An insulated three-position load switch structure

Abstract

This invention relates to the field of load switch technology and discloses an insulated three-position load switch structure, including an upper shield, a connecting part and a switching part on the upper shield, an arc-extinguishing part, a closing part, a tripping control part and a grounding part disposed within the connecting part, and a lower shield, which contains three positions: a switching part installed within the connecting part for position switching; an arc-extinguishing part disposed on the upper shield for supplying SF gas; a closing part disposed within the position of the lower shield for circuit connection and tripping contact; and a tripping control part disposed within the position of the lower shield for synchronous triggering of tripping and grounding. The design employs a linkage between the tripping control part and the grounding part, with the switching plate synchronously driving the limit rod. During tripping, the grounding contact plate and the grounding contact momentarily contact each other, promptly grounding any remaining charge in the line, thus completely eliminating the risk of electric shock during maintenance and resolving the safety hazards of traditional step-by-step triggering.

Description

Technical Field

[0001] This invention relates to the field of load switch technology, specifically to an insulated three-position load switch structure. Background Technology

[0002] Currently available FLN36-12 series sulfur hexafluoride load switches rely on independent mechanical transmission components for their core three-position on / off control. The conventional design involves a single operating shaft driving the moving contact to rotate, sequentially switching between the closing, opening, and grounding positions. Theoretically, this requires strict interlocking between these positions: the closing position only connects the main circuit, the opening position disconnects the main circuit, and the grounding position only connects the grounding circuit when the switch is open.

[0003] However, existing structures mostly adopt a single-path transmission and simple mechanical limit design, without making special optimizations for the linkage requirements of simultaneous closing and grounding conduction when the circuit breaker is opened. This makes the logic reliability of the workstation switching dependent on the accuracy and wear of the transmission components, which may lead to subsequent functional failures.

[0004] In traditional designs, the opening and closing of the circuit breaker and the grounding are triggered in steps rather than synchronously. When the operating mechanism switches from closing to opening, the closing contact must be disconnected first, and then the grounding contact must be closed separately. This process involves a brief window period where the circuit breaker is in place but the grounding is not conducting. If there is residual charge in the line, it can easily lead to the risk of electric shock to personnel.

[0005] The sealing structure of the closing contact and insulating gas chamber of the partial load switch is simple. When it is in the closing position, if the seal is aged or the assembly is incorrect, it will cause the internal sulfur hexafluoride gas to leak. This will not only reduce the insulation performance of the main circuit, but may also affect the subsequent arc extinguishing effect due to insufficient gas pressure, indirectly destroying the basic logic that the circuit breaker and grounding are disconnected when closing.

[0006] When inspecting a line, if the grounding is not connected in time after the switch is opened, the maintenance personnel may mistakenly believe that the line is de-energized and work there, and may be electrocuted by induced charges. If the grounding is not completely disconnected when the switch is closed, it will cause a short circuit between the main circuit and the grounding circuit, resulting in the switch burning out and the line tripping, which will seriously affect the reliability of power supply. Summary of the Invention

[0007] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an insulated three-position load switch structure, which solves the problem that the opening and closing of the traditional load switch is mostly triggered in steps rather than synchronously, resulting in a brief window period where the switch is in place but the grounding is not connected, thus affecting operational safety.

[0008] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an insulated three-position load switch structure, comprising an upper shield, a connecting part and a switching part disposed on the upper shield, an arc-extinguishing part, a closing part, a tripping control part and a grounding part disposed within the connecting part, and a lower shield, wherein the lower shield has three positions disposed therein: a switching part, installed within the connecting part for position switching; an arc-extinguishing part disposed on the upper shield for supplying SF gas; a closing part disposed within the positions of the lower shield for circuit connection and tripping contact; a tripping control part disposed within the positions of the lower shield for synchronous triggering of tripping and grounding; and a grounding part disposed within the connecting part for circuit connection and grounding.

[0009] Preferably, a contact seat for opening the circuit breaker is installed in the middle of the lower shield, and a contact seat for closing the circuit breaker and a contact seat for grounding are installed in the other two positions of the lower shield, respectively. A positioning plate three and a switching plate are installed in the position where the grounding contact seat is located. The positioning plate three has an L-shaped structure, and the switching plate has a U-shaped structure. One side of the switching plate is slidably connected to the positioning plate three.

