Ring main unit

Abstract

The present disclosure discloses a ring main unit (RMU) comprising a gas box, a fixing frame fixed to the inner side wall of the gas box, and a circuit breaker switch located within the gas box. The circuit breaker switch includes a circuit breaker body. The circuit breaker body includes an insulating housing and a first end and a second end located at opposite ends of the insulating housing. The first end is provided with a first fixing seat, and the second end is provided with a second fixing seat. The first and second fixing seats are both metal members and each encloses a shielding space to cover the conductive members provided on the first and second ends. The first fixing seat is fixed to the fixing frame via an insulator, and the second fixing seat is fixed to the fixing frame via another insulator.

Description

Technical Field

[0001] The present disclosure relates to the field of power equipment, and in particular to a ring main unit. Background Art

[0002] As the country's installed wind power capacity expands, wind turbine capacity is gradually becoming larger and higher-power, with units of 2MW and above becoming the mainstream. The step-up transformer for units of 2MW and above is mostly located inside the wind turbine nacelle or tower. The outlet voltage on the wind turbine tower side is 35kV. To meet the transformer capacity protection configuration requirements, switchgear, namely a 40.5kV ring main unit (RMU), must be installed inside the wind turbine tower. Limited by the size of the wind turbine tower door and the confined space inside the wind turbine tower, the demand for miniaturized RMUs is increasing. However, to meet insulation performance requirements, traditional RMUs generally do not reduce their size, resulting in an inability to meet the miniaturization requirements of wind farms. Summary of the Invention

[0003] In order to solve the problem in the related art that the volume reduction of a ring main unit is limited in order to meet the insulation performance requirements, the present disclosure provides a ring main unit with a reducible volume.

[0004] The present disclosure provides a ring main unit, comprising:

[0005] a gas box filled with insulating gas;

[0006] a fixed frame, fixed on the inner wall of the air box;

[0007] A circuit breaker switch comprising:

[0008] The circuit breaker body includes an insulating housing and a first end and a second end located at both ends of the insulating housing. A first fixing seat is provided on the first end, and a second fixing seat is provided on the second end. The first fixing seat and the second fixing seat are both metal parts and each encloses a shielding space to cover the conductive parts provided on the first end and the second end. The first fixing seat is fixed to the fixing frame via an insulator, and the second fixing seat is fixed to the fixing frame via another insulator.

[0009] Optionally, the circuit breaker switch further includes:

[0010] a transmission crank arm connected to a movable end provided on the first end, wherein a portion of the transmission crank arm and the movable end is located in a shielded space surrounded by the first fixed seat, and shielding plates for uniform electric field are provided on both sides of another portion of the transmission crank arm;

[0011] An insulating pull rod connected to the transmission crank arm;

[0012] an output crank arm, one end of which is connected to the insulating pull rod; and

[0013] an output shaft connected to the other end of the output crank arm;

[0014] The ring main unit further includes an operating mechanism, which is connected to the output shaft to drive the movable end to move.

[0015] Optionally, the first fixed seat includes a bottom wall and three side walls extending upward from the bottom wall, the bottom wall and the three side walls enclose the shielding space, the top and sides of the shielding space are formed with openings, and the transmission crank arm extends into the shielding space through the side openings.

[0016] Optionally, an incoming line bushing is provided on the gas box, and the circuit breaker body is connected to the incoming line bushing through a flexible connection, and the flexible connection extends from the opening at the top of the shielding space to the incoming line bushing, and a shielding cover with a uniform electric field is provided at the connection between the incoming line bushing and the flexible connection.

[0017] Optionally, the second fixing seat includes a connecting plate connected to the other insulator, side wings located on both sides of the connecting plate, a top plate located on the top of the connecting plate and a bottom plate located at the bottom of the connecting plate. The connecting plate, the two side wings, the top plate and the bottom plate form the shielding space, and the connecting piece between the other insulator and the connecting plate is located in the shielding space of the second fixing seat.

[0018] Optionally, the shielding space is divided into two space compartments by the bottom plate, namely an upper space compartment and a lower space compartment;

[0019] An isolating static contact is provided on the lower surface of the bottom plate, and the isolating static contact is located in the lower space compartment.

