A compact center-mounted ring main unit

Abstract

The present invention relates to a compact center-mounted ring network cabinet in the technical field of switchgear, comprising a cabinet body, wherein the cabinet body cavity is provided with two horizontal partitions at upper and lower intervals, so that the cabinet body cavity is divided into an upper chamber, a middle chamber and a lower chamber from top to bottom; the chambers on the same layer are provided with vertical partitions, so that the upper chamber is divided into a metering chamber and a busbar chamber from front to back, the middle chamber is divided into a circuit breaker chamber and a connection chamber from front to back, and the lower chamber is divided into an auxiliary equipment chamber and a cable chamber from front to back; the present invention optimizes the internal space layout, so that the structure is more compact, so as to reduce the front and rear dimensions and reduce the production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of switchgear, and in particular to a compact medium - placed ring main unit (RMU). Background Art

[0002] The medium - placed RMU, also known as the medium - placed cabinet, is short for the armored medium - placed draw - out switchgear. It belongs to the high - voltage distribution device, with a maximum operating voltage of 3.6 / 7.2 / 12 kV, and is an indoor complete set of distribution devices for a three - phase AC 50 Hz single - bus sectionalized system or double - bus sectionalized system. It is mainly used for the power transmission of power plants and small and medium - sized generators, the power reception and transmission of secondary substations in the power system, the power distribution of industrial and mining enterprises and institutions, and the starting of large - scale high - voltage motors, etc.

[0003] The medium - placed RMU in the prior art generally consists of a frame, planar side plates and planar partitions fixedly installed between the frames through bolts / rivets, etc., and a cabinet door installed between the frames through hinges. The cabinet chambers are generally divided into a cable chamber, an auxiliary equipment chamber, a bus chamber, a circuit breaker chamber and a metering chamber.

[0004] The medium - placed RMU in the prior art, as Figure 1 shown, the inner cavity of the cabinet has vertical partitions and horizontal partitions, which divide the inner cavity of the cabinet into a circuit breaker chamber in the upper front, a bus chamber in the upper rear, an auxiliary equipment chamber in the lower front and a cable chamber in the lower rear. A metering chamber is provided in the upper front of the circuit breaker chamber, and the top of the metering chamber is higher than the bus chamber. A contact box with static contacts is provided on one side of the vertical partition corresponding to the bus chamber. Inside the circuit breaker chamber, the dynamic contacts of the circuit breaker are inserted into or pulled out of the static contacts by means of a trolley push - pull method. The general size of this structure of the medium - placed RMU is 1500 / 1660*800*2300 mm.

[0005] In the prior art, the center-mounted ring main unit is provided with a track for the movement of the trolley at the bottom of the circuit breaker chamber (on the upper surface of the horizontal partition) to ensure that the moving contact of the circuit breaker can be accurately matched with the static contact when the trolley is pushed. After the moving contact of the circuit breaker is matched with the static contact, the position of the trolley is fixed by a locking structure. However, the quick pull-out and quick plug-in of the moving contact and the static contact in the center-mounted ring network cabinet of the prior art only rely on manual experience, and the pull-out speed is often slow, and the insertion collision occurs (the circuit breaker trolley collides with the cabinet); and the busbar and the contacts of the corresponding circuit breaker in the existing center-mounted ring network cabinet are connected by the connection between bolts and the line bar, and the wiring position of the line bar is fixed by insulators, which makes subsequent maintenance work (for example, insulators may age, crack, and be dirty after long-term use. These problems may affect the insulation performance of the insulator and even cause failures. Therefore, regular inspections are required to avoid accidents. When repairing the insulators, since the insulators are located in the cabinet, the maintenance equipment needs to be extended into the cabinet and bypass the line bar to perform specific maintenance) is difficult.

[0006] For this purpose, we designed a compact center-mounted ring main unit. Summary of the invention

[0007] In order to overcome the deficiencies in the background technology, the present invention discloses a compact center-mounted ring main unit.

[0008] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0009] A compact center-mounted ring network cabinet comprises a cabinet body, wherein the cabinet body cavity is separated by two horizontal partitions at the upper and lower parts, so that the cabinet body cavity is divided into an upper chamber, a middle chamber and a lower chamber from top to bottom; the chambers on the same layer are provided with vertical partitions, so that the upper chamber is divided into a metering chamber and a busbar chamber from front to back, the middle chamber is divided into a circuit breaker chamber and a connection chamber from front to back, and the lower chamber is divided into an auxiliary equipment chamber and a cable chamber from front to back.

