Series fracture vacuum grounding switch device and ring main unit

Abstract

The invention relates to the technical field of gas insulated switch devices, in particular to a series fracture vacuum grounding switch device and a ring main unit. A series connection fracture vacuum grounding switch device comprises a wire inlet end and a wire outlet end, a circuit breaker and a three-position isolation grounding switch are sequentially connected between the wire inlet end and the wire outlet end in series, and the three-position isolation grounding switch comprises an isolation switch static contact seat, a contact knife assembly and a grounding switch assembly. The isolating switch static contact seat is connected with the circuit breaker to form a conductive loop, the grounding switch assembly comprises a grounding contact, and the contact knife assembly is movably arranged between the isolating switch static contact seat and the grounding contact to realize conduction with the isolating switch static contact seat or the grounding contact. The grounding switch assembly further comprises an arc extinguishing breaking device which is closed after the contact knife assembly moves to the grounding contact. The arc extinguishing on-off device of the grounding switch assembly has the arc extinguishing capability, and a circuit breaker does not need to be operated during grounding operation, so that the operation link is simplified, and the misoperation possibility of operation and maintenance operators is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-insulated switchgear, and particularly to a series-break vacuum earthing switchgear and a ring main unit. Background Art

[0002] As an electrical equipment in the distribution network, the ring main unit is an important switching equipment for ring network power supply and terminal power supply. For a long time, the ring main unit has mainly been applied with gas insulation, and the most widely used one is the SF 6 gas-insulated ring main unit. SF 6 gas has very stable chemical properties and excellent insulation and arc extinguishing performances, and is widely applied in power equipment. However, since SF 6 gas has a strong destructive effect on the ozone layer, SF 6 gas will generate SF 4 , S 2 F 2 and other highly toxic substances under the action of a high-temperature arc, which will cause extremely adverse effects on humans and the environment in which they live. The international community has reached a consensus to develop a low-carbon, environment-friendly and green economic industry. In order to protect the environment, it is necessary to abandon the use of SF 6 gas insulation. Nowadays, an environment-friendly gas-insulated ring main unit using dry air or nitrogen as the insulating medium has been developed to replace the SF 6 gas-insulated ring main unit.

[0003] Compared with the SF 6 gas-insulated ring main unit, dry air or nitrogen is a natural gas insulating material, and there are no toxic arc decomposition products, which is a green environment-friendly product that has no impact on the environment. However, dry air and nitrogen do not have the arc extinguishing ability. In practical applications, most of the environment-friendly gas-insulated ring main units adopt an upper isolation three-position switch scheme, and a three-position switch composed of a disconnector and an earthing switch is installed on the upper part of the vacuum circuit breaker, adopting the vacuum arc extinguishing of the circuit breaker and the environment-friendly gas insulation method.

[0004] Such as Figure 1As shown in the figure, the existing upper isolation three-position switch device of the environmentally friendly gas-insulated ring main unit includes a disconnector static contact seat 201, an insulating shaft contact knife assembly 202, a grounding contact 203, and a circuit breaker 204. Among them, the circuit breaker 204 is located downstream of the wiring terminal. The isolation static contact seat 201 is connected to the circuit breaker 204 through a busbar to form a conductive loop. The grounding contact 203 is located above the circuit breaker 204 and is connected to the circuit breaker 204. During the opening operation, the circuit breaker must be opened first. After the circuit breaker is opened, the disconnector is then separated. Then the grounding switch is closed. After the grounding switch is closed, the circuit breaker needs to be closed again to complete the grounding operation. If a short-circuit fault occurs when the grounding switch is closed, the short-circuit fault current for the grounding switch closing is actually completed by the circuit breaker. The circuit breaker has the breaking ability for rated current, overload current, and short-circuit current, which can ensure the reliability of the grounding switch closing. During the closing operation, the circuit breaker must be opened first, then the grounding switch is opened, then the disconnector is closed, and finally the circuit breaker is closed to complete the closing operation.

[0005] For the upper isolation three-position switch device of the environmentally friendly gas-insulated ring main unit, whether it is the closing operation or the opening operation, the circuit breaker needs to be operated twice. The operation is relatively cumbersome, and the anti-misoperation interlocking device is also relatively cumbersome and complex. It is possible for operation and maintenance operators to cause misoperations. Summary of the Invention

[0006] The purpose of the present invention is to provide a series-break vacuum grounding switch device and a ring main unit, which are used to solve the problem that for the existing switch device of the environmentally friendly gas-insulated ring main unit, whether it is the closing operation or the opening operation, the circuit breaker needs to be operated twice. The operation is relatively cumbersome, the anti-misoperation interlocking device is also relatively cumbersome and complex, and it is possible for operation and maintenance operators to cause misoperations.