[0020] Optionally, the ring main unit further includes a three-position switch located below the circuit breaker switch and a three-position operating mechanism located in the mechanism chamber, wherein the three-position switch is fixed to the fixed frame through an insulator fixing seat, and the three-position switch includes:

[0021] a mechanism input shaft connected to the three-position operating mechanism to rotate under the drive of the three-position operating mechanism;

[0022] a crank arm plate, fixedly connected to the mechanism input shaft and capable of rotating with the mechanism input shaft, the crank arm plate having a first end and a second end;

[0023] A grounding contact fixed to the first end of the crank arm plate;

[0024] an insulating connecting plate, one end of which is connected to the second end of the crank arm plate;

[0025] a movable contact, which is movably connected to the other end of the insulating connecting plate, a first end of the movable contact being movably connected to the insulator fixing seat, a second end of the movable contact being a free end capable of being electrically connected to the grounding contact and the isolating static contact, and a connection point between the movable contact and the insulating connecting plate being located between the first end and the second end of the movable contact;

[0026] When the three-position switch is grounded and opened, when the mechanism input shaft rotates in a first direction, the first end of the crank arm plate drives the grounding contact to rotate in the first direction, and the second end of the crank arm plate drives the moving contact to rotate in a second direction opposite to the first direction through the insulating connecting plate, so that the grounding contact and the moving contact move in the opening direction at the same time;

[0027] When the three-position switch is grounded and closed, the first end of the crank arm plate drives the grounding contact to rotate in the second direction, and the second end of the crank arm plate drives the moving contact to rotate in the first direction through the insulating connecting plate. The moving contact and the grounding contact move relative to each other, so that the moving contact and the grounding contact move in the closing direction at the same time.

[0028] Optionally, moving contact shielding plates are provided on both sides of the second end of the moving contact for uniform electric field;

[0029] Shielding plates are provided on both sides of the connection between the first end of the moving contact and the insulator fixing seat for uniform electric field.

[0030] Optionally, shielding plates for uniform electric field are provided on both sides of the first end of the knee arm plate connected to the ground contact and on both sides of the second end of the knee arm plate connected to the insulating connecting plate.

[0031] Optionally, the ring main unit further comprises an outlet bushing arranged below the three-position switch, the outlet bushing is connected to the insulator fixing seat via a connecting copper rod, and a shielding cover is provided at the connection between the outlet bushing and the connecting copper rod.

[0032] Optionally, the ring network cabinet has a cabinet width of 430 mm and a cabinet depth of 850 mm.

[0033] The technical solutions provided by the embodiments of the present disclosure may have the following beneficial effects:

[0034] The present disclosure provides a ring main unit (RMU) comprising a gas box, a fixed frame fixed to the inner side wall of the gas box, and a circuit breaker switch located within the gas box. The circuit breaker switch includes a circuit breaker body. The circuit breaker body includes an insulating housing and first and second ends of the insulating housing. The first end is provided with a first fixing seat, and the second end is provided with a second fixing seat. The first and second fixing seats are both metal members and each encloses a shielding space to cover the conductive members provided on the first and second ends. The first fixing seat is fixed to the fixed frame via an insulator, and the second fixing seat is fixed to the fixed frame via another insulator. The first and second ends of the RMU are respectively provided with the first and second fixing seats, each providing a uniform electric field. Thus, compared to conventional methods that increase insulation gaps or insulating partitions to meet the insulation performance requirements of the RMU, the solution of the present disclosure can meet the insulation performance requirements of the RMU without increasing insulation gaps or insulating partitions. This also reduces the size of the RMU to a certain extent, facilitating the miniaturization of the RMU. At the same time, the circuit breaker body exposes the conductive parts arranged on the first end and the second end outside its insulating housing, and then uniformly distributes the electric field through the first fixing seat and the second fixing seat, without having to cover the conductive parts arranged on the first end and the second end within the insulating housing. In this way, compared with the overall covering, the overall volume of the circuit breaker body is also reduced, which is further conducive to the miniaturization development of the ring network cabinet, and at the same time reduces the use of insulating materials (such as epoxy resin), and can also achieve the purpose of insulation and environmental protection.

