Basic knowledge of switchgear

one. Basic knowledge

Switchgear is a common name for metal-enclosed switchgear. In the bus section system, it is used to receive and distribute electric energy, and to control, protect, monitor and measure the power circuit. By definition, a metal-enclosed switchgear is a switchgear that is completely enclosed by a metal casing, except for incoming and outgoing wires.

It is an electrical equipment based on circuit breakers: it means that the manufacturer, according to the requirements of the main electrical wiring diagram, connects the relevant high and low voltage electrical appliances (including control electrical appliances, protective electrical appliances, and measuring electrical appliances) as well as busbars, current-carrying conductors, insulators, etc. Assembled in a closed or open metal cabinet as a device for receiving and distributing electrical energy in the power system.

In the operating conditions of the switchgear, the upper limit temperature is 40 degrees, the lower limit is -5 degrees in general areas, and -15 degrees in severe cold areas.

Second, the classification of switchgear

1. Inlet cabinet

Also called power receiving cabinet, it is a device used to receive electric energy from the grid (from the incoming line to the busbar), and is generally equipped with components such as circuit breakers, CTs, PTs, and isolation knives.

2. Outlet cabinet

Also called feeder cabinet or power distribution cabinet, it is a device used to distribute electric energy (from the busbar to each outgoing line), and is generally equipped with circuit breakers, CTs, PTs, isolation knives, etc.

3. Bus connection cabinet

Also called busbar breaker, it is a device used to connect two sections of busbars (from busbar to busbar). It is commonly used in single-busbar segment and double-busbar systems to meet the requirements of different operating modes and to ensure selective grounding in case of failure. Shedding load.

4. PT cabinet

Also called voltage transformer cabinet, it is generally installed directly on the busbar to detect the busbar voltage and realize the protection function. Inside is equipped with PT, isolation knife, fuse, lightning arrester, etc.

5. Isolation cabinet

It is used to isolate two sections of busbars or to isolate power receiving equipment and power supply equipment. It can provide operators with a visible terminal to facilitate maintenance and repair operations. Since the isolation cabinet does not have the ability to break and connect the load current, the handcart of the isolation cabinet cannot be pushed or pulled when the circuit breaker matched with it is closed. Under normal circumstances, the interlock between the auxiliary contact of the circuit breaker and the isolated handcart will be set to prevent misoperation.

6. Measuring cabinet

It is also divided into high-voltage and low-voltage metering, and is generally installed with isolating switches, fuses, CT, PT, active energy meters, reactive energy meters, relays, and first-line auxiliary secondary equipment such as load monitors.

7. SVG

Static var generator, also known as high-voltage dynamic var compensation generating device, or static synchronous compensator. It is the best solution in the field of reactive power control.

8. The gas-filled switchgear combines circuit breakers, isolating switches, grounding switches, CT, PT, busbars, etc. in a metal shell, and then uses gas with good insulation and arc extinguishing performance as phase-to-phase and ground-to-ground insulation measures.

9. The 10 kV switchgear is divided into central cabinet and ring network cabinet. The full name of the central cabinet is the metal armored central removable switchgear, which belongs to the high-voltage power distribution device. The maximum working voltage is 3.6, 7.2, and 12 kV. Inner complete set of power distribution device.

Ring network cabinet. It is a high-voltage switchgear installed in a metal or non-metal insulated cabinet or made into an assembled interval ring network power supply unit. The core part uses a load switch and a fuse. It has a simple structure, small size, low price, and Improve power supply parameters and performance and power supply security and other advantages.

10. Box change. The box-type substation is a kind of high-voltage switchgear, which is suitable for mines, factories, enterprises, oil and gas fields and wind power stations, replacing the original civil power distribution room.