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Ring network cabinet structure and principle_Introduction to the types and characteristics of ring network cabinets
Release time:
2019-08-14
Ring network refers to a ring-shaped distribution network, that is, the power supply trunk forms a closed ring, and the power supply supplies power to this ring trunk line, and then distributes power to the outside through the high-voltage switch all the way from the trunk line. The advantage of this is that each distribution branch can take power from its left mains and its right mains. When the left main line fails, it continues to receive power from the right main line, and when the right main line fails, it continues to receive power from the left main line, so that although the main power supply is single-circuited, However, from each distribution branch, the benefits similar to dual-circuit power supply are obtained, thereby improving the reliability of power supply.
The so-called "ring main unit" means that each distribution branch is equipped with a switch cabinet (outgoing switch cabinet), and the busbar of this switch cabinet is also a part of the ring trunk. That is to say, the ring trunk is formed by connecting the busbars of each outlet cabinet. Each outlet cabinet is called "Ring Main Unit".
The role of the ring network cabinet
The function of the ring network cabinet is to connect the ring network line and improve the power supply reliability of the line, such as the ring network line closing operation or the ring network line load cutover. Ring network cabinets are used in different parts of the ring network and are slightly different in classification, mainly including incoming ring network cabinets, emergence ring network cabinets and contact ring network cabinets.
The principle of ring network cabinet
It is to realize the mutual supply of lines, that is, after different lines come out from different substations, they will hold hands with each other. Under normal circumstances, the connection will be disconnected, and they will operate separately. , close the connection, and let another substation carry the load originally brought by the original substation. Or a line or substation with a high load, and another with a low load, can selectively disconnect from a contact point, and share a part of the load by the line or substation with a lower load, which not only ensures The reliability of the power supply and the stable operation of the power grid are also ensured.
Structural characteristics of ring main unit
a. The ring network cabinet is composed of four parts: switch room, fuse room, operating mechanism room and cable room (chassis).
b. The switch room is composed of various functional circuits (including earthing switches and load switches) sealed in the metal shell and the bus bars between the circuits. The shell is welded by 3mm cold-rolled steel plate (or non-embroidered steel plate). Each functional circuit includes a load switch and grounding switch. The load switch is composed of a vertically moving moving contact system and a static contact located at the lower end. When the switch is closed, the moving contact moves downward and the load switch is turned on. The grounding switch is composed of a moving contact blade and a static contact blade. During the movement of the spring, the grounding switch is quickly turned on. There are 4 rectangular assembly process holes in the upper and rear of the switch room, and the front of the ring network cabinet is equipped with an observation window, which can see the "off" and "on" positions of the grounding switch. An explosion-proof device is installed at the rear of the ring main unit.
c. The load switch adopts a compressed air blowing structure, which has strong arc extinguishing ability and does not affect the insulation between phases and ground. Both the dynamic and static contacts have arc contacts, which greatly improves the breaking times.
d. The fuse and the load switch room form a transformer protection circuit. The high-voltage current-limiting fuse is installed in the epoxy cast insulating shell. After the fuse is blown, the striker is ejected and the load switch is opened.
e. The operating mechanism room is located on the front of the ring main unit. In each functional circuit, the load switch is equipped with a human (or electric) energy storage spring operating mechanism, and the grounding switch is equipped with a human energy storage spring operating mechanism. They are respectively used for load switch closing operation and manual opening rotary knob and opening and closing operation holes of grounding switch, load switch opening and closing position indicator lights and electric opening and closing buttons, and are equipped with analog lines, switch status Display card and lock position, the operation of load switch and grounding switch has interlocking device to prevent misoperation.
Types of Ring Main Units:
1. Vacuum ring network cabinet: The vacuum ring network cabinet is a new generation of environmentally friendly solid insulation vacuum ring network cabinet products. This product adopts vacuum circuit breaker + microcomputer protection device, and all conductive circuits are wrapped with epoxy resin or silicone rubber. It ensures high safety of operation and operation, and the use voltage level can reach up to 24KV.