[0035] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0037] Figure 1 The figure is a front view of a ring main unit according to an exemplary embodiment.

[0038] Figure 2 The figure is a perspective view of a ring main unit according to an exemplary embodiment.

[0039] Figure 3 The figure is a front view of a ring main unit according to an exemplary embodiment.

[0040] Figure 4 The figure is a side view of a ring main unit according to an exemplary embodiment.

[0041] Figure 5 The figure is a rear view of a ring main unit according to an exemplary embodiment. DETAILED DESCRIPTION

[0042] In order to further illustrate the principle and structure of the present disclosure, preferred embodiments of the present disclosure are now described in detail with reference to the accompanying drawings.

[0043] The present disclosure provides a ring main unit (RMU) comprising a gas box, a fixed frame fixed to the inner side wall of the gas box, and a circuit breaker switch located within the gas box. The circuit breaker switch includes a circuit breaker body. The circuit breaker body includes an insulating housing and first and second ends located at opposite ends of the insulating housing. The first end is provided with a first fixing seat, and the second end is provided with a second fixing seat. The first and second fixing seats are both metal parts and each encloses a shielding space to cover the conductive members provided on the first and second ends. The first fixing seat is fixed to the fixed frame via an insulator, and the second fixing seat is fixed to the fixed frame via another insulator. The first and second ends of the RMU are respectively provided with a first and second fixing seat for uniform electric fields. In this manner, the insulation performance requirements of the RMU can be met without increasing the insulation gap and insulating partitions. This also reduces the volume of the RMU to a certain extent, facilitating the miniaturization of the RMU. At the same time, the circuit breaker body exposes the conductive parts arranged on the first end and the second end outside its insulating housing, and then uniformly distributes the electric field through the first fixing seat and the second fixing seat, without having to cover the conductive parts arranged on the first end and the second end within the insulating housing. In this way, compared with the overall covering, the overall volume of the circuit breaker body is also reduced, which is further conducive to the miniaturization development of the ring network cabinet, and at the same time reduces the use of insulating materials (such as epoxy resin), and can also achieve the purpose of insulation and environmental protection.

[0044] like Figure 1 As shown, the present disclosure provides a ring main unit 100, which can be applied to 40.5kV switchgear. The ring main unit 100 includes a housing 101, and the housing 101 has multiple functional rooms. Figures 2 to 4 As shown, the functional chamber includes a gas box 111, a low-voltage chamber 112, a mechanism chamber 113, and a cable chamber 114. Gas box 111 is filled with an insulating gas, such as sulfur hexafluoride. A circuit breaker 13 and a three-position switch 16 are housed within gas box 111. Mechanism chamber 113 houses the operating mechanism 14 for circuit breaker 13 and the three-position operating mechanism 17 for three-position switch 16.

[0045] The air box 111 is a rectangular parallelepiped as a whole, and is welded by a welding robot through programming and cooperation with a rotating tooling. The welding positioning is accurate and the welds are uniform, which improves the precision and strength of the air box 111, and also reduces the leakage rate of the air box 111, thereby ensuring the air tightness of the air box 111 to the greatest extent.

[0046] Combine Figure 5As shown, a fixed frame 12 is provided on the inner side wall of the gas box 111. The fixed frame 12 includes three spaced supports 121 provided on the left side wall of the gas box 111 and a fixed bracket 122 provided on the front side wall of the gas box 111. Each support 121 is connected to the fixed bracket 122. The two ends of the circuit breaker switch 13 are respectively fixed to two of the supports 121, and the three-position switch 16 is fixed to the other support. Figure 2 As shown, each support 121 includes a bent sheet metal 1211 welded to the left side wall of the air box 111 and a combined steel plate 1212 connected to the bent sheet metal 1211 and welded by two channel steels.

[0047] like Figure 3 As shown, the circuit breaker switch 13 includes a circuit breaker body 131 , a transmission crank arm 132 , an insulating pull rod 133 , an output crank arm 134 and an output shaft 135 .