[0010] Preferably, the busbars in the busbar chamber are arranged in the same horizontal plane, so that the height of the busbar chamber is consistent with the height of the metering chamber.

[0011] Preferably, a track is provided at the bottom of the circuit breaker chamber to facilitate the operation of pulling out the circuit breaker trolley from the circuit breaker chamber.

[0012] Preferably, the wiring room is provided with tracks and a wiring trolley that can move on the tracks, so as to facilitate the operation of pulling out the wiring trolley from the wiring room.

[0013] Preferably, an insulator connected to the line bar entering the busbar chamber is installed on the upper part of the rear side plate of the wiring trolley, and an insulator connected to the line bar entering the cable chamber is installed on the lower part.

[0014] Preferably, the front side plate of the wiring trolley is provided with a contact box having a static contact, and the opening of the contact box faces the circuit breaker chamber to facilitate the plug-in cooperation between the moving contact and the static contact of the circuit breaker.

[0015] Preferably, the busbars of the wiring trolley are connected to corresponding busbars via plug-in connectors; wherein a portion of the plug-in connector is correspondingly installed on the wiring trolley, and another portion is installed on the cabinet.

[0016] Preferably, a notch is provided in the middle of the track along the width direction, and the width of the notch is smaller than the width of the wheel of the corresponding trolley close to the corresponding vertical partition.

[0017] Preferably, a power-assisting structure is provided in the notch area of ​​the track to assist the wheel movement of the corresponding trolley close to the corresponding vertical partition.

[0018] Preferably, the power-assisting structure comprises:

[0019] The power-assisting rod comprises a vertical portion, a limiting portion, and a connecting portion connecting the lower end of the vertical portion with the lower end of the limiting portion, wherein the connecting portion is connected to a hinge seat through a pin shaft, and the hinge seat is arranged below the track;

[0020] A tension spring, one end of which is arranged at the upper end of the vertical part, and the other end is arranged at the bottom of the bracket, and the bracket is arranged below the track, so as to change the pulling rotation direction of the power-assisting rod by changing the position between the pins;

[0021] A limiting member is provided below the limiting portion corresponding to the notch and is used to limit the rotation angle of the power assist lever;

[0022] Wherein, the vertical portion contacts the corresponding side wall of the notch.

[0023] Due to the adoption of the above-mentioned technical solution, the present invention has the following beneficial effects:

[0024] 1. The internal space layout is optimized to make the structure more compact, thus reducing the front and rear dimensions and reducing the production cost;

[0025] 2. The busbars in the busbar room were rearranged to ensure the consistency of height between the busbar room and the metering room, effectively preventing the overall height from increasing and improving space utilization;

[0026] 3. The setting of the wiring trolley can provide a larger inspection space by pulling out the wiring trolley, which is convenient for inspection without obstruction of the wire row and simplifies the maintenance process;

[0027] 4. The setting of the power-assisting structure can enhance the convenience and safety of operation through mechanical assistance, and can better realize the "quick pull" operation of the static contact and the moving contact, as well as the plug-in connector. It also has a certain buffering effect when the "quick plug" operation is about to end. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a center-mounted ring main unit in the prior art;

[0029] Figure 2 It is a structural schematic diagram of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of the pull-out wiring trolley of the present invention;

[0031] Figure 4 This is a schematic diagram of the structure of the circuit breaker trolley pulled out according to the present invention;

[0032] Figure 5 The coordination between the wiring trolley and the circuit breaker trolley in the present invention;

[0033] Figure 6 It is a partial schematic diagram of the trolley, track and power-assisting structure in the present invention;

[0034] Figure 7 This is a schematic diagram of the coordination of the trolley, the track and the power-assisting structure in the first posture of the present invention;

[0035] Figure 8 It is a schematic diagram of the coordination of the trolley, the track and the power-assisting structure in the second posture of the present invention;

[0036] Fig. 9 This is a schematic diagram of the coordination of the trolley, track and power-assisting structure in the third posture of the present invention.