[0007] The series-break vacuum grounding switch device of the present invention adopts the following technical solutions: A series-break vacuum grounding switch device includes an incoming line end and an outgoing line end. It is characterized in that a circuit breaker and a three-position isolation grounding switch are connected in series between the incoming line end and the outgoing line end. The three-position isolation grounding switch includes a disconnector static contact seat, a contact knife assembly, and a grounding switch assembly. The disconnector static contact seat is connected to the circuit breaker to form a conductive loop. The grounding switch assembly includes a grounding contact. The contact knife assembly is movably arranged between the disconnector static contact seat and the grounding contact to realize conduction with the disconnector static contact seat or the grounding contact. The grounding switch assembly further includes an arc-extinguishing breaking device that closes after the contact knife assembly moves to the grounding contact.

[0008] The series-break vacuum earthing switch device of the present invention improves the existing switch device for an environmentally friendly gas-insulated ring main unit. When the series-break vacuum earthing switch device of the present invention is in use, during the power-off operation of the switchgear, first, the circuit breaker is actuated to trip the circuit breaker. Secondly, the knife contact assembly is driven to rotate, driving the knife contact assembly to rotate to the open position. Finally, the knife contact assembly is driven to rotate, driving the knife contact assembly to rotate and close with the earthing contact. After the knife contact assembly is closed with the earthing contact, the arc-extinguishing opening and closing device is driven to close to complete the closing of the earthing switch, and the power-off operation is completed. During the power-on operation of the switchgear, first, the arc-extinguishing opening and closing device is driven to separate and then the knife contact assembly is driven to rotate, driving the knife contact assembly to rotate to the open position. Secondly, the knife contact assembly is driven to rotate, driving the knife contact assembly to rotate and close with the static contact seat of the disconnector. Finally, the circuit breaker is actuated to close the circuit breaker to complete the closing of the disconnector, and the power-on operation is completed. The arc-extinguishing opening and closing device of the earthing switch assembly has the ability to extinguish arcs, eliminating the need to operate the circuit breaker during earthing operations, simplifying the operation process and avoiding the possibility of misoperation by operation and maintenance personnel.

[0009] Further, a linkage mechanism is provided between the knife contact assembly and the arc-extinguishing opening and closing device, and they are linked through the linkage mechanism and share the same operating mechanism. The knife contact assembly and the arc-extinguishing opening and closing device share one operating mechanism, which saves costs, has a simple structure, and has a good driving effect with the same operating mechanism.

[0010] Further, the arc-extinguishing opening and closing device includes a vacuum switch tube. The vacuum switch tube has excellent arc-extinguishing ability and is environmentally friendly during use.

[0011] Further, the vacuum switch tube includes an insulating housing, a vacuum switch static contact and a vacuum switch moving contact are arranged inside the insulating housing, and the earthing contact is electrically connected to the vacuum switch static contact. Through the electrical connection between the earthing contact and the vacuum switch static contact, the structure is simple and the operation is convenient when realizing the opening and closing actions of the vacuum switch tube.

[0012] Further, the circuit breaker is horizontally arranged below the incoming line end and connected to the incoming line end. The static contact seat of the disconnector is arranged below the circuit breaker and close to one end thereof. The earthing switch assembly is arranged below the circuit breaker and close to the other end thereof. The knife contact assembly is located between the static contact seat of the disconnector and the earthing switch assembly and is driven by a driving mechanism to swing and switch positions. The circuit breaker does not need to be connected to the earthing switch assembly. The upper arrangement is more reasonable, the overall structure is compact and uniform, and the driving process is more stable.

[0013] The ring main unit of the present invention adopts the following technical solution: A ring main unit includes a cabinet body, and a series-break vacuum earthing switch device is arranged inside the cabinet body. The series-break vacuum earthing switch device includes an incoming line end and an outgoing line end. A circuit breaker and a three-position isolating earthing switch are sequentially connected in series between the incoming line end and the outgoing line end. The three-position isolating earthing switch includes an isolating switch static contact seat, a moving contact blade assembly, and an earthing switch assembly. The isolating switch static contact seat is connected to the circuit breaker to form a conductive loop. The earthing switch assembly includes an earthing contact. The moving contact blade assembly is movably arranged between the isolating switch static contact seat and the earthing contact to realize conduction with the isolating switch static contact seat or the earthing contact. The earthing switch assembly further includes an arc-extinguishing opening and closing device that closes after the moving contact blade assembly moves to the earthing contact.