[0048] The circuit breaker body 131 can be a vacuum circuit breaker, comprising an insulating housing and a first end and a second end located at both ends of the insulating housing. The insulating housing comprises a ceramic housing and an epoxy resin coating the ceramic housing. A first fixing seat 151 is provided on the first end, and a second fixing seat 152 is provided on the second end. Both the first fixing seat 151 and the second fixing seat 152 are metal components and each encloses a shielding space to cover the conductive components provided on the first and second ends. The first fixing seat 151 is fixed to one of the supports 121 of the fixed frame 12 via an insulator 181, and the second fixing seat 152 is fixed to the other support 121 of the fixed frame 12 via another insulator 182.

[0049] Among them, the conductive parts arranged on the first end include but are not limited to the movable end 131a, the flexible connection 131c, the transmission crank arm 132, the fasteners connecting the insulator 181 and the first fixed seat 151, the fasteners connecting the movable end 131a and the transmission crank arm 132, etc.

[0050] The conductive members provided on the second end include but are not limited to the isolating static contact 131 b , a fastener connecting the insulator 182 and the second fixing seat 152 , a fastener connecting the isolating static contact 131 b and the second fixing seat 152 , and the like.

[0051] The circuit breaker body 131 exposes the conductive parts provided on the first end and the second end outside its insulating housing, and then uniformly distributes the electric field through the first fixing seat and the second fixing seat, without having to enclose the conductive parts provided on the first end and the second end in the insulating housing. In this way, compared with the overall encapsulation (i.e., the moving end 131a, the transmission arm 132, the isolating static contact 131b, etc. are also enclosed in the insulating housing), the overall volume of the circuit breaker body is also reduced, which is further conducive to the miniaturization development of the ring network cabinet, while also reducing the use of insulating materials (such as epoxy resin), and can also achieve the purpose of insulation and environmental protection.

[0052] The movable end 131a on the first end protrudes from the insulating housing of the circuit breaker body 131 to be connected to the transmission crank arm 132. The movable end 131a is located in the shielded space of the first fixing base 151.

[0053] The first fixing base 151 includes a bottom wall and three side walls extending upward from the bottom wall. The bottom wall and the three side walls enclose a U-shaped shielding space to cover the conductive member on the first end, uniformize the electric field, and improve the electric field distribution. The shielding space is formed with openings at the top and sides.

[0054] like Figure 2 As shown, the flexible connector 131c extends upward through the opening at the top of the shielded space to the incoming cable bushing 191 and connects thereto. A shielding cover 154 is provided at this connection point to provide a uniform electric field and improve the electric field distribution at the connection. This shielding cover 154 is shaped like a cap and directly covers the connecting conductive member at the connection point, which may be, for example, a connecting bolt. The incoming cable bushing 191 is mounted on the sidewall of the air box 111 on the same side as the support 121, and is located above the support 121.

[0055] like Figure 3As shown, one end of the transmission crank arm 132 extends through an opening in the side of the first fixed base 151 into the shielded space and connects to the movable end 131a on the first end. The other end is connected to the insulating pull rod 133. A through-hole is defined in the center of the transmission crank arm 132. A pin 1321 extends through the through-hole and is secured at both ends to opposite side walls of the first fixed base 151. The transmission crank arm 132 is able to swing up and down relative to the pin 1321. Part of the transmission crank arm 132 is located within the shielded space enclosed by the first fixed base 151, while the remaining portion not enclosed by the shielded space is provided with a shielding plate. Specifically, shielding plates 153 are provided on both sides of this portion of the transmission crank arm to provide a uniform electric field. This allows the transmission crank arm to be located within the screen space enclosed by the first fixed base 151 or between the two shielding plates 153, thereby fully uniformizing the electric field on the transmission crank arm 132. Since the transmission crank arm 132 itself is designed to be relatively thin, the insulation level of the transmission crank arm 132 can be increased through the uniform electric field effect of the first fixing seat 151 and the shielding plate 153.