[0037] In the figure: 1. cabinet; 11. horizontal partition; 12. vertical partition; 101. metering room; 102. busbar room; 103. circuit breaker room; 104. connection room; 105. auxiliary equipment room; 106. cable room; 2. busbar; 3. contact box; 4. static contact; 5. circuit breaker moving contact; 6. track; 61. notch; 7. circuit breaker trolley; 8. power assist structure; 81. power assist rod; 811. vertical part; 812. limit part; 813. connection part; 82. hinge seat; 83. pin shaft; 84. tension spring; 85. limit piece; 86. bracket; 9. wiring trolley; 91. insulator; 92. plug-in connector; 93. line bar. DETAILED DESCRIPTION

[0038] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "back", "left", "right", etc. indicating directions or positional relationships, they only correspond to the drawings of the present application and are for the convenience of describing the present invention; it should be understood that if there are terms such as "end", "side", "end portion", "lateral", "lateral", "transverse", "longitudinal", etc. indicating directions or positional relationships, they only correspond to the length and width of the corresponding components, that is, the "end portion" indicates the head and tail areas in the length direction of the corresponding component, and the "side portion" indicates the head and tail areas in the width direction of the corresponding component; this is for the convenience of describing the present invention and is not to indicate or imply that the device or element referred to must have a specific direction.

[0039] Embodiment 1, in combination with the attached Figure 2 and 4 A compact center-mounted ring main unit comprises a cabinet 1, wherein the inner cavity of the cabinet 1 is separated by two horizontal partitions 11 from top to bottom, so that the inner cavity of the cabinet 1 is divided into an upper chamber, a middle chamber and an upper chamber from top to bottom; the chambers on the same layer are provided with vertical partitions 12, so that the upper chamber is divided into a metering chamber 101 and a busbar chamber 102 from front to back, the middle chamber is divided into a circuit breaker chamber 103 and a connection chamber 104 from front to back, and the lower chamber is divided into an auxiliary equipment chamber 105 and a cable chamber 106 from front to back.

[0040] The busbar chamber 102 is located in the upper chamber. Compared with the prior art center-mounted ring main cabinet in which the circuit breaker chamber 103 and the busbar chamber 102 are located in the same chamber, the center-mounted ring main cabinet can effectively reduce the front and rear dimensions.

[0041] It should be noted that: since the components and layout in the auxiliary equipment room 105, the cable room 106 and the metering room 101 adopt the existing technology, they are not described in detail here.

[0042] The busbars 2 in the busbar chamber 102 are all arranged in the same horizontal plane, so that the height of the busbar chamber 102 is consistent with the height of the metering chamber 101. Compared with the center-mounted ring main unit in the prior art in which the metering chamber 101 is located in the upper front position of the circuit breaker chamber 103, the height space of the busbar chamber 102 and the circuit breaker chamber 103 in the center-mounted ring main unit does not change.

[0043] Therefore, compared with the centrally mounted ring main unit in the prior art, the front and rear dimensions of the centrally mounted ring main unit can be reduced, thereby reducing the manufacturing cost of the cabinet body 1 .

[0044] In this example, the center-mounted ring main unit can achieve a size of 1100*800*2300mm.

[0045] A contact box 3 is installed on one side of the middle vertical partition 12 corresponding to the connection chamber 104. The contact box 3 has a static contact 4 inside, and the opening of the contact box 3 faces the circuit breaker chamber 103, so that the circuit breaker moving contact 5 and the static contact 4 can be plugged in and out.

[0046] A track 6 is provided at the bottom of the circuit breaker chamber 103, that is, the track 6 is provided on the upper surface of the horizontal partition 11 below. The circuit breaker trolley 7 moves on the track 6 to realize the operation of pulling out the circuit breaker from the circuit breaker chamber 103, which is convenient for the maintenance of the circuit breaker. At the same time, this method also realizes the plugging and unplugging operation of the moving contact 5 and the static contact 4 of the circuit breaker.

[0047] Embodiment 2, combined with the attached Figure 3 and 5 -9, a compact mid-mounted ring main unit, based on the first embodiment, in order to meet the "quick plug and pull" action when the moving contact 5 of the circuit breaker cooperates with the static contact 4; a notch 61 is provided in the middle of the track 6 along the width direction corresponding to the position of the rear wheel of the circuit breaker trolley 7, and the width of the notch 61 is smaller than the width of the rear wheel of the circuit breaker trolley 7, that is, the rear wheel of the circuit breaker trolley 7 can roll smoothly in the notch 61 area of ​​the track 6 without up and down bumps. Preferably, the width of the notch 61 is 1 / 4 to 1 / 3 of the width of the rear wheel of the circuit breaker trolley 7, and the notch 61 area of ​​the track 6 is provided with a power assist structure 8 corresponding to the rear wheel of the circuit breaker trolley 7.

