252kv three-position switch with last item indicating function

Abstract

This invention relates to the field of GIS (Gas Insulated Metal Enclosed Switchgear) technology, specifically to a 252kV three-position switch with a last-phase indicator function. It 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 via a portion located within the housing. It also includes a last-phase indicator mechanism disposed on one side of the housing. When the operator manually drives the insulating link, the indicator rod can temporarily engage in the slot to prevent 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 slots. By identifying the extension length, the operator can determine the position of the moving contact, providing visual feedback to the operator.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of GIS (gas insulated metal-enclosed switch), in particular to a 252kV three-position switch with a last item indicating function. BACKGROUND

[0002] The high-voltage switch of 252kV generally adopts gas insulated metal-enclosed switch device, referred to as GIS. The GIS device combines circuit breakers, disconnectors, grounding switches and other electrical devices together, has the advantages of compact structure, small space occupation, high reliability, good anti-seismic performance, low noise, small daily maintenance workload and the like, and is widely used in power systems.

[0003] Since the moving contact of the GIS device is in the metal shell, the directivity is not strong, and the contact condition cannot be directly observed, so it is impossible to judge whether the contact opening and closing action is completely in place. At present, an auxiliary switch is usually installed in the operating mechanism box, the knife switch and the auxiliary switch are connected through a transmission mechanism, the position of the moving contact is represented through the switching of the auxiliary switch, and the state of the auxiliary switch is displayed on the display in the background. However, since the moving contact of the GIS device needs to pass through a series of transmission links from the operating mechanism box, transmission loss will inevitably occur in the transmission process. When the operating mechanism is internally stuck, the transmission of some links is stuck, or the auxiliary switch fails, etc., the moving contact of the GIS device may not be really opened or closed to place after the operating mechanism is operated, while the auxiliary switch has completed the switching, and the display on the background display shows that the moving contact has been opened or closed to place. As can be seen, the current lacks double redundant verification of the final position of the three-phase moving contact, which may cause safety accidents such as load operation or ungrounded maintenance. SUMMARY

[0004] The purpose of the present application is to provide a 252kV three-position switch with a last item indicating function, which provides limb and visual feedback for the operator by temporarily entering the card slot with the indicating rod on the rotating disc, thereby solving the problem of lacking double redundant verification of the final position of the moving contact as proposed in the background technology.

[0005] To achieve the above purpose, the 252kV three-position switch with a last item indicating function comprises an insulation connecting rod for simultaneously driving the moving contact of the three-phase switch to act, the insulation connecting rod is in transmission with the moving contact of the corresponding switch through the part located in the shell; and a last item indicating mechanism arranged on one side of the shell, the last item indicating mechanism comprises an outer cover, a rotating disc and an indicating rod.

[0006] The outer cover is fixed at the part of the corresponding end of the insulation connecting rod of the shell;

[0007] The rotating disc is coaxially fixedly connected with the insulating connecting rod in the outer cover; a plurality of clamping grooves with different depths are arranged on the outer ring of the rotating disc, and the plurality of clamping grooves correspond to the grounding switch closing position, the isolating switch closing position and the opening position respectively.

[0008] The indicating rod is slidingly arranged in the outer cover and is provided at the bottom with an elastic member for driving the indicating rod; under the elastic action of the elastic member, the indicating rod is separated from the elastic member and temporarily enters the clamping groove, thereby temporarily limiting the rotation of the rotating disc.

[0009] Some of the clamping grooves are provided with a magnetic attraction assembly which is magnetically attracted to the indicating rod; under the action of the magnetic attraction assembly, the indicating rod extends into the different clamping grooves to different lengths, and the position of the movable contact is obtained by observing the extension length of the indicating rod.

[0010] In the above technical solution, the temporary entry of the indicating rod into the clamping groove temporarily limits the rotation of the rotating disc, and the rotating disc is connected with the insulating connecting rod, so that the insulating connecting rod is also limited, thereby providing feedback for the operator. Secondly, since the depths of the plurality of clamping grooves are different, the extension lengths of the indicating rod are different, and the position of the movable contact is obtained by observing the extension length, thereby providing visual feedback for the operator.