[0014] The ring main unit of the present invention improves the existing ring main unit. When the ring main unit of the present invention is in use, the series-break vacuum earthing switch device is installed inside the cabinet body. When the switchgear performs a power-off operation, first, operate the circuit breaker to trip the circuit breaker. Second, drive the moving contact blade assembly to rotate, driving the moving contact blade assembly to rotate to the open position. Finally, drive the moving contact blade assembly to rotate, driving the moving contact blade assembly to close with the earthing contact. After the moving contact blade assembly closes with the earthing contact, drive the arc-extinguishing opening and closing device to close to complete the closing of the earthing switch, and the power-off operation is completed. When the switchgear performs a power-on operation, first, drive the arc-extinguishing opening and closing device to separate and then drive the moving contact blade assembly to rotate, driving the moving contact blade assembly to rotate to the open position. Second, drive the moving contact blade assembly to rotate, driving the moving contact blade assembly to close with the isolating switch static contact seat. Finally, operate the circuit breaker to close the circuit breaker to complete the closing of the isolating switch, and the power-on operation is completed. The arc-extinguishing opening and closing device of the earthing switch assembly has the ability to extinguish arcs, eliminating the need to operate the circuit breaker during earthing operations, simplifying the operation process, and avoiding the possibility of misoperation by operation and maintenance personnel.

[0015] Further, a linkage mechanism is provided between the moving contact blade assembly and the arc-extinguishing opening and closing device, and they are linked through the linkage mechanism and share the same operating mechanism. The moving contact blade assembly and the arc-extinguishing opening and closing device share one operating mechanism, which saves costs, has a simple structure, and has a good driving effect with the same operating mechanism.

[0016] Further, the arc-extinguishing opening and closing device includes a vacuum switch tube. The vacuum switch tube has excellent arc-extinguishing ability and is environmentally friendly during use.

[0017] Further, the vacuum switch tube includes an insulating housing, a vacuum switch static contact and a vacuum switch moving contact are arranged inside the insulating housing, and the earthing contact is conductively connected to the vacuum switch static contact. Through the conductive connection between the earthing contact and the vacuum switch static contact, the structure is simple and the operation is convenient when realizing the opening and closing actions of the vacuum switch tube.

[0018] Further, a switch frame is provided inside the cabinet. The incoming line terminal is arranged above the switch frame, and the outgoing line terminal is arranged below the switch frame. The circuit breaker is horizontally arranged at the upper part of the switch frame and is connected to the incoming line terminal above. One end of the circuit breaker is fixedly installed on the switch frame. The static contact seat of the disconnecting switch is arranged at one end of the lower side of the circuit breaker away from the fixed installation. The earthing switch assembly is arranged at the lower side of the circuit breaker and close to the fixed installation end of the circuit breaker. The knife contact assembly is arranged on the switch frame between the static contact seat of the disconnecting switch and the earthing switch assembly and is driven by a driving mechanism to swing and switch positions. The arrangement of each device on the switch frame ensures the structural stability. The circuit breaker does not need to be connected to the earthing switch assembly, and the arrangement in the upper part is more reasonable. The overall structure is compact and uniform, and the driving process is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of a switch device for an existing environmentally friendly gas-insulated ring main unit;

[0020] Figure 2 is a schematic structural diagram of Embodiment 1 of the ring main unit of the present invention;

[0021] Figure 3 is Figure 2 side view of;

[0022] Figure 4 is a schematic structural diagram of Embodiment 1 of the series-break vacuum earthing switch device of the present invention in the closing position;

[0023] Figure 5 is a schematic structural diagram of Embodiment 1 of the series-break vacuum earthing switch device of the present invention in the opening position;

[0024] Figure 6 is a schematic structural diagram of Embodiment 1 of the series-break vacuum earthing switch device of the present invention in the earthing position;

[0025] Figure 7 is a schematic structural diagram of the closing position of the vacuum switch tube of Embodiment 1 of the series-break vacuum earthing switch device of the present invention;

[0026] Figure 8 is a schematic structural diagram of the switch frame of Embodiment 1 of the ring main unit of the present invention;

