Product Introduction

KYN28A-12 indoor AC metal-armored mid-mounted switchgear. It is applicable to three-phase AC power system with rated voltage of 12kV and rated frequency of 50Hz. It is used to receive and distribute electric energy and control, protect and monitor the circuit. Conforming standards: GB3906-2006 3.6~40.5kV AC metal-enclosed switchgear and control equipment GB11022-89 General technical conditions for high-voltage switchgear IEC298 (1990) AC metal-enclosed switchgear and control equipment with rated voltage above 1kV and below 50kV and DL404-97 Ordering technical conditions for indoor AC high-voltage switchgear

Functions and features

The switchgear is designed according to the armored metal-enclosed switchgear in GB3906-91. The whole is composed of two parts: cabinet body and central withdrawable parts (i.e. handcart) (see figure). The cabinet is divided into four separate compartments, with the enclosure protection level of IP4X, and the level of IP2X when the door of each compartment and circuit breaker room is opened. It has overhead incoming and outgoing lines, cable incoming and outgoing lines and other functional schemes, and forms a complete set of power distribution system devices after arrangement and combination. The switchgear can be installed, debugged and maintained from the front, so it can be installed back to back, in a double arrangement and against the wall, improving the safety, flexibility and reducing the floor area of the switchgear.

◆ Shell and others

The main cabinet frame of the switchgear is made of aluminum-zinc coated steel sheet, processed by CNC machine tool, and adopts multiple folding process, which not only makes the whole cabinet have the advantages of high precision, strong corrosion resistance and oxidation resistance, but also makes the cabinet lighter in overall weight, higher in mechanical strength and beautiful in appearance than other similar equipment cabinets due to the multiple folding process. The cabinet body adopts an assembled structure, which is connected by rivet nuts and high-strength bolts, so that the processing cycle is short, the parts are universal, the floor area is small, and it is convenient to organize production.

◆ handcart

The handcart frame is made of thin steel plate processed by CNC machine tool and assembled. The handcart is insulated with the cabinet, and the mechanism interlocking is safe, reliable and flexible. According to the purpose, handcart can be divided into circuit breaker handcart, voltage transformer handcart, metering handcart, isolation handcart, etc. All kinds of handcart can be changed according to module and building block, and handcart of the same specification can be freely exchanged. The handcart has a disconnection position, a test position and a working position in the cabinet. Each position is equipped with a positioning device to ensure the reliability of the interlocking. It must be operated according to the interlocking anti-misoperation procedure. All handcart uses nuts and screw rods to move forward and exit. Its operation is light and flexible, and is suitable for the operation of the personnel on duty. When the handcart needs to be removed from the cabinet, a special transfer vehicle can be used for convenient withdrawal for various inspections and maintenance; Moreover, the central type is adopted, and the whole handcart is small in size, which is very convenient for inspection and maintenance.

◆ Compartment

The main electrical components of the switchgear have their own independent compartments, namely: circuit breaker handcart room, bus room, cable room, relay instrument room. The protection level between compartments shall reach IP2X; Except for the relay room, the other three compartments have their own pressure relief channels. Due to the adoption of the central type, the space of the cable room is greatly increased, so the equipment can be connected with multiple cables.

A. Tracks are installed on both sides of the isolation of the circuit breaker compartment for the handcart 15 to slide from the disconnected position and the test position to the working position in the cabinet. The diaphragm 13 (valve) of the static contact box 6 is installed behind the rear wall of the handcart room. When the handcart moves from the disconnected position, the test position to the working position, the valves on the upper and lower static contact boxes are linked with the handcart and automatically open at the same time; When moving in the opposite direction, the valve will automatically close until the handcart retreats to a certain position and covers the static contact box, forming effective isolation. Since the upper and lower valves can be operated separately, the valve on the live side can be locked during maintenance to ensure that the maintenance personnel do not touch the live body. When the door of the circuit breaker room is closed, the handcart can also be operated. Through the observation window of the middle door, the disposition and closing position of the handcart in the compartment can be observed and the energy storage status can be displayed.