[0011] On this basis, the bottom of the outer ring of the outer cover is provided with a convex pipe, and an active chamber for sliding of the indicating rod is formed in the convex pipe. The elastic member is a compression spring arranged at the bottom of the active chamber, and the top of the compression spring is in contact with the bottom of the indicating rod. Under the support of the compression spring, the top end of the indicating rod is higher than the bottom height of the rotating disc, and at this time the compression spring can be compressed to provide power for driving the indicating rod.

[0012] On this basis, the clamping grooves include an opening groove, a grounding groove and an isolating groove; the opening groove corresponds to the opening position of the movable contact, the grounding groove corresponds to the grounding switch closing position of the movable contact, and the isolating groove corresponds to the isolating switch closing position of the movable contact.

[0013] Firstly, the structure of the opening groove. The opening ends of the two sides of the opening groove are outwardly expanded to form bevels, and the height of the connection between the bevels and the side walls of the opening groove is higher than the top height of the indicating rod supported by the compression spring.

[0014] Secondly, the structures of the grounding groove and the isolating groove. One of the groove walls of the grounding groove and the isolating groove is parallel to the indicating rod, and the other groove wall always forms an angle with the indicating rod. Furthermore, the grounding groove and the isolating groove are symmetrically arranged; the depths of the grounding groove and the isolating groove are different.

[0015] On this basis, the magnetic attraction assembly includes a first magnet and a second magnet which are magnetically attracted to each other; the first magnet is fixedly arranged at the top end of the indicating rod, and the second magnet is fixedly arranged at the inner end of the grounding groove and the isolating groove.

[0016] In another technical solution, the outer ring of the indicating rod is provided with a plurality of indicating areas corresponding to the position and number of the clamping grooves, and the colors in the plurality of indicating areas are different;

[0017] The rotating disc is fixedly provided with a shielding cover at one end away from the insulating connecting rod, the diameter of the shielding cover is consistent with the diameter of the rotating disc, and an observation area is formed between the inner ring of the shielding cover and the inner ring of the outer cover, and the in-place state of the movable contact is obtained by observing the color of the corresponding observation area part of the indicating rod

[0018] In this technical solution, the color of each indicating area corresponds to a position, for example, the area a is green, corresponding to the disconnecting position; the area b is red, corresponding to the closing position of the disconnecting switch; and the area c is yellow, corresponding to the closing position of the grounding switch; at this time, the in-place state of the movable contact can be known by observing the color of the corresponding observation area part of the indicating rod.

[0019] Compared with the prior art, the beneficial effects of the present application are:

[0020] 1. In the 252kV three-position switch with the last item indicating function, when the operating personnel manually drives the insulating connecting rod, the indicating rod can be temporarily clamped into the clamping groove to prevent the rotating disc from continuing to rotate, thereby providing the operating personnel with a body feedback, after the operating personnel finds it, the indicating rod can quickly separate from the clamping groove, so as to not affect the continuous rotation of the rotating disc. Moreover, the depths between part of the clamping grooves are different, so that the lengths of the indicating rod inserted into the clamping grooves are different, and the position of the movable contact is understood by identifying the inserted length, thereby providing the operating personnel with a visual feedback.