[0010] Preferably, the tripping control unit includes a tripping contact, which is connected to a tripping contact seat. A tripping contact piece is installed on the tripping contact. Support arm one and support arm three are fixedly connected in the middle of the lower shield. A sector gear is rotatably connected to support arm one via a gear shaft. A closing piece is connected to the side of the sector gear away from the meshing teeth. Support arm two is hinged to the sector gear. Support arm two is hinged to the tripping piece. A rotating shaft is rotatably connected to support arm three. A hollow gear is fixedly sleeved on the rotating shaft. A bevel gear one is fixedly sleeved at one end of the rotating shaft. A bevel gear two meshes with bevel gear one. Bevel gear two is fixedly sleeved at the other end of the drive rod.

[0011] Preferably, the switch part includes a mechanism connecting plate integrally connected to one end of the upper shielding cover. The mechanism connecting plate has a switch through hole, and a drive rod is rotatably connected inside the switch through hole. A switch lever is installed at one end of the drive rod. The mechanism connecting plate also has a passage opening and an injection port. The switch lever is located outside the mechanism connecting plate. A sliding sleeve is installed on the mechanism connecting plate, and a locking block is slidably connected inside the sliding sleeve. A return spring is elastically connected between the locking block and the inner wall of the sliding sleeve. The end of the locking block has an arc surface structure and contacts the switch lever.

[0012] Preferably, the arc extinguishing unit includes an air storage tank that matches the three stations of the lower shield. One of the air storage tanks is connected to an air injection pipe, the end of which extends into the injection port and is equipped with a one-way air inlet valve. A connecting pipe is connected between every two air storage tanks, and the other air storage tank is connected to an air outlet pipe.

[0013] Preferably, the closing part includes a closing contact, which is mounted on a closing contact seat. Positioning plate one and positioning plate two are installed on the side of the lower shield. Positioning plate one is fixedly connected to the closing contact, and a baffle is fixedly connected to positioning plate two.

[0014] Preferably, a circuit contact is installed in the middle of the lower shielding cover, the circuit contact is in contact with one side of the switch plate, one end of the circuit contact is connected to an arc extinguishing grid plate, an electromagnetic coil is installed between the circuit contact and the baffle, an iron core column is slidably connected to the circuit contact, and a spring is elastically connected between the iron core column and the circuit contact.

[0015] Preferably, both the first positioning piece and the second positioning piece are U-shaped structures, the end of the iron core column abuts against the baffle, and the end of the electromagnetic coil extends along the surface of the second positioning piece and is wound around the closing contact.

[0016] Preferably, the grounding part includes a transposition piece, which is installed on the other side of the lower shield. The transposition piece has a U-shaped structure. An energizing contact is installed in the passageway. The energizing contact is fixedly connected to one ear end of the transposition piece. A limit rod is fixedly connected to the other ear end of the transposition piece. Both ears of the transposition piece are provided with limit holes corresponding to the limit rods. The limit rod slides through the limit hole on one ear end of the transposition piece and is fixedly connected to a grounding contact.

[0017] Preferably, the grounding contact piece has an L-shaped structure, and a spring is elastically connected between the grounding contact piece and the switching piece. The ear end of the switching piece contacts the ear end of the switching piece. A grounding contact is installed on the grounding contact base, and a grounding copper busbar is installed on the grounding contact. The grounding copper busbar is also installed in the working position of the lower shield.

[0018] (III) Beneficial Effects Compared with the prior art, the present invention provides an insulated three-position load switch structure, which has the following beneficial effects: 1. The structure of this insulated three-position load switch adopts a linkage design between the tripping control unit and the grounding unit. The switching plates synchronously drive the limit rod. When the switch is tripped, the grounding contact plate and the grounding contact make instantaneous contact, and the residual charge of the line is promptly conducted to the ground, completely eliminating the risk of electric shock during maintenance and solving the safety hazards of traditional step-triggered circuits.

[0019] 2. The structure of this insulated three-position load switch uses a locking block and a reset spring in the switch section to lock the closing and opening positions, preventing rotation after operation. Each component forms a rigid transmission through gears, support arms, and positioning plates, avoiding the accuracy dependence problem of traditional single-path transmission, ensuring that the position switching is smooth and without misalignment, and eliminating short circuit accidents caused by grounding failure during closing.

