Five minutes to understand the switchgear

The structure of high-voltage switchgear is generally similar, mainly divided into busbar room, circuit breaker room, secondary control room (instrument room), and feeder room, with steel plate isolation between each room. Low voltage switchgear is mainly classified based on the installation method of components

KYN28A-12 Armored Mid mounted High Voltage Switchgear

KYN61-40.5 Armored Removable Metal Enclosed Switch Cabinet

GGD low-voltage fixed switchgear

MNS low-voltage withdrawable switchgear

GCK low-voltage withdrawable switchgear

Internal components include: busbar (busbar), circuit breaker, conventional relay, comprehensive relay protection device, measuring instrument, isolation switch, indicator light, grounding switch, etc.

1. Incoming cabinet

Also known as a receiving cabinet, it is a device used to receive electrical energy from the power grid (from the incoming line to the busbar), usually equipped with circuit breakers, CT, PT, isolation knives, and other components.

2. Outgoing cabinet

Also known as a feeder cabinet or distribution cabinet, it is a device used to distribute electrical energy (from the busbar to various outgoing lines), usually equipped with circuit breakers, CT, PT, isolation knives, and other components.

3. Bus connection

Also known as busbar breaking cabinet, it is a device used to connect two sections of busbar (from busbar to busbar). In single busbar segmented and double busbar systems, busbar connection is often used to meet the requirements of users for selecting different operating modes or to ensure selective load cutting in case of faults.

4. PT cabinet

The voltage transformer cabinet is usually directly installed on the busbar to detect busbar voltage and achieve protection functions. Internally, voltage transformers PT, isolation knives, fuses, and lightning arresters are mainly installed.

5. Isolation cabinet

It is used to isolate the busbars at both ends or to isolate the receiving equipment from the power supply equipment. It can provide a visible endpoint for operators to facilitate maintenance and repair operations. Due to the fact that the isolation cabinet does not have the ability to break or connect load current, it is not possible to push or pull the handcart of the isolation cabinet when the circuit breaker that matches it is closed. In general applications, it is necessary to set up an interlock between the auxiliary contact of the circuit breaker and the isolation handcart to prevent misoperation by operators.

6. Capacitor cabinet

Also known as compensation cabinet, it is used to improve the power factor of the power grid, or to compensate for reactive power. The main components are protective appliances such as capacitor banks, switching control circuits, and fuses that are connected in parallel. Generally installed in parallel with the incoming cabinet, one or more capacitor cabinets can operate in parallel. After the capacitor cabinet is disconnected from the power grid, as the capacitor bank requires a period of time to complete the discharge process, it is not possible to directly touch the components inside the cabinet, especially the capacitor bank; Within a certain period of time after a power outage (depending on the capacity of the capacitor bank, such as 1 minute), it is not allowed to reclose to avoid overvoltage damage to the capacitor. When performing automatic control functions, it is also important to allocate the switching frequency of each group of capacitor banks reasonably to avoid situations where one group of capacitors is damaged while the other groups are rarely switched.

7. Measuring cabinet

It is mainly used for measuring electrical energy (kilowatt hours), and can be divided into high voltage and low voltage. It is generally installed with isolation switches, fuses, CT, PT, active energy meters (traditional instruments or digital meters), reactive energy meters, relays, and some other auxiliary secondary equipment (such as load monitors, etc.).

8. GIS cabinet

Also known as a closed combination electrical cabinet, it is a metal enclosure that combines circuit breakers, isolation switches, grounding switches, CT, PT, lightning arresters, busbars, etc., and then uses gas with good insulation and arc extinguishing performance (usually sulfur hexafluoride SF6) as insulation measures between phases and to ground. It is suitable for high voltage and high capacity power grids,

9. Circuit breaker

Under normal working conditions, the circuit breaker is in a closed state (except for special applications) and the circuit is connected. When conducting automatic control or protective control operations, the circuit breaker can be operated to open or close the circuit under the control of the comprehensive protection device. Circuit breakers can not only break normal load currents, but also withstand short circuit currents for a certain period of time (several times or even dozens of times the normal working current), and can break short circuit currents, cut off faulty lines and equipment. So, the main function of a circuit breaker is to break and connect the circuit (including breaking and connecting normal current, breaking short circuit current).