[0021] 2. In the 252kV three-position switch with the last item indicating function, different colors are arranged on the indicating rod, so that the indicating rod can not only block the rotation of the rotating disc to provide the operating personnel with a body feedback, but also quickly understand the position of the movable contact by observing the color displayed by the indicating rod at the observation area, thereby realizing the double redundant verification of the final position of the movable contact. DETAILED DESCRIPTION

[0022] Figure 1 is a cross-sectional schematic view of the overall structure of the present application;

[0023] Figure 2 is a structural schematic view of the last item indicating mechanism of the present application Figure 1 ;

[0024] Figure 3 is a structural schematic view of the last item indicating mechanism of the present application Figure 2 ;

[0025] Figure 4 is a structural schematic view of the indicating rod of the present application;

[0026] Figure 5 is a structure diagram of the rotary disc of the present application;

[0027] Figure 6 is a working state diagram of the rotary disc of the present application Figure 1 ;

[0028] Figure 7 is a position state diagram of the indicating rod of the present application;

[0029] Figure 8 is a structure diagram of the shielding cover of the present application;

[0030] Figure 9 is a working state diagram of the rotary disc of the present application Figure 2 .

[0031] The meanings of the respective reference numerals in the drawings are as follows:

[0032] 100, housing; 101, insulating connecting rod; 102, driving mechanism; 110, last indicating mechanism; 111, outer cover; 112, transparent cover; 113, shielding cover; 114, observation area; 120, indicating rod; 121, movable chamber; 122, compression spring; 123, indicating area; 124, first magnet; 130, rotary disc; 131, split slot; 132, bevel; 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 DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0035] In addition, the terms "first", "second", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0036] In view of the lack of double redundant verification of the final position of the moving contact, the present application provides a 252kV three-position switch with a last item indicating function, as shown in the accompanying drawings. Figure 1 The three-position switch includes an insulation connecting rod 101 for simultaneously driving the action of the moving contact of the three-phase switch, and the insulation connecting rod 101 is in transmission with the moving contact of the corresponding switch through the part located in the shell 100. The moving contact is a reciprocating linear motion, and the disconnector static contact and the grounding switch static contact in the shell 100 are located at both ends of the moving contact, i.e. the moving contact is in the middle position. This design realizes the logical interlocking of the disconnector and the grounding switch in structure, i.e. when the disconnector is in the closed position, the grounding switch must be in the open position, and similarly, when the grounding switch is in the closed position, the disconnector must be in the open position. If the conversion of the moving contact from the disconnector closed to the grounding switch closed is to be realized, the moving contact must be first moved from the disconnector closed position to the disconnector open position, and then moved to the grounding switch closed position.

[0037] The insulation connecting rod 101 is driven by a driving mechanism 102 arranged on one side of the shell 100. The driving mechanism 102 can be electric or manual, or electric and manual.

[0038] The three-position switch further includes a last item indicating mechanism 110 arranged on one side of the shell 100. As shown in the accompanying drawings, Figure 2 The last item indicating mechanism 110 includes an outer cover 111, an indicating rod 120 and a rotating disc 130. Among them, in combination with Figure 3The end of the outer cover 111 towards the shell 100 is an opening structure for the insulated connecting rod 101 to pass through, the opening end of the outer cover 111 is bent outwards, and the outer cover 111 is fixed at the position of the shell 100 corresponding to the end of the insulated connecting rod 101 through the bending part. The rotating disc 130 is in the outer cover 111 and is coaxially fixedly connected with the insulated connecting rod 101 through bolts, welding or clamping and the like, so that the rotating disc 130 can rotate synchronously with the insulated connecting rod 101. The outer ring of the rotating disc 130 is provided with a plurality of clamping grooves with different depths, and the plurality of clamping grooves correspond to the grounding switch closed position, the disconnector closed position and the open position respectively. The indicating rod 120 is slidingly arranged in the outer cover 111 and is provided at the bottom with an elastic member for driving the indicating rod 120. Under the elastic action of the elastic member, the indicating rod 120 is separated from the elastic member and temporarily enters the clamping groove, thereby temporarily limiting the rotation of the rotating disc 130. In addition, part of the clamping grooves are provided with a magnetic attraction assembly magnetically attracted to the indicating rod 120. Under the action of the magnetic attraction assembly, the indicating rod 120 extends into the different clamping grooves to different lengths, and the position of the current movable contact is obtained by observing the extension length of the indicating rod 120. Correspondingly, as shown in Figure 3 The end of the outer cover 111 is made of transparent material. In implementation, the end of the outer cover 111 is provided as an opening structure, and then the transparent cover 112 is connected to the opening end of the outer cover 111, so that the end of the outer cover 111 is transparent.