[0056] One end of the insulating pull rod 133 is connected to the transmission crank arm 132, and the electric field at this connection can be evenly distributed by the two shielding plates 153. The other end is movably connected to one end of the output crank arm 134. The other end of the output crank arm 134 is fixed to the output shaft 135 by welding. An angle is formed between the output crank arm 134 and the insulating pull rod 133. When the output crank arm 134 rotates with the output shaft 135, it can drive the insulating pull rod 133 to move up and down. One end of the output shaft 135 is connected to the operating mechanism 14. The operating mechanism 14 can drive the output shaft 135 to rotate. When the operating mechanism 14 drives the output shaft 135 to rotate in a first direction (for example, counterclockwise), the output shaft 135 drives the output crank arm 134 to rotate upward, and the output crank arm 134 drives the insulating pull rod 133 to move upward. In turn, the insulating pull rod 133 drives the transmission crank arm 132 to pull the movable end 131a upward. When the operating mechanism 14 drives the output shaft 135 to rotate in the second direction (e.g., clockwise), the output shaft 135 drives the output crank arm 134 to rotate downward, which in turn drives the insulating rod 133 downward. The insulating rod 133 then drives the transmission crank arm 132 to pull the movable end 131a downward, thereby achieving the opening and closing of the circuit breaker body 131.

[0057] Combine Figure 2 and Figure 3As shown, the second fixed base 152 includes a connecting plate 1521 connected to the other insulator 182, side wings 1522 located on both sides of the connecting plate 1521, a top plate 1523 located on top of the connecting plate 1521, and a bottom plate 1524 located at the bottom of the connecting plate 1521. The connecting plate 1521, the side wings 1522, the top plate 1523, and the bottom plate 1524 form a shielded space for the second fixed base 152. The connecting members (e.g., connecting bolts) between the other insulator 182 and the connecting plate 1521 are located within the shielded space. The shielded space is divided into two spatial compartments by the bottom plate 1524: an upper spatial compartment and a lower spatial compartment. An isolating static contact 131b is provided on the lower surface of the bottom plate 1524 and is located within the lower spatial compartment. Due to the arrangement of the second fixing seat 152 , the electric field of the conductive component at the lower end of the circuit breaker body 131 can be distributed on all surfaces of the second fixing seat 152 , so that the electric field can be evenly distributed, thereby improving the electric field distribution and increasing the insulation level.

[0058] The ring main unit 100 further includes a three-position switch 16 and a three-position operating mechanism 17 located below the circuit breaker switch 13. The three-position switch 16 is fixed to a support 121 at the bottom of the fixed frame 12 via an insulator fixing seat 161.

[0059] The three-position switch 16 includes a mechanism input shaft 162 , a crank plate 163 , a grounding contact 164 , an insulating connecting plate 165 and a moving contact 166 .

[0060] The mechanism input shaft 162 is connected to the three-position operating mechanism 17 located in the operating room 113. The three-position operating mechanism 17 can drive the mechanism input shaft 162 to rotate, thereby realizing the closing and opening of the three-position operating mechanism 17.

[0061] The lever arm plate 163 is welded and fixedly connected to the mechanism input shaft 162 and can rotate with the rotation of the mechanism input shaft 162. The lever arm plate 163 has a first end and a second end. The pin at the connection between the lever arm plate 163 and the insulating connecting plate 165 is approximately aligned with the mechanism input shaft 162. The connection point between the first end of the lever arm plate 163 and the grounding contact 164 is offset from this straight line. Due to the action of the insulating connecting plate 165, the first and second ends of the lever arm plate 163 rotate in opposite directions when the mechanism input shaft 162 rotates. The area of ​​the first end of the lever arm plate 163 is larger than that of the second end, and the area of ​​the lever arm plate 163 gradually decreases from the first end to the second end.

[0062] The first end of the crank arm plate 163 is sleeved onto the mechanism input shaft 162, and the portion of the first end of the crank arm plate 163 protruding from the mechanism input shaft 162 is connected to the ground contact 164 via a screw or other connector. Shielding plates 155 for uniform electric field are provided on both sides of the first end where the crank arm plate 163 is connected to the ground contact 164. The two shielding plates 155 clamp the connection between the crank arm plate 163 and the ground contact 164. The shielding plate 155 can be connected to the ground contact 164 and the crank arm plate 163 via an L-shaped connecting plate. The outer periphery of the shielding plate 155 is an arc structure, and the overall shape is roughly elliptical. Thus, the special design of the structural shape of the shielding plate 155 can minimize the concentration of the electric field at the tip, so that the electric field at the connection is distributed as much as possible on the plane of the shielding plate, achieving the purpose of uniform electric field.

