For the control of circuit breakers in high-voltage switchgear, the installation of high-voltage switchgear is to control its closing and opening. According to the control location, the production and wholesale of high-voltage switchgear are divided into on-site control and centralized control. Manually operate the manual operating mechanism near the circuit breaker or use button control (through electromagnets or motors) to complete the closing and closing tasks, i.e. on-site operation. This method can save investment, cables, and secondary equipment. Centralized control is carried out in the main control room, such as generators, main transformers, bus sections, bus contactors, and other equipment, all of which adopt centralized control methods. In this control mode, there is usually a distance of tens to hundreds of meters between the controlled circuit breaker and the main control room, hence it is also known as "remote control".
Control the circuit breaker through auxiliary circuits. The control switch or button should be installed on the control screen in the main control room, which can issue closing and closing commands. The operating mechanism (i.e. closing and closing coils) should execute commands on the circuit breaker. The control console is connected to the operating mechanism through a control wire.
The electrical circuit used to close and open the circuit breaker is called a control circuit. According to the type of operating power supply, the control circuit can be divided into DC operation and AC operation; According to the wiring and equipment, there are strong current control and weak current control.
Basic requirements for circuit breaker control circuits:
There are a variety of switch models and operating mechanisms, resulting in a wide variety of control circuits. However, their basic requirements are the same.
(1) It can be closed and opened, and can also be automatically closed and opened through relay protection and automatic devices. After the closing and opening work is completed, it should be able to automatically cut off the closing and opening circuit to avoid burning the coil.
(2) It can indicate the closing and opening positions of the circuit breaker. When the circuit breaker is in the closed position, the traffic lights will light up; At the opening position, the green light is on. Flashing indicates its automatic closing and opening status. The controller has a fuse protection device.
(3) Capable of monitoring the integrity of control circuits and power supplies.
(4) Equipped with mechanical or electrical anti jump locking devices.
(5) The wiring should be simple and reliable.