[0027] In the figure: 201, isolating switch static contact seat; 202, insulating shaft contact knife assembly; 203, grounding contact; 204, circuit breaker; 101, isolating switch static contact seat; 102, contact knife assembly; 103, earthing switch assembly; 104, circuit breaker; 105, linkage mechanism; 110, incoming line terminal; 120, outgoing line terminal; 1, switch frame; 2, grounding contact; 3, vacuum switch tube; 4, flexible connection; 5, pull rod; 6, grounding busbar; 7, grounding rotating shaft; 8, post insulator; 9, moving contact; 10, contact knife; 11, circuit breaker installation position; 12, circuit breaker rotating shaft installation hole; 13, isolating switch static contact seat installation position; 14, insulating shaft installation hole; 15, grounding rotating shaft installation hole; 16, earthing switch assembly installation position. Detailed implementation mode

[0028] The features and performance of the present invention will be further described in detail below in conjunction with embodiments.

[0029] Specific embodiment 1 of the ring main unit of the present invention:

[0030] The ring main unit of the present invention is as Figure 2-8 shown. A ring main unit includes a cabinet body. A switch frame 1 is arranged in the cabinet body. A series-break vacuum earthing switch device is arranged on the switch frame 1. The series-break vacuum earthing switch device includes an incoming line terminal 110 and an outgoing line terminal 120. The incoming line terminal 110 is arranged above the switch frame 1, and the outgoing line terminal 120 is arranged below the switch frame 1. A circuit breaker 104 and a three-position isolating earthing switch are connected in series between the incoming line terminal 110 and the outgoing line terminal 120 in sequence. The three-position isolating earthing switch includes an isolating switch static contact seat 101, a contact knife assembly 102, and an earthing switch assembly 103.

[0031] As Figure 2 shown, the circuit breaker 104 is arranged in the upper part of the switch frame 1 and below the incoming line terminal 110. The circuit breaker 104 is horizontally arranged and connected to the incoming line terminal 110 above the upper part of the switch frame 1. The other end of the circuit breaker 104 is fixedly installed at the circuit breaker installation position 11 of the switch frame 1. The circuit breaker 104 includes a circuit breaker rotating shaft, and the circuit breaker rotating shaft is installed in the circuit breaker rotating shaft installation hole 12. The isolating switch static contact seat 101 is installed at the isolating switch static contact seat installation position 13 of the switch frame 1, at one end of the lower side of the circuit breaker 104 and far from the circuit breaker installation position 11. The isolating switch static contact seat 101 is connected to the circuit breaker 104 through a conductive busbar to form a conductive loop. The contact knife assembly 102 is installed on the lower side of the switch frame 1 where the isolating switch static contact seat 101 is located. The earthing switch assembly 103 is installed at one end of the lower side of the switch frame 1 where the circuit breaker 104 is located and close to the circuit breaker installation position 11. The contact knife assembly 102 is connected to the outgoing line terminal 120 below. A linkage mechanism 105 is arranged behind the contact knife assembly 102 and the earthing switch assembly 103.

[0032] Specifically, the earthing switch assembly 103 includes an earthing contact 2, a vacuum switch tube 3, a flexible connection 4, a pull rod 5, an earthing busbar 6 and an earthing rotating shaft 7. The vacuum switch tube 3 includes an insulating housing, and a vacuum switch static contact and a vacuum switch moving contact are arranged inside the insulating housing. The earthing contact 2 is electrically connected to the vacuum switch static contact. The earthing contact 2 and the vacuum switch tube 3 are hermetically sealed together through the insulating housing and fixed on the earthing switch assembly installation position 16 of the switch frame 1. A pull rod 5 is connected to the vacuum switch moving contact. The pull rod 5 passes through the flexible connection 4, fixes and presses one end of the flexible connection 4 to the lower end face of the vacuum switch tube 3, and the other end of the flexible connection 4 is fixed together with the earthing busbar 6. The lower end of the pull rod 5 is connected to the crank arm on the earthing rotating shaft 7 through a pin. The earthing rotating shaft 7 is installed in the earthing rotating shaft installation hole 15 of the switch frame 1.

