A brief introduction to the composition of the switchgear of the power system
The control cabinet is divided into partitions:
1. Bus room: main busbar, branch busbar.
The bus room is arranged in the upper part of the back of the switch cabinet, which is used for installing and arranging the three-phase high-voltage AC bus and connecting with the static contact through the branch bus. All bus bars are molded with insulating sleeves. When the bus passes through the switch cabinet partition, it is fixed with a bus sleeve. In the event of an internal fault arc, it can limit the spread of the accident to the adjacent cabinet and ensure the mechanical strength of the busbar.
2. Handcar room: circuit breaker handcart, handcart operating mechanism.
The handcart room (also known as the circuit breaker room) is equipped with specific rails inside for the circuit breaker handcart to slide and work. The trolley can be moved between the working position and the test position. The partition (valve) of the static contact is mounted on the rear wall of the handcart chamber. When the handcart moves from the test position to the working position, the partition automatically opens, and the handcart moves in the opposite direction to fully composite, thus ensuring that the operator does not touch the charged body.
3. Cable room: voltage transformer, current transformer, lightning arrester, zero sequence current transformer, high-voltage cable, voltage sensor. Grounding trolleys, heating devices, etc.
Ancillary equipment such as current transformers, grounding switches, lightning arresters (overvoltage protectors) and cables can be installed in the cable room, and a removable aluminum plate with a seam at the bottom of it can be prepared to ensure the convenience of on-site construction.
The current transformer --- measure the outgoing current value and provide current signals for ammeters, metering devices, protection devices, etc.
Voltage transformers are --- used to supply power to measuring instruments and relay protection devices, and are used to measure the voltage, power and electrical energy of the line.
The lightning arrester --- an overvoltage protection device for the equipment, which is connected in parallel on the outlet side of the circuit breaker, and generally does not need to be operated after the normal operation of the equipment.
Voltage Sensors--- Sensors of Live Display Devices provide live signals for live display devices and electric locks.
The three-phase current of the zero-sequence current transformer --- the outgoing high-voltage cable passes through the center of the zero-sequence current transformer under normal conditions, and the three-phase current is zero, when the single-phase grounding occurs, the secondary coil will have an induced current, and the relay will be driven to make the protection device move.
Grounding switch --- in the medium voltage system, such as the line outlet switch or power inlet switch in the 10kV system, etc., for the sake of safety, when the circuit breaker is disconnected, the line three-phase short circuit and grounding, and this line three-phase short circuit and grounding function, is to use a group of knife switches to achieve, that is, when the circuit breaker has been disconnected, at the same time the line three-phase short circuit and grounding. This knife room is the grounding knife switch.
4. Low-voltage chamber: protection device, operation button, indication device, secondary control cable, etc.
On the panel of the low-pressure chamber, a microcomputer protection device, an operation button, a protective outlet pressure plate, an instrument, a status indicator (or a status display) and so on are installedIn the relay room, there are terminal strips, DC power switches for microcomputer protection control loops, DC power supplies for microcomputer protection, power switches (DC or AC) for energy storage motors, and secondary equipment with special requirements.