252kV three-position switch with last item indication function

Abstract

The invention relates to the technical field of GIS (Gas Insulated Switchgear), in particular to a 252kV three-position switch with a last item indication function. The insulation connecting rod drives moving contacts of a three-phase switch to act at the same time, and the insulation connecting rod is in transmission with the moving contacts of the corresponding switch through a part located in a shell; and the terminal indicating mechanism is arranged on one side of the shell. When an operator manually drives the insulating connecting rod, the indicating rod can be temporarily clamped into the clamping groove to prevent the rotating disc from continuously rotating through the arranged clamping groove and the arranged indicating rod, limb feedback is provided for the operator, and after the operator finds that the indicating rod can be rapidly separated from the clamping groove, so that continuous rotation of the rotating disc is not affected. Moreover, the depths of part of the clamping grooves are different, so that the lengths of the indicating rods extending into the clamping grooves are different, the position of the moving contact is known by identifying the extending lengths, and visual feedback is provided for an operator.

Description

Technical Field

[0001] This invention relates to the field of GIS (Gas Insulated Metal Enclosed Switchgear) technology, and more specifically, to a 252kV three-position switch with a last item indicator function. Background Technology

[0002] 252kV high-voltage switches generally use gas-insulated metal-enclosed switchgear, abbreviated as GIS. GIS equipment combines circuit breakers, disconnectors, grounding switches and other electrical equipment together, and has the advantages of compact structure, small footprint, high reliability, good seismic performance, low noise, and low daily maintenance workload, and is widely used in power systems.

[0003] Because the moving contacts of GIS equipment are located inside a metal casing, their position is not easily observable, making it impossible to directly assess whether the contact action is fully completed. Currently, an auxiliary switch is typically installed inside the operating mechanism box, connected to the disconnector via a transmission mechanism. The position of the moving contact is indicated by the switching of the auxiliary switch, and its status is displayed on a back-end monitor. However, since the movement from the operating mechanism box to the moving contacts of the GIS equipment involves a series of transmission links, transmission losses are inevitable. When the GIS equipment experiences internal jamming in the operating mechanism, a jam in a transmission link, or a malfunction in the auxiliary switch, the moving contacts may not have actually opened or closed after the operating mechanism has actuated, even though the auxiliary switch has already switched, and the back-end monitor shows the moving contacts as opened or closed. Therefore, the current lack of dual redundancy verification for the final position of the three-phase moving contacts may lead to safety accidents such as operation under load or maintenance without grounding. Summary of the Invention

[0004] The purpose of this invention is to provide a 252kV three-position switch with a final item indication function. By setting multiple slots on the rotating disk and using an indicator rod to temporarily enter the slots, it provides physical and visual feedback to the operator, thereby solving the problem mentioned in the background art, namely, the lack of dual redundancy verification of the final position of the moving contact.

[0005] To achieve the above objectives, a 252kV three-position switch with a last-phase indicator function includes an insulating link that simultaneously drives the moving contacts of the three-phase switches. The insulating link is driven by the moving contacts of the corresponding switches through a portion located inside the housing. It also includes a last-phase indicator mechanism disposed on one side of the housing. The last-phase indicator mechanism includes an outer cover, a rotating disk, and an indicator rod. The outer cover is fixed to the part of the housing corresponding to the end of the insulating connecting rod; The rotating disk is located inside the outer cover and is fixedly connected to the insulating connecting rod on the same axis. The outer ring of the rotating disk is provided with multiple slots of different depths, which correspond to the grounding switch closed position, the isolating switch closed position and the open position, respectively. The indicator rod is slidably disposed inside the outer cover, and an elastic element for driving the indicator rod is provided at the bottom. Under the elastic action of the elastic element, the indicator rod disengages from the elastic element and temporarily enters the slot, thereby temporarily restricting the rotation of the rotating disk. Some slots are equipped with magnetic components that attract the indicator rod. Under the action of the magnetic components, the indicator rod extends into different slots to different lengths. The position of the moving contact can be obtained by observing the extension length of the indicator rod.

[0006] In the above technical solution, the temporary insertion of the indicator rod into the slot temporarily restricts the rotation of the rotating disk. Since the rotating disk is connected to an insulating rod, the insulating rod is also restricted, providing feedback to the operator. Secondly, because the depths of the multiple slots differ, the insertion length of the indicator rod varies. By observing the insertion length, the position of the moving contact can be determined, providing visual feedback to the operator.