B. The main bus 4 in the bus compartment is connected with each other through a single splice. It is fixed by branch bus 2 and fixed contact box. The main bus and tie bus are rectangular cross-section copper bars, which are assembled by two buses when used for heavy current load. The branch bus is connected to the static contact box 6 and the main bus through bolts, without other support. For special needs, the bus can be covered with heat-shrinkable sleeve and connecting bolt insulating sleeve and end cap, and the bus of adjacent cabinet can be fixed with sleeve 3. In this way, the air buffer reserved between the connecting buses can prevent it from melting in case of internal fault arc, and the bushing 3 can effectively limit the accident in this cabinet without spreading to other cabinets.

C. The switchgear in the cable compartment is of the central type, so the space in the cable compartment is large. Current transformer 7 and grounding switch 8 are installed on the rear wall of the compartment, and lightning arrester 10 is installed on the lower part of the rear of the compartment. After opening the door under the cabinet, the construction personnel can enter the cabinet from below for installation and maintenance. The cable connecting conductor in the cable room can connect 1 to 3 single-core cables per phase. If necessary, each phase can be connected with 6 single-core cables in parallel. The cabinet bottom of the connecting cable is equipped with a slotted removable non-metallic sealing plate or non-magnetic metal sealing plate, which ensures the convenience of construction.

D. Relay instrument room The relay instrument room can be equipped with relay protection elements, instruments, live monitoring indicators, and special secondary equipment. The control line is laid in the trunking with enough space and has a metal cover plate, which can isolate the secondary line from the high-voltage chamber. The left trunking is reserved for the introduction and exit of the small bus. The control line inside the switch cabinet is laid on the right side. A small bus crossing hole is also left on the top plate of the relay instrument room to facilitate construction. During wiring, the top cover plate of the instrument room can be turned over to facilitate the installation of small bus.

◆ The switch cabinet of interlock device to prevent misoperation has reliable interlock device, which meets the requirements of "five preventions".

A. Prompt buttons or KK-type change-over switches are installed on the door of the instrument room to prevent false closing and false opening of the circuit breaker

B. The circuit breaker can only be opened and closed when the circuit breaker handcart is in the test or working position, and after the circuit breaker is closed, the handcart cannot move, preventing the circuit breaker from being pushed and pulled by mistake with load.

C. Only when the grounding switch is in the opening position can the circuit breaker handcart move from the open and test position to the working position. The grounding switch can only be closed when the circuit breaker handcart is in the test and open position (the grounding switch can be equipped with a voltage display device), which can prevent the grounding switch from being closed by mistake when it is energized, and prevent the circuit breaker from being closed when the grounding switch is in the closed position.

D. When the grounding switch is in the opening position, both the lower door and the rear door cannot be opened to prevent entering the live space by mistake.

E. When the circuit breaker handcart is in the test or working position, but there is no control voltage, it can only be opened manually, not closed.

F. When the circuit breaker handcart is in the working position, the secondary plug is locked and cannot be pulled out.

G. Each cabinet can be equipped with electrical interlocking. The switchgear can also be equipped with an electromagnetic lock locking device on the operating mechanism of the grounding switch to improve reliability, and its order is selected according to the user's requirements.

◆ Pressure relief device

A pressure relief device is set above the circuit breaker handcart room, bus room and cable room. When the circuit breaker or bus has an internal fault arc, the air pressure inside the switch cabinet increases with the occurrence of the arc, and the front is sealed by a special sealing ring installed on the door. The pressure relief metal plate equipped on the top will be automatically opened to release pressure and discharge gas to ensure the safety of operators and switchgear.

◆ The secondary plug is interlocked with the position of the handcart

The connection between the secondary line of the switchgear and the secondary line of the circuit breaker handcart is realized through the manual secondary aviation plug. The movable contact of the secondary plug is connected with the circuit breaker handcart through a nylon corrugated telescopic tube, and the secondary static contact seat is installed at the upper right of the handcart room of the switch cabinet. Only when the circuit breaker handcart is in the test and disconnected position can the secondary plug be plugged in and released. When the circuit breaker handcart is in the working position, the secondary plug is locked and cannot be released due to the mechanical interlocking effect.