[0063] The ground contact 164 includes a transverse portion and a vertical portion, and the transverse portion and the vertical portion form a substantially L-shaped structure. The transverse portion is fixed to the ground bus 167. Figure 5 As shown, one end of the grounding busbar 167 is connected to the housing of the ring main unit 100 via a flexible connector 168, thereby providing reliable grounding. The grounding busbar 167 is generally strip-shaped, so that it can be connected to the three-phase grounding contacts 164. That is, when the ring main unit includes multiple grounding contacts 164, each grounding contact 164 is fixed to the grounding busbar 167 at intervals.

[0064] For example Figures 2 to 4 As shown, one end of the insulating connecting plate 165 is connected to the second end of the elbow plate 163, and shielding plates 156 are provided on both sides of the connection between the insulating connecting plate 165 and the elbow plate 163. The two shielding plates 156 sandwich the connection between the insulating connecting plate 165 and the elbow plate 163 to uniformly distribute the electric field at the connection and prevent component breakdown caused by electric field concentration.

[0065] The other end of the insulating connecting plate 165 is connected to the moving contact 164 via a pin, allowing the moving contact to rotate with the rotation of the mechanism input shaft 162. The moving contact 166 is roughly elongated, with the pin connecting the insulating connecting plate 165 and the moving contact 166 located in or near the center of the moving contact 166, more specifically, between the first and second ends of the moving contact 166. The first end of the moving contact 166 is movably connected to the insulator holder 161, while the second end is free and can be electrically connected to the ground contact 164 and the isolating stationary contact 131b. The moving contact 166 can rotate relative to the insulator holder 161 when pulled by the insulating connecting plate 165. The insulating connecting plate 165 and the crank arm 163 form an angle, and the connection point between the crank arm 163 and the insulating connecting plate 165 is located at the lower end of the insulating connecting plate 165. The insulating connecting plate 165 and the moving contact 166 form an angle, and the angle changes with the rotation of the mechanism input shaft 162 .

[0066] When the three-position switch is in the isolated trip state and the grounding trip state, and the grounding switch part needs to be closed, the mechanism input shaft 162 rotates under the drive of the three-position operating mechanism 17. When the mechanism input shaft 162 rotates in the second direction (for example, counterclockwise), the first end of the crank arm plate 163 drives the grounding contact to rotate in the second direction (for example, counterclockwise) along with the mechanism input shaft 162. The second end of the crank arm plate 163 drives the insulating connecting plate 165 to make the second end of the moving contact 166 rotate in the first direction around the first end of the moving contact 166, that is, the second end of the moving contact 166 approaches the grounding contact 164 under the pull of the insulating connecting plate 165, and after rotating a certain angle, the second end of the moving contact 166 is electrically contacted with the grounding contact 164 to achieve grounding closing. Because grounding contact 164 and movable contact 166 move relative to each other and simultaneously toward grounding, their closing speed is increased, effectively reducing arcing time, contact erosion, and extending product life. Compared to conventional methods that increase closing speed by increasing the operating work of the mechanism, such as increasing spring energy, this method increases the operating mechanism and service life of the three-position switch, improving product stability.

[0067] When the grounding switch part needs to be opened, the mechanism input shaft 162 rotates in the first direction (i.e. clockwise), driving the crank arm plate 163 to rotate, and at the same time driving the grounding contact 164 and the moving contact 166 to move in the opening direction, that is, the grounding contact 164 and the moving contact 166 move in opposite directions, the grounding contact 164 rotates clockwise with the mechanism input shaft 162, and the moving contact 166 moves counterclockwise around its first end.