Due to the inevitable occurrence of electric arcs between the moving and stationary contacts of the circuit breaker during the process of breaking and connecting the circuit. In order to protect the contacts, reduce the loss of contact materials, and reliably break the circuit, measures must be taken to extinguish the arc as soon as possible. One way is to use different arc extinguishing media to fill between the dynamic and static contacts of the circuit breaker.

According to different arc extinguishing media, circuit breakers can be divided into: oil circuit breakers (with more or less oil), sulfur hexafluoride (SF6) circuit breakers, vacuum circuit breakers, air circuit breakers, etc. The main primary equipment in the high and low voltage switchgear that we often come into contact with in engineering is the circuit breaker. Due to the fact that the dynamic and static contacts of a circuit breaker are generally enclosed in a container filled with arc extinguishing medium, the opening and closing status of the circuit breaker cannot be directly determined. It is generally determined by the auxiliary devices of the circuit breaker (such as the opening and closing position pointer).

10. Isolation knife

The isolation switch (also known as an isolation switch) is mainly used to isolate high-voltage power sources and ensure safe maintenance of lines and equipment due to its obvious fracture that can be identified for connection or disconnection. The current that can be disconnected is very small (usually only a few amperes). Due to the lack of a dedicated arc extinguishing device, it cannot be used to break fault current and normal working current, and it is not allowed to perform breaking operations with load.

11. Fuses

A fuse is a simple circuit protection device, whose principle is that when the current flowing through the fuse reaches or exceeds a fixed value for a certain period of time, its own melt melts and cuts off the circuit. Its action principle is simple, easy to install, and generally not used alone. It is mainly used in conjunction with other electrical appliances. Main operating characteristics: Firstly, the current must reach a certain value, which is already set before the fuse is shipped and cannot be changed; The second is that after the current reaches a certain value, it takes a certain time, which is also prepared by the manufacturer and cannot be changed. However, there are many types of actions, including delayed action, fast action, ultra fast action, etc; Thirdly, the body is damaged after operation and cannot be reused and must be replaced; Whether a fuse is blown can be determined by a fuse indicator or by the appearance of the melt; Commonly used fuses and fuses belong to the scope of this type of electrical appliance.

12. Load switch

The load switch has a simple arc extinguishing device, and the arc extinguishing medium is generally air. It can connect and disconnect a certain amount of current and overcurrent, but cannot break short circuit current and cannot be used to cut short circuit faults. So it is absolutely not allowed to replace circuit breakers solely with load switches; If a load switch is to be used, it must be used in conjunction with the high-voltage fuse mentioned earlier (in fact, fuses and load switches are often used in series as simple overload protection to reduce engineering costs). Load switches, similar to disconnectors, have clear opening gaps, making it easy to determine whether the circuit is in a connected or disconnected state

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Datasheet
1.1 710-512-01-MVS1 Main Substation
Incoming Switchgear A01 B01 2
No Components Specification Unit Qty Maker
1 VCB
HVX12-50-31-F 275mm
Altitude ≤2000m
Opening voltage DC220V
Closing voltage DC220V
Energy storage voltage DC220V
Set 1 China
2 VT JDZ-10 10KV/√3/0.1KV/√3 Set 3 China
3 CT
LZZBJ9-12 3000/1A 5P20 10VA
5P20 5VA 5Fs5 5VA
Set 3 China
4 High voltage fuse XRNP1-12 0.5A Pc 3 China
5 Lightning arrester HY5WZ-17/50 Set 3 China
6 Intelligent control panel WY-9008A Pc 1 China
7 Short circuit and ground fault indicator EKL-4-1 Pc 1 China
8 Multifunctional electric instrument PD666-3S3 380V 5A Pc 1 China
9 Primary harmonic eliminator LXQ-12KV Pc 1 Fengyuan
10 Charged display DXN-12Q Pc 1 China
11 Temperature and humidity controller WY-CS-III Pc 1 China
12 Connecting piece JY-2 Pc 3 China
13 Junction box PJ1 Pc 1 China
14 Metering bracket Universal type Pc 1 China
15 Signal lamp ND16-22D/4 AC380V red Pc 1 CHNT
16 Signal lamp ND16-22D/4 AC380V green Pc 1 CHNT
17 Signal lamp ND16-

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