[0020] 3. The structure of this insulated three-position load switch adopts a shielding cover assembly and an arc-extinguishing section to form a sealed gas chamber, reducing SF6 gas leakage and ensuring insulation performance. The multiple gas storage tanks and through-pipe design of the arc-extinguishing section achieve uniform gas distribution. Combined with the arc-extinguishing grid to divide the arc, the arc duration is shortened, contact erosion is reduced, and the service life of core components such as closing contacts and opening contacts is extended.

[0021] 4. This insulated three-position load switch structure adopts a one-button switching method for closing, opening and grounding via switch levers, eliminating the need for separate operation of the grounding component. The gas injection pipe and one-way gas inlet valve of the arc extinguishing section facilitate SF gas replenishment without disassembling the overall structure, thus reducing maintenance costs and difficulty. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of an insulated three-position load switch proposed in this invention; Figure 2 This is a schematic diagram of the structure of the connecting part of the present invention; Figure 3 For the present invention Figure 2 Enlarged view of A in the middle; Figure 4 This is a schematic diagram of the internal structure of the lower shield of the present invention; Figure 5 This is a schematic diagram of the arc-extinguishing part of the present invention; Figure 6 This is a schematic diagram of the closing section of the present invention; Figure 7 This is a schematic diagram of the structure of the iron core column of the present invention; Figure 8 This is a diagram showing the connection between the tripping control unit, the grounding unit, and the switching unit of the present invention. Figure 9 For the present invention Figure 8 Enlarged view of B in the middle; Figure 10 This is a schematic diagram of the grounding part of the present invention.

[0023] In the diagram: 1. Upper shielding cover; 2. Connecting part; 21. Lower shielding cover; 22. Closing contact seat; 23. Opening contact seat; 24. Grounding contact seat; 3. Switching part; 31. Mechanism connecting plate; 32. Passage port; 33. Injection port; 34. Drive rod; 35. Switch lever; 36. Sliding sleeve; 37. Locking block; 4. Arc extinguishing part; 41. Gas tank; 42. Gas injection pipe; 43. One-way air inlet valve; 44. Through pipe; 45. Gas outlet pipe; 5. Closing part; 51. Closing contact; 52. Positioning plate one; 53. Positioning plate two; 54. Baffle; 55. Circuit. 56. Contact piece; 57. Arc extinguishing grid plate; 58. Electromagnetic coil; 59. Iron core column; 60. Spring 1; 61. Tripping control unit; 62. Tripping contact; 63. Support arm 1; 64. Sector gear; 65. Closing plate; 66. Support arm 2; 67. Switching plate; 68. Positioning plate 3; 69. Support arm 3; 610. Rotating shaft; 611. Hollow sleeve gear; 612. Bevel gear 1; 613. Bevel gear 2; 7. Grounding part; 71. Switching plate; 72. Energizing contact; 73. Limit rod; 74. Grounding contact piece; 75. Spring 2; 76. Grounding contact. Detailed Implementation

[0024] The technical solutions of 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.

[0025] Please see Figure 1 - Figure 10 This invention provides an insulated three-position load switch structure, including an upper shield 1, a connecting part 2 and a switching part 3 on the upper shield 1, and an arc extinguishing part 4, a closing part 5, a tripping control part 6 and a grounding part 7 inside the connecting part 2. The connecting part 2 serves as the protection and installation carrier of the overall structure. The independent station design achieves physical isolation of each station, avoids interference between components, and isolates external dust and moisture from erosion of internal components. The connecting part 2 includes a lower shield 21, which has three stations. The middle station of the lower shield 21 is equipped with a tripping contact seat 23, and the other two stations of the lower shield 21 are respectively equipped with a closing contact seat 22 and a grounding contact seat 24.