[0048] For ease of understanding, the assist structure 8 is described in detail in the following manner in which the moving contact 5 and the stationary contact 4 of the circuit breaker cooperate with each other. Figure 6-7 ,as follows:

[0049] The power-assisting structure 8 includes a power-assisting rod 81, which has a vertical portion 811 that contacts the rear side of the rear wheel of the circuit breaker trolley 7, a limiting portion 812 that contacts the bottom of the front side of the rear wheel of the circuit breaker trolley 7, and a connecting portion 813 that connects the lower end of the vertical portion 811 with the lower end of the limiting portion 812. The vertical portion 811 contacts the rear side wall of the notch 61; the connecting portion 813 is correspondingly hinged to the track 6. Furthermore, a hinge seat 82 is provided at the bottom of the track 6, and the connecting portion 813 is hinged to the track 6 through a pin 83.

[0050] The assisting structure 8 also includes a tension spring 84 and a limiting member 85 for limiting the angle of the assisting rod 81 . The upper end of the tension spring 84 is connected to the upper end of the vertical portion 811 , and the lower end of the tension spring 84 is connected to a bracket 86 installed at the bottom of the track 6 ; the limiting member 85 is arranged below the front side of the notch 61 .

[0051] It should be noted that: when the moving contact 5 and the stationary contact 4 of the circuit breaker are in the coordinated posture, Figure 7As shown, the central axis of the tension spring 84 is located behind the central axis of the pin shaft 83, that is, the effect of the tension spring 84 on the booster rod 81 makes the booster rod 81 have a tendency to flip counterclockwise; when the moving contact 5 of the circuit breaker is separated from the static contact 4, as shown in FIG. Fig. 9 As shown, the limiting portion 812 abuts against the limiting member 85, and the central axis of the tension spring 84 is located in front of the central axis of the pin shaft 83, that is, the effect of the tension spring 84 on the assisting rod 81 makes the assisting rod 81 have a tendency to flip clockwise.

[0052] Specifically, when the limiting portion 812 contacts the limiting member 85 , the top of the limiting portion 812 is lower than the top surface of the track 6 .

[0053] When the circuit breaker trolley 7 needs to be pulled forward, Figure 7 As shown, at this time, the effect of the tension spring 84 on the booster rod 81 makes the booster rod 81 have a counterclockwise flipping tendency. Pulling the circuit breaker trolley 7 needs to overcome the tension of the tension spring 84, and the rear wheel of the circuit breaker trolley 7 squeezes the limit portion 812 to make the booster rod 81 rotate clockwise; when the circuit breaker moving contact 5 and the static contact 4 are separated by a certain distance A (the circuit breaker trolley 7 is pulled out of the distance A), and before they are completely separated, as shown in FIG. Figure 8 As shown, due to the clockwise rotation of the power-assisting rod 81, the top of the limiting portion 812 is lower than the top surface of the track 6. At this time, the tension spring 84 rotates because the upper end follows the rotation of the upper end of the vertical portion 811, and the central axis passes the position of the central axis of the pin shaft 83. At this time, the action of the tension spring 84 on the power-assisting rod 81 makes the power-assisting rod 81 have a tendency to flip clockwise. Therefore, the vertical portion 811 applies a forward force to the rear wheel of the circuit breaker trolley 7, which can speed up the movement of the circuit breaker trolley 7 and achieve a "quick pull" effect.

[0054] That is to say, the separation of the moving contact 5 and the static contact 4 of the circuit breaker can be divided into three actions. The first action is: when the position of the circuit breaker trolley 7 changes from 0 to A, the rear wheel of the circuit breaker trolley 7 squeezes the limit part 812, so that the power-assisting rod 81 overcomes the tension of the tension spring 84 and rotates clockwise. This stage is the power accumulation stage, that is, in this stage, the force used by the operator to pull the circuit breaker trolley 7 is greater than the normal force of pulling the circuit breaker trolley 7. The second action is: during the process of the position of the circuit breaker trolley 7 changing from A to B, since the rear wheel of the circuit breaker trolley 7 is no longer blocked by the limiting part 812, the stored force in the first stage is released, and the tension of the tension spring 84 causes the power rod 81 to rotate clockwise, so that the vertical part 811 pushes the rear wheel of the circuit breaker trolley 7 forward, accelerating the moving speed of the circuit breaker trolley 7. This stage is the power stage, that is, the force required by the operator to pull the circuit breaker trolley 7 in this stage is less than the force of normally pulling the circuit breaker trolley 7. However, affected by the first stage, the actual force required by the operator to pull the circuit breaker trolley 7 in this stage is also greater than the force of normally pulling the circuit breaker trolley 7, and combined with the vertical part 811, the rear wheel of the circuit breaker trolley 7 is pushed forward, thereby achieving the effect of acceleration. The third action is: then the rear wheel of the circuit breaker trolley 7 is separated from the vertical part 811, and under the action of inertia, the position of the circuit breaker trolley 7 changes from B to C, so that the circuit breaker moving contact 5 and the static contact 4 are completely separated.