2. SF6 ring network cabinet: SF6 ring network cabinet is a combination of air-insulated or gas-insulated medium-voltage electrical appliances with load switch as the core component that can be freely combined into multi-circuit entry and exit with switching, contacting and protecting power system functions. Its main circuit core components are composed of SF6 load switch or additional circuit breakers and other primary auxiliary appliances.
3. Gas-producing ring network cabinet: Gas-producing ring network cabinet is made of solid gas-producing materials (such as plexiglass) to make arc-extinguishing elements. The gas cools and extinguishes the arc. The larger the switching current, the stronger the arc, the more gas decomposed, and the better the arc extinguishing effect.
4. Compressed air ring network cabinet: The compressed air ring network cabinet is named after the compressed air load switch. The compressed air switch uses compressed air to blow the arc. When the brake is opened, the compressed air piston moves rapidly to compress the air in the cylinder. When the arc-extinguishing contact is separated to generate an arc, the compressed gas is blown to the arc through the nozzle to elongate the arc. The low point of the current is extinguished, the compressed air load switch generally transfers the current about 1 kA, and reaches the closing short-circuit current of 50 kA, and the thermal stability current is generally 20 kA for 3 s.
The basic wiring unit of the ring network cabinet
Figure 4 shows the wiring diagram of the simplest fully enclosed ring main unit. The incoming line of the medium voltage feeder is equipped with a load isolation switch, and the transformer is connected to the ring network system through a load switch connected with a current limiting fuse, which not only protects the fault of the transformer, but also isolates the faulty transformer, so that the ring network will not be disconnected. . The cabinet ring network used now is improved and expanded on the basis of the basic wiring unit.
The advantages of ring main unit
1. Prevent misoperation and effectively protect personal and equipment safety
Taking the vacuum ring main unit produced by the Shantou Special Economic Zone Complete Plant as an example, the vacuum load switch used in this product is a high-voltage switchgear with three stations. That is, isolation, closing, and grounding, the isolation switch and the grounding switch have visible fractures, and the load switch and the isolation switch have the function of automatic linkage, that is, when the vacuum load switch is disconnected, the isolation switch is automatically disconnected, forming a visible fracture. When the load switch is closed, the isolating switch automatically closes first; the load switch and grounding switch also have strict requirements.
The so-called "ring main unit" means that each distribution branch is equipped with a switch cabinet (outgoing switch cabinet), and the busbar of this switch cabinet is also a part of the ring trunk. That is to say, the ring trunk is formed by connecting the busbars of each outlet cabinet. Each outlet cabinet is called "Ring Main Unit".
The role of the ring network cabinet
The function of the ring network cabinet is to connect the ring network line and improve the power supply reliability of the line, such as the ring network line closing operation or the ring network line load cutover. Ring network cabinets are used in different parts of the ring network and are slightly different in classification, mainly including incoming ring network cabinets, emergence ring network cabinets and contact ring network cabinets.
The principle of ring network cabinet
It is to realize the mutual supply of lines, that is, after different lines come out from different substations, they will hold hands with each other. Under normal circumstances, the connection will be disconnected, and they will operate separately. , close the connection, and let another substation carry the load originally brought by the original substation. Or a line or substation with a high load, and another with a low load, can selectively disconnect from a contact point, and share a part of the load by the line or substation with a lower load, which not only ensures The reliability of the power supply and the stable operation of the power grid are also ensured.
Structural characteristics of ring main unit
a. The ring network cabinet is composed of four parts: switch room, fuse room, operating mechanism room and cable room (chassis).
b. The switch room is composed of various functional circuits (including earthing switches and load switches) sealed in the metal shell and the bus bars between the circuits. The shell is welded by 3mm cold-rolled steel plate (or non-embroidered steel plate). Each functional circuit includes a load switch and grounding switch. The load switch is composed of a vertically moving moving contact system and a static contact located at the lower end. When the switch is closed, the moving contact moves downward and the load switch is turned on. The grounding switch is composed of a moving contact blade and a static contact blade. During the movement of the spring, the grounding switch is quickly turned on. There are 4 rectangular assembly process holes in the upper and rear of the switch room, and the front of the ring network cabinet is equipped with an observation window, which can see the "off" and "on" positions of the grounding switch. An explosion-proof device is installed at the rear of the ring main unit.