[0007] Based on this, a protruding tube is provided at the bottom of the outer ring of the outer cover, and a movable chamber for the sliding of the indicator rod is formed inside the protruding tube. The elastic element is a compression spring located at the bottom of the movable chamber. The top of the compression spring contacts the bottom of the indicator rod. With the support of the compression spring, the top of the indicator rod is higher than the bottom of the rotating disk. At this time, the compression spring can be compressed to provide power for driving the indicator rod.

[0008] Based on this, the slot includes a trip slot, a grounding slot, and an isolation slot; wherein, the trip slot corresponds to the tripped position of the moving contact, the grounding slot corresponds to the closed position of the grounding switch of the moving contact, and the isolation slot corresponds to the closed position of the isolating switch of the moving contact.

[0009] First, let's look at the structure of the trip slot. The open ends on both sides of the trip slot expand outward to form inclined sides, and the height of the connection between the inclined sides and the side wall of the trip slot is higher than the top height of the indicator rod when it is supported by the compression spring.

[0010] Secondly, the structure of the grounding trench and the isolation trench. One wall of each of the grounding trench and the isolation trench is parallel to the indicator rod, while the other wall always forms an angle with the indicator rod. Furthermore, the grounding trench and the isolation trench are symmetrically arranged; the depths of the grounding trench and the isolation trench are different.

[0011] Based on this, the magnetic attraction assembly includes a first magnet and a second magnet that are magnetically attracted to each other. The first magnet is fixedly installed at the top of the indicator rod, and the second magnet is fixedly installed at the inner end of the grounding groove and the isolation groove.

[0012] In another technical solution, the outer ring of the indicator rod is provided with multiple indicator areas whose positions and numbers correspond to the card slots, and the multiple indicator areas are different colors; A cover is fixedly installed at the end of the rotating disk away from the insulating connecting rod. The diameter of the cover is the same as the diameter of the rotating disk. An observation area is formed between the inner ring of the cover and the inner ring of the outer cover. The position status of the moving contact is obtained by observing the color of the corresponding part of the observation area by the indicator rod. In this technical solution, the color of each indicator area corresponds to a position. For example, area a is green, corresponding to the open position; area b is red, corresponding to the closed position of the isolating switch; and area c is yellow, corresponding to the closed position of the grounding switch. At this time, the position of the moving contact can be known by observing the color of the corresponding observation area of ​​the indicator rod.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this 252kV three-position switch with end-item indicator function, when the operator manually drives the insulating linkage, the indicator rod can be temporarily engaged in the slot to stop the rotating disk from continuing to rotate, providing physical feedback to the operator. Once the operator notices this, the indicator rod can quickly disengage from the slot, thus not affecting the continued rotation of the rotating disk. Furthermore, the different depths between some slots result in different lengths of the indicator rod extending into the slot. By identifying the extension length, the operator can understand the position of the moving contact, providing visual feedback to the operator.

[0014] 2. In this 252kV three-position switch with last item indication function, by setting different colors on the indicator rod, the indicator rod can not only block the rotation of the rotating disk to improve the physical feedback for the operator, but also allow the operator to quickly understand the position of the moving contact by observing the color displayed by the indicator rod in the observation area, thus realizing dual redundancy verification of the final position of the moving contact. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the last indicator mechanism of the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the structure of the last indicator mechanism of the present invention. Figure 2 ; Figure 4 This is a schematic diagram of the structure of the indicator rod of the present invention; Figure 5 This is a schematic diagram of the rotating disk of the present invention; Figure 6 This is a schematic diagram of the working state of the rotating disk of the present invention. Figure 1 ; Figure 7This is a schematic diagram showing the position of the indicator rod of the present invention; Figure 8 This is a schematic diagram of the structure of the shielding cover of the present invention; Figure 9 This is a schematic diagram of the working state of the rotating disk of the present invention. Figure 2 .