[0033] In this embodiment, the knife contact assembly 102 is fixed to the switch frame 1 through one end of a post insulator 8. The knife contact assembly 102 includes a moving contact 9. The moving contact 9 is fixed on the other end face of the post insulator 8. The moving contact 9 includes a knife contact 10 and an insulating shaft. The insulating shaft is installed on the switch frame 1 through an insulating shaft installation hole 14. One end of the knife contact 10 is connected to the insulating shaft through a pin. The knife contact 10 is swingably arranged between the disconnector static contact seat 101 and the earthing switch assembly. The rotation of the insulating shaft can drive the rotation of the knife contact 10 to perform switch closing and opening operations. The linkage mechanism 105 drives the movement of the insulating shaft of the knife contact assembly 102 and the earthing rotating shaft 7 of the earthing switch assembly 103.

[0034] When the series-break vacuum earthing switch device for an environmentally friendly gas-insulated ring main unit of the present invention is in use, as Figure 4-7 shown, the circuit breaker 104 is in the closing position, and the knife contact 10 of the knife contact assembly 102 is closed with the disconnector static contact seat 101. When the switchgear needs to perform a power-off operation, first rotate the circuit breaker rotating shaft on the circuit breaker 104 to open the circuit breaker 104, then the linkage mechanism 105 drives the rotation of the knife contact assembly 102, driving the knife contact 10 to rotate to the opening position. Finally, the linkage mechanism 105 drives the rotation of the knife contact assembly 102, driving the knife contact 10 to rotate until the knife contact 10 is closed with the earthing contact 2. After the knife contact 10 is closed with the earthing contact 2, the earthing switch assembly starts to close. The linkage mechanism 105 drives the rotation of the earthing rotating shaft 7 to drive the pull rod 5 to move upward, pushing the vacuum switch tube 3 to close to complete the earthing switch closing and power-off operation.

[0035] When the switchgear needs to be energized, first, the linkage mechanism 105 drives the grounding rotating shaft 7 to rotate, driving the pull rod 5 to move downward, pulling the vacuum switch tube 3 to separate to complete the opening of the grounding switch. Then, the linkage mechanism 105 drives the knife contact assembly 102 to rotate, driving the knife contact 10 to leave the grounding contact 2 and rotate to the open position. Finally, the linkage mechanism 105 drives the knife contact assembly 102 to rotate, driving the knife contact 10 to rotate until the knife contact 10 is closed with the isolating switch static contact seat 101, and rotating the circuit breaker rotating shaft on the circuit breaker 104 to close the circuit breaker 104 to achieve circuit conduction, and the power-on operation is completed.

[0036] Through the above description of the specific embodiment 1 of the series-break vacuum grounding switch device of the present invention, it can be seen that in the series-break vacuum grounding switch device of the present invention, the circuit breaker is arranged upstream of the incoming line end, and a vacuum switch tube is provided in the grounding switch assembly. The vacuum switch tube has the arc extinguishing ability, and there is no need to operate the circuit breaker when grounding is not required, which simplifies the operation process and avoids the possibility of misoperation by operation and maintenance operators.

[0037] Of course, the ring main unit of the present invention is not limited to the above embodiment. The following also lists several other implementation manners of the ring main unit based on the design concept of the present invention.

[0038] For example, in other implementation manners, different from the above embodiment 1, the arc extinguishing opening device is an SF 6 type switch device. The SF 6 gas has the arc extinguishing ability, and the gas in other parts of the entire ring main unit is an environmental protection gas.

[0039] For another example, in other implementation manners, different from the above embodiment 1, the knife contact assembly and the arc extinguishing opening and closing device are respectively provided with independent operating mechanisms, and the transmission structure between the independent operating mechanisms and each component is simple.

[0040] Or in other implementation manners, different from the above embodiment 1, the grounding contact partially extends into the insulating housing, and the grounding contact simultaneously constitutes the static contact of the vacuum switch, and the static contact of the vacuum switch is no longer separately provided.

[0041] Or in other implementation manners, different from the above embodiment 1, the contact assembly is directly arranged between the isolating switch static contact seat and the grounding switch assembly, and the circuit breaker, the isolating switch static contact seat, the knife contact assembly, and the grounding switch assembly are in the same vertical direction.

[0042] The embodiments of the series-break vacuum grounding switch device of the present invention are the same as those of the series-break vacuum grounding switch device in the above ring main unit, so no further description will be given.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. The patent protection scope of the present invention shall be subject to the claims. Any equivalent structural changes made by using the content of the specification and drawings of the present invention shall similarly be included in the protection scope of the present invention.