c. The load switch adopts a compressed air blowing structure, which has strong arc extinguishing ability and does not affect the insulation between phases and ground. Both the dynamic and static contacts have arc contacts, which greatly improves the breaking times.
d. The fuse and the load switch room form a transformer protection circuit. The high-voltage current-limiting fuse is installed in the epoxy cast insulating shell. After the fuse is blown, the striker is ejected and the load switch is opened.
e. The operating mechanism room is located on the front of the ring main unit. In each functional circuit, the load switch is equipped with a human (or electric) energy storage spring operating mechanism, and the grounding switch is equipped with a human energy storage spring operating mechanism. They are respectively used for load switch closing operation and manual opening rotary knob and opening and closing operation holes of grounding switch, load switch opening and closing position indicator lights and electric opening and closing buttons, and are equipped with analog lines, switch status Display card and lock position, the operation of load switch and grounding switch has interlocking device to prevent misoperation.
Types of Ring Main Units:
1. Vacuum ring network cabinet: The vacuum ring network cabinet is a new generation of environmentally friendly solid insulation vacuum ring network cabinet products. This product adopts vacuum circuit breaker + microcomputer protection device, and all conductive circuits are wrapped with epoxy resin or silicone rubber. It ensures high safety of operation and operation, and the use voltage level can reach up to 24KV.
2. SF6 ring network cabinet: SF6 ring network cabinet is a combination of air-insulated or gas-insulated medium-voltage electrical appliances with load switch as the core component that can be freely combined into multi-circuit entry and exit with switching, contacting and protecting power system functions. Its main circuit core components are composed of SF6 load switch or additional circuit breakers and other primary auxiliary appliances.
3. Gas-producing ring network cabinet: Gas-producing ring network cabinet is made of solid gas-producing materials (such as plexiglass) to make arc-extinguishing elements. The gas cools and extinguishes the arc. The larger the switching current, the stronger the arc, the more gas decomposed, and the better the arc extinguishing effect.
4. Compressed air ring network cabinet: The compressed air ring network cabinet is named after the compressed air load switch. The compressed air switch uses compressed air to blow the arc. When the brake is opened, the compressed air piston moves rapidly to compress the air in the cylinder. When the arc-extinguishing contact is separated to generate an arc, the compressed gas is blown to the arc through the nozzle to elongate the arc. The low point of the current is extinguished, the compressed air load switch generally transfers the current about 1 kA, and reaches the closing short-circuit current of 50 kA, and the thermal stability current is generally 20 kA for 3 s.
The basic wiring unit of the ring network cabinet
Figure 4 shows the wiring diagram of the simplest fully enclosed ring main unit. The incoming line of the medium voltage feeder is equipped with a load isolation switch, and the transformer is connected to the ring network system through a load switch connected with a current limiting fuse, which not only protects the fault of the transformer, but also isolates the faulty transformer, so that the ring network will not be disconnected. . The cabinet ring network used now is improved and expanded on the basis of the basic wiring unit.
The advantages of ring main unit
1. Prevent misoperation and effectively protect personal and equipment safety
Taking the vacuum ring main unit produced by the Shantou Special Economic Zone Complete Plant as an example, the vacuum load switch used in this product is a high-voltage switchgear with three stations. That is, isolation, closing, and grounding, the isolation switch and the grounding switch have visible fractures, and the load switch and the isolation switch have the function of automatic linkage, that is, when the vacuum load switch is disconnected, the isolation switch is automatically disconnected, forming a visible fracture. When the load switch is closed, the isolating switch automatically closes first; the load switch and grounding switch also have strict requirements.
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JIANGXI KERUI ELECTRIC CO., LTD.
Add：No. 439, No.1 Road, Area A, Xiaolan Economic and Technological Development
Fax：0791-8575 1610