconnect the circuit to prevent the occurrence of system damage or fire and other safety accidents.

Isolation switch: Its main function is to provide a visible and reliable insulation distance after the circuit is disconnected to ensure the safe maintenance of the equipment or line. Isolation switch can not be operated under the load, its working principle is based on physical partition, through a direct physical space interval to block the current, to achieve the purpose of safety maintenance.

Load switch: Compared with the isolation switch, the load switch can be opened and closed under load conditions. It is mainly used to switch the load, not to cut off the fault current. The load switch is usually equipped with an arc extinguishing device, and the arc extinguishing technology is used to deal with the arc problem during breaking.

Working principle of low voltage switchgear

Low-voltage switchgear usually operates between 50V and 1000V AC or DC and includes contactors, relays, low-voltage circuit breakers, etc.

Contactor: Used to turn on and off the current frequently at a distance, but not used to cut off the fault current. The contactor draws and releases the contact through an electromagnet to connect and disconnect the circuit.

Relay: An automatic switch that usually operates based on electromagnetic, thermal, or other physical effects. Its working principle is to feel a certain input (such as voltage, current, temperature, pressure, etc.) changes, to achieve the transition of small current control large current, low voltage control high voltage.

Low-voltage circuit breaker: also known as low-voltage circuit breaker, with automatic disconnect and manual disconnect function. In case of overload or short circuit, the built-in trip mechanism can automatically disconnect the circuit and protect the line and equipment.

conclusion

High and low voltage switchgear plays a vital role in power system. The high-voltage switch focuses on handling the current in the high-voltage environment, while the low-voltage switch focuses more on the control and protection of the low-voltage circuit. Each type of switchgear has its own unique working principles and application scenarios, but their common goal is to ensure the safe and stable operation of the power system. With the development of science and technology, high and low voltage switchgear is becoming more intelligent and miniaturized, providing a more reliable and efficient means of protection and control for modern power grids.