Claims

1. A series-break vacuum earthing switch device, comprising an incoming line terminal (110) and an outgoing line terminal (120). Characterized in that, A circuit breaker (104) and a three-position isolating earthing switch are connected in series between the incoming line terminal (110) and the outgoing line terminal (120). The three-position isolating earthing switch includes an isolating switch static contact seat (101), a moving contact blade assembly (102), and an earthing switch assembly (103). The isolating switch static contact seat (101) is connected to the circuit breaker (104) to form a conductive loop. The earthing switch assembly (103) includes an earthing contact (2). The moving contact blade assembly (102) is movably arranged between the isolating switch static contact seat (101) and the earthing contact (2) to achieve conduction with the isolating switch static contact seat (101) or the earthing contact (2). The earthing switch assembly (103) further includes an arc-extinguishing opening and closing device that closes after the moving contact blade assembly (102) moves to the earthing contact (2).

2. The series-break vacuum earthing switch device according to claim 1, Characterized in that, A linkage mechanism (105) is provided between the moving contact blade assembly (102) and the arc-extinguishing opening and closing device, and they are linked through the linkage mechanism (105) and share the same operating mechanism.

3. The series-break vacuum earthing switch device according to claim 1, Characterized in that, The arc-extinguishing opening and closing device includes a vacuum switch tube (3).

4. The series-break vacuum earthing switch device according to claim 3, Characterized in that, The vacuum switch tube (3) includes an insulating housing. A vacuum switch static contact and a vacuum switch moving contact (9) are arranged inside the insulating housing. The earthing contact (2) is conductively connected to the vacuum switch static contact.

5. The series-break vacuum earthing switch device according to any one of claims 1-4, Characterized in that, The circuit breaker (104) is horizontally arranged below the incoming line terminal (110) and is connected to the incoming line terminal (110). The isolating switch static contact seat (101) is located below the circuit breaker (104) and is arranged near one end thereof. The earthing switch assembly (103) is located below the circuit breaker (104) and is arranged near the other end thereof. The moving contact blade assembly (102) is located between the isolating switch static contact seat (101) and the earthing switch assembly (103) and is driven by a driving mechanism to swing and switch positions.

6. A ring main unit, comprising a cabinet body, and a series-break vacuum earthing switch device is arranged inside the cabinet body. Characterized in that, The series-break vacuum earthing switch device includes an incoming line terminal (110) and an outgoing line terminal (120). A circuit breaker (104) and a three-position isolating earthing switch are connected in series between the incoming line terminal (110) and the outgoing line terminal (120). The three-position isolating earthing switch includes a disconnector static contact seat (101), a moving contact blade assembly (102), and an earthing switch assembly (103). The disconnector static contact seat (101) is connected to the circuit breaker (104) to form a conductive loop. The earthing switch assembly (103) includes an earthing contact (2). The moving contact blade assembly (102) is movably arranged between the disconnector static contact seat (101) and the earthing contact (2) to achieve conduction with the disconnector static contact seat (101) or the earthing contact (2). The earthing switch assembly (103) further includes an arc extinguishing and opening device that closes after the moving contact blade assembly (102) moves to the earthing contact (2).

7. The ring main unit according to claim 6, characterized in that, a linkage mechanism (105) is provided between the moving contact blade assembly (102) and the arc extinguishing and opening device and they are linked by the linkage mechanism (105) and share the same operating mechanism.

8. The ring main unit according to claim 6, characterized in that, the arc extinguishing and opening device includes a vacuum switch tube (3).

9. The ring main unit according to claim 8, characterized in that, the vacuum switch tube (3) includes an insulating housing. A vacuum switch static contact and a vacuum switch moving contact (9) are arranged inside the insulating housing. The earthing contact (2) is conductively connected to the vacuum switch static contact.

10. The ring main unit according to any one of claims 6-9, characterized in that, a switch frame (1) is arranged inside the cabinet. The incoming line terminal (110) is arranged above the switch frame (1), and the outgoing line terminal (120) is arranged below the switch frame (1). The circuit breaker (104) is horizontally arranged on the upper part of the switch frame (1) and is connected to the incoming line terminal (110) above. One end of the circuit breaker (104) is fixedly installed on the switch frame (1). The disconnector static contact seat (101) is arranged at the end of the lower side of the circuit breaker (104) far from the fixedly installed end of the circuit breaker (104). The earthing switch assembly (103) is arranged at the lower side of the circuit breaker (104) and close to the fixedly installed end of the circuit breaker (104). The moving contact blade assembly (102) is arranged on the switch frame (1) between the disconnector static contact seat (101) and the earthing switch assembly (103) and is driven by a driving mechanism to swing and switch positions.

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