[0068] When the three-position switch is in the isolation trip state and the grounding trip state, and the isolation switch part needs to be closed, when the mechanism input shaft 162 moves in the first direction (for example, clockwise), the mechanism input shaft 162 drives the crank arm plate 163 to rotate, and the first end of the crank arm plate 163 drives the grounding contact 164 to rotate in the first direction, and the second end of the crank arm plate 163 drives the moving contact 66 to rotate around its first end in the second direction opposite to the first direction (for example, counterclockwise) through the insulating connecting plate 165, that is, the second end of the moving contact 166 approaches the isolation static contact 131b under the push of the insulating connecting plate 165, and after rotating a certain angle, the second end of the moving contact 166 is electrically contacted with the isolation static contact 131b to achieve isolation closing.

[0069] When the isolating switch part needs to be opened, the mechanism input shaft 162 rotates in the second direction (i.e. counterclockwise), driving the crank arm plate 163 to rotate, and the insulating connecting plate 165 drives the moving contact 166 to move in the isolation and opening direction, and the isolating switch part returns to the open state.

[0070] Moving contact shielding plates 157 are provided on both sides of the second end of the moving contact 166 for uniform electric field. The two moving contact shielding plates 157 clamp the second end of the moving contact 166 in the middle, so that the electric field at the tip of the second end can be uniform.

[0071] Shielding plates 158 are also provided on both sides of the connection between the first end of the moving contact 166 and the insulator fixing seat 161. The shielding plate 158 is roughly circular, so that the electric field can be more evenly distributed on the shielding plate 158, and electric field concentration can be avoided as much as possible.

[0072] like Figure 2 As shown, the ring main unit 100 further includes an outlet bushing 21 disposed below the three-position switch 16. The outlet bushing 21 is connected to the insulator fixing seat 161 via a connecting copper rod 22. A shielding cover 159 is provided at the connection between the outlet bushing 21 and the connecting copper rod 22 to uniformly distribute the electric field at the connection.

[0073] The above ring main unit can be applied to the three-phase current power grid. Correspondingly, the ring main unit can be provided with corresponding circuit breaker switches and three-position switches. Figures 2 to 5 As shown, the ring main unit 100 is used for a three-phase current grid, and is correspondingly provided with three circuit breakers and three three-position switches, wherein the output shafts of the circuit breakers of each phase are the same, and the input shafts of the three-position switches are the same.

[0074] In the present disclosure, shielding plates or shielding covers are added to the circuit breaker switch and three-position switch where electric field concentration may occur to meet insulation performance requirements without increasing the isolation gap, thereby achieving the purpose of reducing the size of the ring main unit. In addition, the conductive parts on both ends of the circuit breaker switch are not enclosed in their insulating shells, and the overall size of the circuit breaker switch is also reduced accordingly, so that the cabinet depth of the ring main unit of the present disclosure can be reduced to 850mm and the cabinet width can be reduced to 430mm. Compared with traditional ring main units with a cabinet depth of more than 900mm and a cabinet width of more than 550mm, the size of the ring main unit of the present disclosure is significantly reduced.

[0075] The above are only preferred feasible embodiments of the present disclosure and are not intended to limit the protection scope of the present disclosure. Any equivalent structural changes made using the contents of the present disclosure and the drawings are included in the protection scope of the present disclosure.

Claims

1. A ring main unit, characterized in that: include: a gas box filled with insulating gas; a fixed frame, fixed on the inner wall of the air box; operating mechanism; A circuit breaker switch comprising: A circuit breaker body, comprising an insulating housing and first and second ends located at opposite ends of the insulating housing, wherein a first fixing seat is provided on the first end and a second fixing seat is provided on the second end. The first and second fixing seats are both metal members and each encloses a shielding space to cover the conductive members provided on the first and second ends. The first fixing seat is fixed to the fixing frame via an insulator, and the second fixing seat is fixed to the fixing frame via another insulator. The ring main unit further includes a three-position switch located below the circuit breaker switch and a three-position operating mechanism located in the mechanism room. The three-position switch is fixed to the fixed frame through an insulator fixing seat. The three-position switch includes: a mechanism input shaft connected to the three-position operating mechanism to rotate under the drive of the three-position operating mechanism; a crank arm plate, fixedly connected to the mechanism input shaft and capable of rotating with the mechanism input shaft, the crank arm plate having a first end and a second end; A grounding contact fixed to the first end of the crank arm plate; an insulating connecting plate, one end of which is connected to the second end of the crank arm plate; A moving contact is movably connected to the other end of the insulating connecting plate.

