Detailed Explanation of High Voltage Switch Cabinet

basic definition

High-voltage switchgear refers to electrical products used in power generation, transmission, distribution, power conversion and consumption in power systems to perform switching, control or protection functions. The voltage level is between 3.6kV and 550kV. It mainly includes high-voltage circuit breakers and high-voltage isolation. There are several categories such as switches and grounding switches, high-voltage load switches, high-voltage automatic reclosing and sectionalizers, high-voltage operating mechanisms, high-voltage explosion-proof distribution devices and high-voltage switch cabinets. The high-voltage switch manufacturing industry is an important part of the power transmission and transformation equipment manufacturing industry and occupies a very important position in the entire power industry. Some people are willing to call the high-voltage switch cabinet high-voltage distribution cabinet, but it is actually the same thing...

Function: The high-voltage switch cabinet has functions such as overhead incoming and outgoing lines, cable incoming and outgoing lines, and busbar contact.

Application: Mainly suitable for various places such as power plants, substations, power system substations, petrochemical industry, metallurgical steel rolling, light industry and textile, factories and mines, residential areas, high-rise buildings, etc.

Composition: The switch cabinet should meet the relevant requirements of the "AC Metal Enclosed Switchgear" standard and consists of two parts: the cabinet and the circuit breaker. The cabinet consists of the shell, electrical components (including insulating parts), various mechanisms, secondary terminals and Composed of wiring etc.

Five defenses:

1. Prevent closing with load: After the vacuum circuit breaker trolley in the high-voltage switch cabinet is closed in the test position, the trolley circuit breaker cannot enter the working position.

2. Prevent closing with ground wire: When the ground knife in the high-voltage switch cabinet is closed, the trolley circuit breaker cannot be closed.

3. Prevent accidental entry into the live compartment: When the vacuum circuit breaker in the high-voltage switch cabinet is closing, the back door of the cabinet is locked with the machine on the grounding knife and the cabinet door.

4. Prevent the grounding wire from being closed when it is charged: If the vacuum circuit breaker in the high-voltage switch cabinet is closed during operation, the closed grounding knife cannot be put in.

5. Prevent the under-loaded broach switch: When the vacuum circuit breaker in the high-voltage switch cabinet is closed and running, it cannot exit the working position of the trolley circuit breaker.

Structure and composition

It is mainly composed of cabinet, high-voltage vacuum circuit breaker, energy storage mechanism, trolley, grounding knife switch and comprehensive protector.

①Cabinet

It is pressed and formed with iron plates and has a closed structure. It is equipped with an instrument room, a trolley room, a cable room, a busbar room, etc. Each room is isolated by iron plates, as shown in Figure 1. The instrument room is equipped with comprehensive protectors, ammeters, voltmeters and other devices; the trolley room is equipped with trolleys and high-voltage vacuum circuit breakers; the busbar room is equipped with three-phase busbars; and the cable room is used to connect power cables to the outside.

②High voltage vacuum circuit breaker

The so-called high-voltage vacuum circuit breaker installs its main contacts in a closed vacuum chamber. When the contacts are turned on and off, the arc has no gas to support combustion, so it will not burn out and is durable. At the same time, the insulating material is used as the base to improve the vacuum switch. Excellent insulation performance, so it is called high-voltage vacuum circuit breaker.

③Car mechanism

Install the high-voltage vacuum circuit breaker on the trolley and move with the trolley. When you shake the handle clockwise, the trolley enters the cabinet and carries the vacuum circuit breaker into the high-voltage circuit. When you shake the handle counterclockwise, the trolley exits the cabinet and drives the vacuum circuit breaker. Pull out the high-voltage circuit, as shown in Figure 2.

④Energy storage mechanism

A small motor drives the spring to store energy, and the spring releases kinetic energy to close the vacuum circuit breaker.

⑤Grounding knife switch

It is a knife switch that acts as a safety interlock. The high-voltage cabinet door can only be opened when the grounding knife switch is closed. Otherwise, when the grounding knife switch is not closed, the high-voltage cabinet door cannot be opened, which plays the role of safety interlock protection.

⑥Integrated protector

It is a kind of microcomputer protector, which is composed of microprocessor, display screen, buttons and peripheral circuits. Used to replace the original overcurrent, overvoltage, time and other relay protection circuits. Input signals: signals from current transformers, voltage transformers, zero-sequence current transformers and switching values; the keyboard can be used to set current values, voltage values, quick-break time, start-up time and other data; the display screen can display real-time data and input control, execution Protective action.

Form classification

(1) According to the main wiring form of the switch cabinet, it can be divided into bridge wiring switch cabinet, single busbar switch cabinet, double busbar switch cabinet, single busbar segmented switchgear, double busbar switch cabinet with bypass busbar and single busbar segmented switchgear. Switchgear with bypass busbar.

(2) According to the installation method of the circuit breaker, it can be divided into fixed switch cabinet and removable (handcart type) switch cabinet.

(3) According to the cabinet structure, it can be divided into metal-enclosed partitioned switch cabinets, metal-enclosed armored switch cabinets and metal-enclosed box-type fixed switch cabinets.

(4) According to the installation position of the circuit breaker handcart, it can be divided into floor-standing switch cabinet and center-mounted switch cabinet.

(5) According to the different insulation media inside the switch cabinet, it can be divided into air insulated switch cabinet and SF6 gas insulated switch cabinet.

The main technical parameters

1. Rated voltage, rated current, rated frequency, rated power frequency withstand voltage, rated lightning impulse withstand voltage;

2. The circuit breaker has moderate rated breaking current, rated closing peak current, rated short-time withstand current, and rated peak withstand current;

3. The grounding switch has rated closing peak current, rated short-time withstand current and rated peak withstand current;

4. The rated voltage, DC resistance, and power of the opening and closing coil of the operating mechanism, and the rated voltage and power of the energy storage motor;

5. The protection level of the cabinet and the national standard number it conforms to.

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