[0039] That is, when the operator manually drives the insulated connecting rod 101, the indicating rod 120 can be temporarily clamped into the clamping groove to prevent the rotating disc 130 from continuing to rotate, thereby providing the operator with a body feedback. After the operator finds it, the indicating rod 120 can quickly separate from the clamping groove, so as not to affect the continuous rotation of the rotating disc 130. In addition, the depths of part of the clamping grooves are different, so that the lengths of the indicating rod 120 extending into the clamping grooves are different, and the position of the movable contact is understood by identifying the extension length, thereby providing the operator with a visual feedback.

[0040] Specifically, the indicating rod 120 can be cylindrical, square columnar or other shapes. The present embodiment takes the cylindrical shape as an example to disclose the setting position of the indicating rod 120. As shown in Figure 4 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 a movable chamber 121 for the indicating rod 120 to slide. This design makes the indicating rod 120 in a vertical state and located at the middle and lower part of the outer cover 111, so that the elastic member pops up the indicating rod 120 upwards to enter the clamping groove, and when the kinetic energy of the indicating rod 120 disappears, the indicating rod 120 is reset by its own gravity.

[0041] Specifically, the elastic member is a compression spring 122 arranged at the bottom of the movable chamber 121, the top of the compression spring 122 is in contact with the bottom of the indicating rod 120, and the two are not connected. Then, as shown inFigure 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.

[0042] 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:

[0043] 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.

[0044] The two sides of the grounding groove 133 are respectively a first groove wall 134 and a second groove wall 135. When the indicating rod 120 enters the grounding groove 133, the first groove wall 134 is parallel to the indicating rod 120, so that the first groove wall 134 does not exert an action force on the indicating rod 120 to move to the compression spring 122, thereby realizing that the indicating rod 120 limits the rotation of the rotating disc 130 through the first groove wall 134. The second groove wall 135 always forms an angle with the indicating rod 120, that is, the second groove wall 135 is always inclined to the indicating rod 120. When the second groove wall 135 moves to the indicating rod 120, the second groove wall 135 guides the indicating rod 120 to leave the grounding groove 133.

[0045] The two sides of the isolation groove 136 are respectively a third groove wall 137 and a fourth groove wall 138. When the indicating rod 120 enters the isolation groove 136, the third groove wall 137 is parallel to the indicating rod 120, so that the third groove wall 137 does not exert an action force on the indicating rod 120 to move to the compression spring 122, thereby realizing that the indicating rod 120 limits the rotation of the rotating disc 130 through the third groove wall 137. The fourth groove wall 138 always forms an angle with the indicating rod 120, that is, the fourth groove wall 138 is always inclined to the indicating rod 120. When the fourth groove wall 138 moves to the indicating rod 120, the fourth groove wall 138 guides the indicating rod 120 to leave the grounding groove 133.

[0046] Therefore, the structures of the grounding groove 133 and the isolation groove 136 are basically the same. The main difference is that the grounding groove 133 and the isolation groove 136 are symmetrically arranged, and 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.

[0047] In combination with Figure 4 and Figure 5 , the magnetic attraction assembly includes a first magnet 124 and a second magnet 139. The first magnet 124 is fixedly arranged at the top end of the indicating rod 120, and the second magnet 139 is fixedly arranged at the inner end of the grounding groove 133 and the isolation groove 136. In this way, when the indicating rod 120 enters the grounding groove 133 or the isolation groove 136, the second magnet 139 can attract the indicating rod 120 to the inner end of the grounding groove 133 or the isolation groove 136 through the first magnet 124. Since the top end of the indicating rod 120 is at the inner end of the rotating disc 130 or the isolation groove 136, and the depths of the rotating disc 130 and the isolation groove 136 are different, the length of the indicating rod 120 extending into the rotating disc 130 or the isolation groove 136 is also different. In addition, the inner ends of the grounding groove 133 and the isolation groove 136 are both arc-shaped structures, which can always stably contact the indicating rod 120 during the rotation of the rotating disc 130.