[0026] In this invention, the switch unit 3 serves as the core of human-machine interaction and transmission connection, realizing workstation switching, mechanically limiting and locking the position of each workstation to prevent rotation and accidental touch after operation, and ensuring the stability of the workstation state. The switch unit 3 includes a mechanism connecting plate 31, which is integrally connected to one end of the upper shielding cover 1. The mechanism connecting plate 31 has a switch through hole, and a drive rod 34 is rotatably connected in the switch through hole. A switch lever 35 is installed at one end of the drive rod 34. The mechanism connecting plate 31 also has a passage 32 and an injection port 33. The switch lever 35 is located outside the mechanism connecting plate 31. A sliding sleeve 36 is installed on the mechanism connecting plate 31. A locking block 37 is slidably connected in the sliding sleeve 36. A return spring is elastically connected between the locking block 37 and the inner wall of the sliding sleeve 36. The end of the locking block 37 has an arc surface structure and contacts the switch lever 35.

[0027] Furthermore, the arc-extinguishing section 4 provides a stable supply of SF6 gas and arc-extinguishing medium. The SF6 gas is evenly distributed, balancing the pressure in the gas chamber and preventing damage to components due to excessive pressure. The arc-extinguishing section 4 includes gas storage tanks 41 that match the three stations of the lower shield 21. One of the gas storage tanks 41 is connected to an injection pipe 42. The end of the injection pipe 42 extends into the injection port 33 and is equipped with a one-way inlet valve 43. A connecting pipe 44 connects every two gas storage tanks 41, and another gas storage tank 41 is connected to an outlet pipe 45.

[0028] In this embodiment, the tripping control unit 6 serves as the core transmission hub for station switching, achieving synchronous linkage between tripping and grounding. During tripping, the grounding action is triggered synchronously to ensure displacement accuracy and prevent transmission jamming. The tripping control unit 6 includes a tripping contact 61 connected to a tripping contact seat 23. A tripping contact piece 62 is mounted on the tripping contact 61. Support arm 1 63 and support arm 3 69 are fixedly connected within the station in the middle of the lower shield 21. A sector gear 64 is rotatably connected to support arm 1 63 via a gear shaft. A closing piece 65 is connected to the side of the sector gear 64 away from the meshing teeth. Support arm 2 66 is hinged to 64. Switching plate 67 is connected to support arm 2 66. Positioning plate 3 68 is installed in the station where grounding contact seat 24 is located. Positioning plate 3 68 has an L-shaped structure. Switching plate 67 has a U-shaped structure. One ear end of switching plate 67 is slidably connected to positioning plate 3 68. Rotary shaft 610 is rotatably connected to support arm 3 69. Hollow gear 611 is fixedly sleeved on rotating shaft 610. Bevel gear 1 612 is fixedly sleeved on one end of rotating shaft 610. Bevel gear 2 613 meshes on bevel gear 1 612. Bevel gear 2 613 is fixedly sleeved on the other end of drive rod 34.

[0029] It is worth noting that the closing section 5 achieves the dual functions of main circuit conduction and opening trigger. When closing, it forms a circuit; when opening, it cuts off the main circuit and cooperates with the arc extinguishing section 4 to accelerate arc extinguishing and prevent arc erosion of the contacts. The closing section 5 includes a closing contact 51, which is mounted on a closing contact seat 22. Positioning plate 1 52 and positioning plate 2 53 are installed on the side of the lower shield 21. Positioning plate 1 52 is fixedly connected to the closing contact 51. A baffle 54 is fixedly connected to the positioning plate 2 53. A circuit contact is installed in the middle of the lower shield 21. The circuit contact 55 is in contact with one side of the switch plate 67. One end of the circuit contact 55 is connected to the arc extinguishing grid plate 56. An electromagnetic coil 57 is installed between the circuit contact 55 and the baffle 54. An iron core column 58 is slidably connected to the circuit contact 55. A spring 59 is elastically connected between the iron core column 58 and the circuit contact 55. Positioning plate 52 and positioning plate 53 are both U-shaped structures. The end of the iron core column 58 abuts against the baffle 54. The end of the electromagnetic coil 57 extends along the surface of positioning plate 53 and is wound around the closing contact 51.