[0055] When the circuit breaker trolley 7 needs to be pushed backward, Fig. 9 As shown, at this time, the effect of the tension spring 84 on the assist rod 81 makes the assist rod 81 have a tendency to flip clockwise. When the position of the circuit breaker trolley 7 moves to B, the rear wheel of the circuit breaker trolley 7 passes over the limit portion 812 and contacts the vertical portion 811. Figure 8 As shown in FIG. 1 , the rear wheel of the circuit breaker trolley 7 begins to squeeze the vertical portion 811, causing the booster rod 81 to overcome the tension of the tension spring 84 and rotate counterclockwise until the booster rod 81 returns to the 0 position, as shown in FIG. Figure 7 As shown in the posture, in the rear section where the moving contact 5 of the circuit breaker is plugged into the static contact 4, the vertical portion 811 abuts against the rear wheel of the circuit breaker trolley 7, and the rear wheel of the circuit breaker trolley 7 overcomes the tension spring 84 and moves, thereby reducing the moving speed of the circuit breaker trolley 7 and preventing strong collisions.

[0056] That is to say, the effective plug-in matching length L between the static contact 4 and the circuit breaker moving contact 5 is the distance between the position C and the position 0.

[0057] It should be noted that: in order to show the positional relationship between the tension spring 84 and the pin 83 more obliquely, the attached Figure 7-9 The middle tension spring 84 is shown with only its central axis.

[0058] Embodiment 3, in combination with the attached Figure 2 and 5-9, a compact mid-mounted ring main unit, based on the first embodiment, in order to facilitate the detection of the insulator 91 used to fix the local position of the line row 93, the connection room 104 is provided with a pull-out wiring trolley 9.

[0059] Furthermore, the upper and lower side walls and the front side wall (the vertical partition 12 of the middle chamber) of the connection chamber 104 are provided with fractures, wherein the upper section of the rear side wall of the cable chamber 106 and the lower section of the rear side wall of the busbar chamber 102 are also provided with fractures, and the wiring trolley 9 corresponds to the fractures on the same vertical line.

[0060] Specifically, in combination with Figure 2-4 The contact box 3 is installed on the front side plate of the wiring trolley 9, and the upper part of the rear side plate of the wiring trolley 9 is installed with an insulator 91 connected to the line row 93 entering the busbar chamber 102, and the lower part of the rear side plate of the wiring trolley 9 is installed with an insulator 91 connected to the line row 93 entering the cable chamber 106.

[0061] The line row 93 entering the busbar chamber 102 is connected to the busbar 2 of the busbar chamber 102 through the plug-in connector 92; the line row 93 entering the cable chamber 106 is also connected to the busbar 2 of the busbar chamber 102 through the plug-in connector 92. Specifically, the plug-in direction of the plug-in connector 92 is consistent with the plug-in direction of the circuit breaker moving contact 5 and the static contact 4. More specifically, the plug or socket of the plug-in connector 92 is fixedly connected to the wiring trolley 9, and the socket or plug of the plug-in connector 92 is fixedly connected to the busbar chamber 102 or the cable chamber 106.

[0062] In this way, when inspecting the insulator 91, the wiring trolley 9 can be pulled out and then inspected. Compared with the prior art of inspecting the insulator 91 inside the cabinet 1, the inspection space is larger and the obstruction of the wire row 93 can be avoided, thereby realizing the function of convenient inspection of the insulator 91.

[0063] To ensure the accuracy of the orientation during plugging, a track 6 for the wiring trolley 9 to move is also provided at the bottom of the inner cavity of the wiring chamber 104. Preferably, the track 6 is the same track 6 as the track 6 of the circuit breaker chamber 103, that is, the track 6 passes through the vertical partition 12 of the middle chamber and is laid in the circuit breaker chamber 103 and the wiring chamber 104.