[0016] The meanings of the labels in the diagram are as follows: 100. Housing; 101. Insulating connecting rod; 102. Drive mechanism; 110. Last item indicator mechanism; 111. Outer cover; 112. Transparent cover; 113. Shielding cover; 114. Observation area; 120. Indicator rod; 121. Activity chamber; 122. Compression spring; 123. Indicator area; 124. First magnet; 130. Rotating disk; 131. Circuit breaker slot; 132. Inclined side; 133. Grounding slot; 134. First slot wall; 135. Second slot wall; 136. Isolation slot; 137. Third slot wall; 138. Fourth slot wall; 139. Second magnet. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] To address the current lack of dual-redundancy verification for the final position of the moving contact, this invention provides a 252kV three-position switch with a last-term indication function, such as... Figure 1As shown, the three-position switch includes an insulating link 101 that simultaneously drives the moving contacts of the three-phase switches. The insulating link 101 is driven by the moving contacts of the corresponding switches through a portion located inside the housing 100. The moving contacts reciprocate linearly. The stationary contacts of the isolating switch and the grounding switch inside the housing 100 are located at opposite ends of the moving contacts, meaning the moving contacts are in the middle position. This design structurally achieves logical interlocking between the isolating switch and the grounding switch. When the isolating switch is in the closed position, the grounding switch must be in the open position; similarly, when the grounding switch is in the closed position, the isolating switch must be in the open position. To achieve the switching of the moving contacts from the closed position of the isolating switch to the closed position of the grounding switch, the moving contacts must first move from the closed position of the isolating switch to the open position, and then move to the closed position of the grounding switch.

[0021] The insulating connecting rod 101 is driven by a drive mechanism 102 located on one side of the housing 100. The drive mechanism 102 can be electric, manual, or a combination of electric and manual operation.

[0022] The three-position switch also includes a last-item indicator 110 disposed on one side of the housing 100. For example... Figure 2 As shown, the final indicator mechanism 110 comprises three parts: an outer cover 111, an indicator rod 120, and a rotating disk 130. Among them, combined with... Figure 3 The outer cover 111 has an opening at one end facing the housing 100 for the insulating connecting rod 101 to pass through. The opening end of the outer cover 111 is bent outward and fixed to the housing 100 at the corresponding end of the insulating connecting rod 101. The rotating disk 130 is located inside the outer cover 111 and is coaxially fixed to the insulating connecting rod 101 by bolts, welding, or snap-fitting, so that the rotating disk 130 can rotate synchronously with the insulating connecting rod 101. The outer ring of the rotating disk 130 is provided with multiple slots of different depths, which correspond to the grounding switch closed position, the isolating switch closed position, and the open position, respectively. The indicator rod 120 is slidably disposed within the outer cover 111, and an elastic element for driving the indicator rod 120 is provided at its bottom. Under the elastic action of the elastic element, the indicator rod 120 disengages from the elastic element and temporarily enters the slot, temporarily restricting the rotation of the rotating disk 130. Furthermore, some slots are provided with magnetic attraction components that magnetically attract the indicator rod 120. Under the action of the magnetic attraction components, the length of the indicator rod 120 extending into different slots varies. By observing the extension length of the indicator rod 120, the current position of the moving contact can be obtained. Correspondingly, as... Figure 3 As shown, the end of the outer cover 111 is made of transparent material. In practice, the end of the outer cover 111 is set as an open structure, and then the transparent cover 112 is connected to the open end of the outer cover 111 to achieve transparency at the end of the outer cover 111.

[0023] In other words, when the operator manually drives the insulating connecting rod 101, the indicator rod 120 can be temporarily engaged in the slot to prevent the rotating disk 130 from continuing to rotate, providing physical feedback to the operator. Once the operator notices this, the indicator rod 120 can quickly disengage from the slot, thus not affecting the continued rotation of the rotating disk 130. Furthermore, the different depths of some slots result in varying lengths of the indicator rod 120 extending into the slots. By identifying the extension length, the operator can determine the position of the moving contact, providing visual feedback to the operator.

[0024] Specifically, the indicator rod 120 can be cylindrical, square, or other shapes. This embodiment uses a cylindrical shape as an example to disclose the placement of the indicator rod 120. Figure 4 As shown, a protruding tube is provided at the bottom of the outer ring of the outer cover 111, and an active chamber 121 is formed inside the protruding tube for the sliding of the indicator rod 120. This design keeps the indicator rod 120 in a vertical state and located in the lower middle part of the outer cover 111. In this way, the elastic member will bounce the indicator rod 120 upward and put it into the slot. When the kinetic energy of the indicator rod 120 is lost, the indicator rod 120 will return to its original position by its own gravity.