◆ Live display device

If the user has a demand, the switch cabinet can be equipped with an optional part to detect the operation of the primary circuit, that is, the live display device. The device is composed of high pressure sensor and display unit. This device can not only indicate the power-on status of the high-voltage circuit, but also cooperate with the electromagnetic lock to realize the forced locking of the grounding switch handle and the network door, so as to prevent the grounding switch from closing with power and entering the live space by mistake, thus improving the error-proof performance of the supporting products.

◆ Prevent condensation and corrosion

In order to prevent the danger caused by condensation in the climate environment with high humidity or large temperature change, heaters are installed in the circuit breaker room and cable room respectively, so as to use in the above environment and prevent corrosion.

◆ Grounding device

There are 5 separate sets in the cable room × The 40mm grounding copper bar runs through the adjacent switch cabinets and has good contact with the cabinet body. This grounding bar is used for components directly grounded. At the same time, the whole cabinet body is connected with aluminum-zinc coated plate, which makes the whole cabinet body in a good grounding state and ensures the safety of the operating personnel touching the cabinet body.

Working conditions

◇ Ambient air temperature: upper limit temperature+40 ℃. The lower limit temperature is - 15 ℃.

◇ Relative humidity: daily average relative humidity: ≤ 95%; The daily average water vapor pressure shall not exceed 2.2KPa;

Monthly average relative humidity: ≤ 90%; The monthly average water vapor force shall not exceed 1.8KPa.

◇ Altitude: below 1000m.

◇ Seismic intensity: no more than 8 degrees.

◇ The surrounding air shall not be obviously polluted by corrosive or combustible gas, water vapor, etc.

◇ There is no place with severe vibration.

◇ When it is used under normal conditions beyond the provisions of GB3906, the user and the company shall negotiate.

A handcart

The handcart frame is made of thin steel plate processed by CNC machine tool, riveted and welded. According to the purpose, handcart can be divided into circuit breaker handcart, voltage transformer handcart, isolation handcart, metering handcart, etc. handcart of the same specification can be easily interchanged. The handcart has isolation position, test position and working position in the cabinet, and each position is equipped with positioning device to ensure that the handcart cannot move freely when it is in the above position, and the interlock must be released when it is moved.

B Bus room

The bus is led from one switch cabinet to another and fixed by branch bus and static contact box. The flat branch bus is connected to the static contact box and the main bus through bolts, without any other clamp or insulator connection. When the user and the project have special needs, the connecting bolts on the bus bar can be sealed with insulation and end caps. When the bus passes through the partition of the switch cabinet, it shall be fixed with bus bushing. In case of internal fault arc, it can limit the spread of the accident to the adjacent cabinet and ensure the mechanical strength of the bus.

C Cable room

Current transformer, grounding switch, lightning arrester and cable can be installed in the cable room, and the slotted removable aluminum plate can be prepared at its bottom to ensure the convenience of on-site construction. D Relay meter room

The relay instrument room is used to install various relays, instruments, signal indicators, operating switches and other components. In addition, a small bus room can be added at the top of the instrument room according to the user's requirements, and 16 control small buses can be laid.

Pressure relief device

A pressure relief device is set above the handcart room, bus room and cable room. When an internal fault arc occurs in the circuit breaker or main bus and cable room, the air pressure inside the switch cabinet will rise with the occurrence of the arc. After reaching a certain pressure, the pressure relief metal plate of the top device will be automatically opened to release the pressure and discharge the gas, so as to ensure the safety of the operators and the switch cabinet.

Latch structure

The connection between the middle door and the cabinet body adopts a lock structure and is equipped with a lifting mechanism to make the middle door more convenient to open. When the middle door is closed, the connection strength between the middle door and the cabinet body is better, and the ability to effectively resist internal arcing fault is enhanced.