[0048] Although the position of the movable contact can be observed by the length of the extension, in order to determine the position of the movable contact more intuitively and quickly, as shown in Figure 4 , the present application further provides three color-different indicating areas 123 on the outer ring of the indicating rod 120, the distribution positions of the three indicating areas 123 refer to the area a, area b and area c in Figure 7 , and the colors in the three indicating areas 123 are different, the color of each indicating area 123 corresponds to a position, for example, the area a is green, corresponding to the open position; the area b is red, corresponding to the closed position of the disconnector; and the area c is yellow, corresponding to the closed position of the grounding switch.

[0049] , and as shown in Figure 3 and Figure 8 , the rotating disc 130 is fixedly provided with a shielding cover 113 away from one end of the insulating connecting rod 101, the diameter of the shielding cover 113 is consistent with the diameter of the rotating disc 130, for shielding the open slot 131, the grounding slot 133 and the isolation slot 136. The area not shielded by the grounding slot 133 forms an observation area 114, i.e. the area between the inner ring of the shielding cover 113 and the inner ring of the outer cover 111, at this time, the color of the corresponding observation area 114 of the indicating rod 120 can be observed to know the position of the movable contact.

[0050] The working principle of the present application will be described in detail as follows:

[0051] , as shown in Figure 6 , when it is needed to move the movable contact to the open position, the operator rotates the insulating connecting rod 101, the insulating connecting rod 101 drives the rotating disc 130 to rotate along the arrow direction. When the indicating rod 120 abuts against the outer ring of the rotating disc 130, the compression spring 122 is compressed to store energy. When the open slot 131 rotates to the front of the indicating rod 120, the compression spring 122 will rebound quickly and push the indicating rod 120 to move, the indicating rod 120 is separated from the compression spring 122 under the action of inertia and enters the open slot 131, if the rotating disc 130 continues to rotate at this time, the indicating rod 120 will be clamped in the open slot 131 to stop the rotation of the rotating disc 130, which is equivalent to providing the operator with a body feedback. Then referring to Figure 7 , when the rotating disc 130 stops rotating, the compression spring 122 falls back to the top of the compression spring 122 by its own gravity, and then referring to Figure 8 , the area a is at the observation area 114, and the operator sees the area a to indicate that the movable contact is at the open position.

[0052] , as shown in Figure 9As shown, when the moving contact needs to be moved to the position of the disconnecting switch closing, the operator rotates the insulating connecting rod 101, and 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 indicating rod 120, the compression spring 122 pushes the indicating rod 120 into the isolation groove 136, at the same time, the second magnet 139 attracts the top end of the indicating rod 120, when the rotating disc 130 continues to rotate, the indicating rod 120 in the second magnet 139 will stop the rotation of the rotating disc 130 through the third groove wall 137, and provide the operator with the body feedback. At this time, the area a is at the observation area 114, and the operator sees the color of the area b, which indicates that the moving contact is in the position of the disconnecting switch closing. When the disconnecting switch needs to be opened, refer to the right half of the figure in the description Figure 9 , the rotating disc 130 pushes the indicating rod 120 downward through the fourth groove wall 138, so that the top end of the indicating rod 120 abuts against the outer ring of the rotating disc 130.

[0053] The principle of the moving contact moving to the position of the grounding switch closing is consistent with the principle of the moving contact moving to the position of the disconnecting switch closing, which is not described here.

[0054] In summary, by setting different colors on the indicating rod 120, the indicating rod 120 can not only block the rotation of the rotating disc 130 to improve the body feedback for the operator, but also quickly understand the position of the moving contact by observing the color displayed by the indicating rod 120 at the observation area 114, so as to realize the double redundant verification of the final position of the moving contact.