[0025] Specifically, the elastic element is a compression spring 122 located at the bottom of the active chamber 121. The top of the compression spring 122 contacts the bottom of the indicator rod 120, but the two are not connected. Next, as... Figure 7 As shown, under the elastic support of the compression spring 122, the top height of the indicator rod 120 is higher than the bottom height of the rotating disk 130. With this design, when the top of the indicator rod 120 abuts against the outer ring of the rotating disk 130, the compression spring 122 is in a compressed state. Therefore, when the slot rotates to the front of the indicator rod 120, the compression spring 122 deforms and resets, springing the indicator rod 120 into the slot. The method by which the indicator rod 120 disengages from the slot will be described in detail along with the slot itself.

[0026] Figure 5 The specific structure of the slots is shown. As shown in the figure, the slots are formed by the inward indentation of the outer ring of the rotating disk 130. There are three slots, corresponding to the closed position of the grounding switch, the closed position of the isolating switch, and the open position, respectively. Specifically, they are the open slot 131, the grounding slot 133, and the isolating slot 136. When the open slot 131 rotates to the indicator rod 120, the moving contact is in the open position; when the grounding slot 133 rotates to the indicator rod 120, the moving contact is in the closed position of the grounding switch; when the isolating slot 136 rotates to the indicator rod 120, the moving contact is in the closed position of the isolating switch. In the above, since the open slot 131 is in the middle, it needs to pass the indicator rod 120 during both the forward and reverse rotation of the rotating disk 130. Therefore, the structure of the open slot 131 is different from that of the grounding slot 133 and the isolating slot 136, which will be described separately below: The openings on both sides of the trip slot 131 expand outward to form inclined sides 132, which are then combined with... Figure 7 As shown, the height A at the connection between the inclined side 132 and the side wall of the trip slot 131 is higher than the top height of the indicator rod 120 when it is supported by the compression spring 122. Thus, the position of the indicator rod 120 after it resets due to its own gravity is... Figure 7 When the indicator rod 120 is in the same position, as the rotating disk 130 rotates, since the inclined side 132 is always inclined to the side wall of the active chamber 121, the indicator rod 120 is driven downward through the inclined side 132, so that the top of the indicator rod 120 abuts against the outer ring of the rotating disk 130 again, thus realizing the operation of the indicator rod 120 disengaging from the trip slot 131.

[0027] The grounding groove 133 has a first groove wall 134 and a second groove wall 135 on its two sides. When the indicator rod 120 enters the grounding groove 133, the first groove wall 134 is parallel to the indicator rod 120. This parallelism prevents the first groove wall 134 from exerting a force on the indicator rod 120 to move it toward the compression spring 122, thus allowing the indicator rod 120 to restrict the rotation of the rotating disk 130 through the first groove wall 134. The second groove wall 135 always forms an angle with the indicator rod 120, that is, the second groove wall 135 is always inclined toward the indicator rod 120. When the second groove wall 135 moves toward the indicator rod 120, the second groove wall 135 guides the indicator rod 120 to leave the grounding groove 133.

[0028] The isolation groove 136 has a third groove wall 137 and a fourth groove wall 138 on its two sides. When the indicator rod 120 enters the isolation groove 136, the third groove wall 137 is parallel to the indicator rod 120. This parallelism prevents the third groove wall 137 from exerting a force on the indicator rod 120 to move towards the compression spring 122, thus allowing the indicator rod 120 to restrict the rotation of the rotating disk 130 through the third groove wall 137. The fourth groove wall 138 always forms an angle with the indicator rod 120, that is, the fourth groove wall 138 is always inclined to the indicator rod 120. When the fourth groove wall 138 moves towards the indicator rod 120, the fourth groove wall 138 guides the indicator rod 120 to disengage from the grounding groove 133.

[0029] Therefore, the grounding groove 133 and the isolation groove 136 have basically the same structure. The main difference lies in that, on the one hand, the grounding groove 133 and the isolation groove 136 are symmetrically arranged, and on the other hand, the depths of the grounding groove 133 and the isolation groove 136 are different. For example, the depth H1 of the grounding groove 133 is greater than the depth H2 of the isolation groove 136, or the depth of the isolation groove 136 is greater than the depth of the grounding groove 133.