2. The ring main unit according to claim 1, characterized in that: The circuit breaker switch further comprises: a transmission crank arm connected to a movable end provided on the first end, wherein a portion of the transmission crank arm and the movable end is located in a shielded space surrounded by the first fixed seat, and shielding plates for uniform electric field are provided on both sides of another portion of the transmission crank arm; An insulating pull rod connected to the transmission crank arm; an output crank arm, one end of which is connected to the insulating pull rod; and an output shaft connected to the other end of the output crank arm; The operating mechanism is connected to the output shaft to drive the movable end to move.

3. The ring main unit according to claim 2, characterized in that: The first fixing seat includes a bottom wall and three side walls extending upward from the bottom wall, the bottom wall and the three side walls enclose the shielding space, the top and sides of the shielding space are formed with openings, and the transmission crank arm extends into the shielding space through the side openings.

4. The ring main unit according to claim 3, characterized in that: The gas box is provided with an inlet bushing, and the circuit breaker body is connected to the inlet bushing through a flexible connection. The flexible connection extends from the opening at the top of the shielding space to the inlet bushing, and a shielding cover with a uniform electric field is provided at the connection between the inlet bushing and the flexible connection.

5. The ring main unit according to claim 1, characterized in that: The second fixing seat includes a connecting plate connected to the other insulator, side wings located on both sides of the connecting plate, a top plate located on the top of the connecting plate and a bottom plate located at the bottom of the connecting plate. The connecting plate, the two side wings, the top plate and the bottom plate form the shielding space, and the connecting piece between the other insulator and the connecting plate is located in the shielding space of the second fixing seat.

6. The ring main unit according to claim 5, characterized in that: The shielding space is divided into two space compartments by the bottom plate, namely an upper space compartment and a lower space compartment; An isolating static contact is provided on the lower surface of the bottom plate, and the isolating static contact is located in the lower space compartment.

7. The ring main unit according to claim 6, characterized in that: The first end of the movable contact is movably connected to the insulator fixing seat, the second end of the movable contact is a free end that can be electrically connected to the grounding contact and the isolating static contact, and the connection point between the movable contact and the insulating connecting plate is located between the first end and the second end of the movable contact; When the three-position switch is grounded and opened, when the mechanism input shaft rotates in a first direction, the first end of the crank arm plate drives the grounding contact to rotate in the first direction, and the second end of the crank arm plate drives the moving contact to rotate in a second direction opposite to the first direction through the insulating connecting plate, so that the grounding contact and the moving contact move in the opening direction at the same time; When the three-position switch is grounded and closed, the first end of the crank arm plate drives the grounding contact to rotate in the second direction, and the second end of the crank arm plate drives the moving contact to rotate in the first direction through the insulating connecting plate. The moving contact and the grounding contact move relative to each other, so that the moving contact and the grounding contact move in the closing direction at the same time.

8. The ring main unit according to claim 7, characterized in that: Moving contact shielding plates are provided on both sides of the second end of the moving contact for uniform electric field; Shielding plates are provided on both sides of the connection between the first end of the moving contact and the insulator fixing seat for uniform electric field.

9. The ring main unit according to claim 7, characterized in that: Shielding plates for uniform electric field are provided on both sides of the first end of the knee arm plate connected to the ground contact and on both sides of the second end of the knee arm plate connected to the insulating connection plate.

10. The ring main unit according to claim 7, characterized in that: The ring network cabinet also includes an outlet bushing arranged below the three-position switch, the outlet bushing is connected to the insulator fixing seat through a connecting copper rod, and a shielding cover is provided at the connection between the outlet bushing and the connecting copper rod.

11. The ring main unit according to claim 1, characterized in that: The ring network cabinet has a width of 430 mm and a depth of 850 mm.

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