[0064] In order to realize the "quick plug and pull" action of the plug-in connector 92 and the static contact 4 and the moving contact 5 of the circuit breaker, another set of power-assisting structures 8 is also provided at the position of the front wheel of the wiring trolley 9 corresponding to the track 6. The matching relationship between the front wheel of the wiring trolley 9 and the resistance structure and the matching relationship between the front wheel of the circuit breaker trolley 7 and the corresponding power-assisting structure 8 adopt the same form, which will not be repeated here.

[0065] In this embodiment, the circuit breaker trolley 7 and the wiring trolley 9 both have a locking structure in the prior art (not shown in the figure), so that when the circuit breaker trolley 7 is pushed or pulled, the wiring trolley 9 remains in a fixed position; when the wiring trolley 9 is pushed or pulled, the circuit breaker trolley 7 remains in a fixed position. The locking structure will not be described in detail here.

[0066] As required, the effective plug-in fitting length of the plug-in connector 92 is the same as the effective plug-in fitting length L of the stationary contact 4 and the moving contact 5 of the circuit breaker.

[0067] It should be noted that the plug-in connector 92 , the static contact 4 , and the circuit breaker moving contact 5 all adopt the structure of the prior art, and the only difference is the effective plug-in length, and the specific structure will not be repeated here.

[0068] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and it is intended that all changes that fall within the meaning and scope of equivalent elements are included in the present invention.

Claims

1. A compact central ring main unit, comprising a cabinet body (1), characterized in that: The inner cavity of the cabinet (1) is provided with two horizontal partitions (11) at the top and bottom, so that the inner cavity of the cabinet (1) is divided into an upper chamber, a middle chamber and a lower chamber from top to bottom; the chambers on the same layer are provided with vertical partitions (12), so that the upper chamber is divided into a metering chamber (101) and a busbar chamber (102) from front to back, the middle chamber is divided into a circuit breaker chamber (103) and a connection chamber (104) from front to back, and the lower chamber is divided into an auxiliary equipment chamber (105) and a cable chamber (106) from front to back; The wiring chamber (104) and the circuit breaker chamber (103) are both provided with rails (6) at the bottom, and the wiring chamber (104) is also provided with a wiring trolley (9) that can move on the rails (6) to facilitate the operation of pulling the wiring trolley (9) out of the wiring chamber (104); A notch (61) is provided in the middle of the track (6) in the width direction, and the width of the notch (61) is smaller than the width of the wheel of the corresponding trolley close to the corresponding vertical partition (12); a power-assisting structure (8) is provided in the notch (61) region of the track (6) to facilitate the movement of the wheel of the corresponding trolley close to the corresponding vertical partition (12); The power assist structure (8) comprises: The assist rod (81) comprises a vertical portion (811), a limiting portion (812), and a connecting portion (813) connecting the lower end of the vertical portion (811) and the lower end of the limiting portion (812), wherein the connecting portion (813) is connected to the hinge seat (82) via a pin shaft (83), and the hinge seat (82) is arranged below the track (6); A tension spring (84), one end of which is arranged at the upper end of the vertical portion (811), and the other end of which is arranged at the bottom of a bracket (86), and the bracket (86) is arranged below the track (6), so as to change the pulling rotation direction of the assist rod (81) by changing the position of the pin shaft (83); A limiting member (85) is disposed below the limiting portion (812) corresponding to the notch (61) and is used to limit the rotation angle of the assisting rod (81); Wherein, the vertical portion (811) abuts against a corresponding side wall of the notch (61).

2. The compact center-mounted ring main unit according to claim 1, characterized in that: The busbars (2) in the busbar chamber (102) are arranged in the same horizontal plane, so that the height of the busbar chamber (102) is consistent with the height of the metering chamber (101).

3. The compact center-mounted ring main unit according to claim 1, characterized in that: An insulator (91) connected to a line row (93) entering a busbar chamber (102) is installed on the upper portion of the rear side plate of the wiring trolley (9), and an insulator (91) connected to a line row (93) entering a cable chamber (106) is installed on the lower portion.

4. The compact center-mounted ring main unit according to claim 1, characterized in that: The front side plate of the wiring trolley (9) is provided with a contact box (3) having a static contact (4), and the opening of the contact box (3) faces the circuit breaker chamber (103) to facilitate plugging and mating of the circuit breaker moving contact (5) and the static contact (4).

5. The compact center-mounted ring main unit according to claim 1, characterized in that: The busbar (93) of the wiring trolley (9) is connected to the corresponding busbar (2) via a plug-in connector (92); wherein a portion of the plug-in connector (92) is correspondingly mounted on the wiring trolley (9) and another portion is mounted on the cabinet.

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