[0030] Combination Figure 4 and Figure 5The magnetic attraction assembly includes a first magnet 124 and a second magnet 139. The first magnet 124 is fixedly disposed at the top of the indicator rod 120, and the second magnet 139 is fixedly disposed at the inner end of the grounding groove 133 and the isolation groove 136. Thus, when the indicator rod 120 enters the grounding groove 133 or the isolation groove 136, the second magnet 139 can attract the indicator rod 120 to the inner end of the grounding groove 133 or the isolation groove 136 through the first magnet 124. Since the top of the indicator rod 120 is located at the inner end of the rotating disk 130 or the isolation groove 136, and the rotating disk 130 and the isolation groove 136 have different depths, the length to which the indicator rod 120 extends is also different. Furthermore, the inner ends of the grounding groove 133 and the isolation groove 136 are both arc-shaped structures, which ensure stable contact between the rotating disk 130 and the indicator rod 120 during rotation.

[0031] Although the position of the moving contact can be observed by the length of the insertion, a more intuitive and faster method is needed to determine its location. Figure 4 As shown, the present invention also provides three indicator areas 123 of different colors on the outer ring of the indicator rod 120, and the distribution positions of the three indicator areas 123 are as follows: Figure 7 The indicator is divided into three zones: zone a, zone b, and zone c. Each zone has a different color, and each color corresponds to a specific position. For example, zone a is green, corresponding to the open position; zone b is red, corresponding to the closed position of the isolating switch; and zone c is yellow, corresponding to the closed position of the grounding switch.

[0032] And, as Figure 3 and Figure 8 As shown, a shielding cover 113 is fixedly installed at the end of the rotating disk 130 away from the insulating connecting rod 101. The diameter of the shielding cover 113 is the same as the diameter of the rotating disk 130, and it is used to shield the trip slot 131, the grounding slot 133, and the isolation slot 136. The area not shielded by the grounding slot 133 forms the observation area 114, which is the area between the inner ring of the shielding cover 113 and the inner ring of the outer cover 111. At this time, the position of the moving contact can be known by observing the color of the indicator rod 120 corresponding to the observation area 114.

[0033] The working principle of this invention will be described in detail below: like Figure 6As shown, when the moving contact needs to be moved to the open position, the operator rotates the insulating linkage 101, which drives the rotating disk 130 to rotate in the direction of the arrow. When the indicator rod 120 abuts against the outer ring of the rotating disk 130, the compression spring 122 is compressed and stores energy. When the opening slot 131 rotates to the front of the indicator rod 120, the compression spring 122 will quickly rebound and push the indicator rod 120 to move. Under the action of inertia, the indicator rod 120 disengages from the compression spring 122 and enters the opening slot 131. If the rotating disk 130 continues to rotate at this time, the indicator rod 120 will be stuck in the opening slot 131, preventing the rotation of the rotating disk 130, which is equivalent to providing physical feedback to the operator. (Continue to refer to...) Figure 7 When the rotating disk 130 stops rotating, the compression spring 122 falls back to its original position under its own weight, and then... (refer to...) Figure 8 Area a is located in observation area 114. When the operator sees area a, it means that the moving contact is in the open position.

[0034] like Figure 9 As shown, when the moving contact needs to be moved to the closed position of the disconnecting switch, the operator rotates the insulating connecting rod 101. The insulating connecting rod 101 drives the isolation groove 136 to rotate in the direction of the arrow. When the isolation groove 136 rotates to the front of the indicator rod 120, the compression spring 122 pushes the indicator rod 120 into the isolation groove 136. At the same time, the second magnet 139 attracts the top of the indicator rod 120. When the rotating disk 130 continues to rotate, the indicator rod 120 inside the second magnet 139 will stop the rotation of the rotating disk 130 through the third groove wall 137, providing physical feedback to the operator. At this time, area a is in the observation area 114. When the operator sees the color of area b, it indicates that the moving contact is in the closed position of the disconnecting switch. When it is necessary to open the switch, refer to... Figure 9 In the right half of the rotating disk 130, the rotating disk 130 pushes the indicator rod 120 downward through the fourth groove wall 138, so that the top of the indicator rod 120 abuts against the outer ring of the rotating disk 130.

[0035] The principle of the moving contact moving to the closed position of the grounding switch is the same as that of the moving contact moving to the closed position of the disconnecting switch, and will not be elaborated here.