[0055] The basic principle, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, the above examples and descriptions in the specification are only preferred examples of the present application, and are not used to limit the present application, various changes and improvements of the present application can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A 252 kV three-position switch with last item indication function, comprising an insulation connecting rod (101) for simultaneously driving the action of the moving contact of the three-phase switch, the insulation connecting rod (101) is in transmission with the moving contact of the corresponding switch through the part located in the shell (100); characterized in that: Also include the last item indicating mechanism (110) set on one side of the shell (100), the last item indicating mechanism (110) including cover (111), rotating disc (130) and indicating rod (120); The cover (111) is fixed on the corresponding end of the insulated connecting rod (101) of the shell (100); The rotating disc (130) is coaxially fixedly connected in the cover (111) and the insulated connecting rod (101); the outer ring of the rotating disc (130) is provided with a plurality of clamping grooves with different depths, and the plurality of clamping grooves correspond to the grounding switch closing position, the isolating switch closing position and the opening position respectively; The indicating rod (120) is slidingly arranged in the cover (111) and is provided at the bottom with an elastic member for driving the indicating rod (120); under the elastic action of the elastic member, the indicating rod (120) is separated from the elastic member and temporarily enters the clamping groove, thereby temporarily limiting the rotation of the rotating disc (130); Part of the clamping grooves are provided with magnetic attraction assemblies magnetically attracted to the indicating rod (120); under the action of the magnetic attraction assemblies, the indicating rod (120) extends into different clamping grooves with different lengths, and the position of the current movable contact is obtained by observing the extension length of the indicating rod (120); The clamping groove includes an opening groove (131), a grounding groove (133) and an isolation groove (136); The opening groove (131) corresponds to the opening position of the movable contact, the grounding groove (133) corresponds to the grounding switch closing position of the movable contact, and the isolation groove (136) corresponds to the isolating switch closing position of the movable contact; The opening ends of the opening groove (131) on both sides are outwardly expanded to form bevels (132), and the height of the connection between the bevel (132) and the side wall of the opening groove (131) is higher than the top height of the indicating rod (120) supported by the compression spring (122); One of the groove walls of the grounding groove (133) and the isolation groove (136) is parallel to the indicating rod (120), and the other groove wall always has an included angle with the indicating rod (120); The grounding groove (133) and the isolation groove (136) are symmetrically arranged between the grounding groove (133) and the isolation groove (136); the depths of the grounding groove (133) and the isolation groove (136) are different.

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

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

4. The 252 kV three-position switch with last item indication function according to claim 3, characterized in that: The elastic member is a compression spring (122) arranged at the bottom of the movable chamber (121); the top of the compression spring (122) is in contact with the bottom of the indicating rod (120); under the support of the compression spring (122), the top end height of the indicating rod (120) is higher than the bottom height of the rotating disc (130).

5. The 252 kV three-position switch with last item indication function according to claim 1, characterized in that: The magnetic attraction assembly comprises a first magnet (124) and a second magnet (139) that are magnetically attracted to each other, the first magnet (124) is fixedly arranged at the top end of the indicating rod (120), and the second magnet (139) is fixedly arranged at the inner end of the grounding groove (133) and the isolation groove (136).

6. The 252 kV three-position switch with last item indication function according to claim 1, characterized in that: The outer ring of the indicating rod (120) is provided with a plurality of indicating areas (123) corresponding in position and number to the clamping grooves, and the colors in the plurality of indicating areas (123) are different; The rotating disc (130) is fixedly arranged at one end away from the insulating connecting rod (101) with a shielding cover (113), the diameter of the shielding cover (113) is consistent with the diameter of the rotating disc (130), and an observation area (114) is formed between the inner ring of the shielding cover (113) and the inner ring of the outer cover (111), and the to-position state of the moving contact is obtained by observing the color of the corresponding observation area (114) of the indicating rod (120).

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