[0036] In summary, by setting different colors on the indicator rod 120, the indicator rod 120 can not only block the rotation of the rotating disk 130 to improve the operator's physical feedback, but also allow the operator to quickly understand the position of the moving contact by observing the color displayed by the indicator rod 120 in the observation area 114, thus achieving dual redundancy verification of the final position of the moving contact.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A 252kV three-position switch with a last-phase indicator function, comprising an insulating connecting rod (101) that simultaneously drives the moving contacts of the three-phase switches, wherein the insulating connecting rod (101) is driven by a portion located within a housing (100) and the moving contacts of the corresponding switches; characterized in that: It also includes a last item indicator mechanism (110) disposed on one side of the housing (100), the last item indicator mechanism (110) including an outer cover (111), a rotating disk (130) and an indicator rod (120). The outer cover (111) is fixed to the part of the housing (100) corresponding to the end of the insulating connecting rod (101); The rotating disk (130) is located inside the outer cover (111) and is coaxially fixedly connected to the insulating connecting rod (101); the outer ring of the rotating disk (130) is provided with multiple slots of different depths, and the multiple slots correspond to the grounding switch closed position, the isolating switch closed position and the open position respectively; The indicator rod (120) is slidably disposed inside the outer cover (111), and an elastic element for driving the indicator rod (120) is provided at the bottom. Under the elastic action of the elastic element, the indicator rod (120) disengages from the elastic element and temporarily enters the slot, thereby temporarily restricting the rotation of the rotating disk (130). Some slots are equipped with magnetic components that are magnetically attracted to the indicator rod (120). Under the action of the magnetic components, the length of the indicator rod (120) extending into different slots is different. The position of the moving contact can be obtained by observing the length of the indicator rod (120) extending into different slots.

2. The 252kV three-position switch with last item indication function according to claim 1, characterized in that: The indicator rod (120) is in a vertical state and is located in the lower middle part of the outer cover (111). When the kinetic energy of the indicator rod (120) disappears, the indicator rod (120) resets by its own gravity.

3. The 252kV three-position switch with last item indication function according to claim 2, characterized in that: The bottom of the outer ring of the outer cover (111) is provided with a convex tube, and the inside of the convex tube forms an active chamber (121) for the sliding of the indicator rod (120).

4. The 252kV three-position switch with last item indication function according to claim 3, characterized in that: The elastic element is a compression spring (122) set at the bottom of the active chamber (121). The top of the compression spring (122) contacts the bottom of the indicator rod (120). Under the support of the compression spring (122), the top height of the indicator rod (120) is higher than the bottom height of the rotating disk (130).

5. The 252kV three-position switch with last item indication function according to claim 1, characterized in that: The card slot includes a circuit breaker slot (131), a grounding slot (133), and an isolation slot (136); Among them, the trip slot (131) corresponds to the trip position of the moving contact, the grounding slot (133) corresponds to the grounding switch closing position of the moving contact, and the isolation slot (136) corresponds to the isolation switch closing position of the moving contact.

6. The 252kV three-position switch with last item indication function according to claim 5, characterized in that: The opening ends on both sides of the gate slot (131) expand outward to form a sloping side (132). The height of the connection between the sloping side (132) and the side wall of the gate slot (131) is higher than the top height of the indicator rod (120) when it is supported by the compression spring (122).

7. The 252kV three-position switch with last item indication function according to claim 5, characterized in that: One wall of the grounding groove (133) and the isolation groove (136) is parallel to the indicator rod (120), and the other wall always forms an angle with the indicator rod (120).

8. The 252kV three-position switch with last item indication function according to claim 7, characterized in that: The grounding groove (133) and the isolation groove (136) are symmetrically arranged; the grounding groove (133) and the isolation groove (136) have different depths.

9. The 252kV three-position switch with last item indication function according to claim 5, characterized in that: The magnetic attraction assembly includes a first magnet (124) and a second magnet (139) that are magnetically attracted to each other. The first magnet (124) is fixedly disposed at the top of the indicator rod (120), and the second magnet (139) is fixedly disposed at the inner end of the grounding groove (133) and the isolation groove (136).

10. The 252kV three-position switch with last item indication function according to claim 1, characterized in that: The outer ring of the indicator rod (120) is provided with multiple indicator areas (123) whose positions and numbers correspond to the card slots, and the colors of the multiple indicator areas (123) are different; A shielding cover (113) is fixedly installed at the end of the rotating disk (130) away from the insulating connecting rod (101). The diameter of the shielding cover (113) is the same as the diameter of the rotating disk (130). An observation area (114) is formed between the inner ring of the shielding cover (113) and the inner ring of the outer cover (111). The position status of the moving contact is obtained by observing the color of the part of the observation area (114) corresponding to the observation indicator rod (120).

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