[0030] It is worth noting that the grounding part 7 achieves synchronous conduction of the grounding circuit after the circuit breaker is tripped. When the circuit breaker is tripped, the residual charge of the line is conducted to the ground. The grounding part 7 includes a transducer piece 71, which is installed on the other side of the lower shield 21. The transducer piece 71 has a U-shaped structure, and an energized contact 72 is installed in the passage 32. The energized contact 72 is fixedly connected to one ear end of the transducer piece 71. A limit rod 73 is fixedly connected to the other ear end of the transducer piece 67. Both ears of the transducer piece 71 are open. A limiting hole corresponding to the limiting rod 73 is provided. The limiting rod 73 slides through the limiting hole at one end of the transducer plate 71 and is fixedly connected to a grounding contact plate 74. The grounding contact plate 74 has an L-shaped structure. A spring 75 is elastically connected between the grounding contact plate 74 and the transducer plate 71. The end of the transducer plate 67 contacts the end of the transducer plate 71. A grounding contact 76 is installed on the grounding contact seat 24. A grounding copper busbar is installed on the grounding contact 76. The grounding copper busbar is also installed in the working position of the lower shield 21.

[0031] Working principle: The contact seat is used to connect the fuse. When the switch lever 35 is not under force, the locking block 37 in the sliding sleeve 36 pops out under the action of the reset spring. The end arc surface is in contact with the surface of the switch lever 35 to form an initial limit. One ear of the switching piece 67 contacts the circuit contact piece 55, and the other ear rests on the initial ear of the switching piece 71. The limit rod 73 does not pull the grounding contact piece 74. The grounding contact piece 74 remains disconnected from the grounding contact 76 under the support of the second spring 75.

[0032] When the electromagnetic coil 57 is not energized, the iron core column 58, under the elastic force of the spring 59, abuts against the baffle 54 at its end, and does not generate a thrust on the switching plate 67. The three gas storage tanks 41 of the arc extinguishing section 4 are connected through the connecting pipe 44, and the sulfur hexafluoride gas filled inside the load switch is kept at the rated pressure through the gas outlet pipe 45. The one-way gas inlet valve 43 of the gas injection pipe 42 is closed to ensure that there is no gas leakage, thus providing the insulation and arc extinguishing medium foundation for subsequent arc extinguishing.

[0033] When the main circuit is connected, the current passes through the closing contact 51 to the electromagnetic coil 57, to the circuit contact 55 to the switching piece 67, and then to the switching piece 71 to the energizing contact 72 to form a circuit. When the circuit is opened, a large instantaneous current is passed through the electromagnetic coil 57, generating a strong magnetic field that pulls the iron core column 58 to overcome the elastic force of the spring 59 and pushes the switching piece 67 to slide along the positioning piece 68, so that the ear end of the switching piece 67 on one side is quickly separated from the circuit contact 55, the main circuit is cut off, and the circuit is opened. The sulfur hexafluoride gas, together with the arc extinguishing grid 56, accelerates the cooling and extinguishing of the arc.

[0034] When the switching plate 67 slides, its other ear end simultaneously pulls the limit rod 73, causing the limit rod 73 to slide along the limit hole of the switching plate 71, which drives the grounding contact 74 to overcome the elastic force of the spring 75 and move towards the grounding contact 76 until they make close contact. The grounding copper busbar introduces the charge into the ground, eliminating the risk of electric shock.

[0035] The shifting of the switch plate 67 drives the second support arm 66 to push the sector gear 64 to rotate, which in turn drives the empty sleeve gear 611, the rotating shaft 610, and the first bevel gear 612 and the second bevel gear 613 to rotate. This causes the switch plate 35 to rotate and press the locking block 37. The locking block 37 slides along the sliding sleeve 36 and is reset under the force of the reset spring, thereby limiting the rotation of the switch plate 35 and preventing it from switching to the closing state. At this time, no closing occurs after the circuit is opened, and the connection between the circuit breaker and the ground is ensured.

[0036] Conversely, pressing the card block 37 resets the rotary switch lever 35, releasing the spring 75 and pushing the grounding contact 74 to reset, thereby disconnecting the grounding contact 76 from the grounding contact 74. The switch plate 67 then re-engages with the circuit contact 55 and remains connected to the energized contact 72. At this time, closing the circuit breaker will not result in opening or grounding.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. An insulated three-position load switch structure, comprising an upper shield (1), characterized in that: The upper shield (1) is provided with a connecting part (2), the connecting part (2) includes a lower shield (21), and the lower shield (21) is provided with three workstations; The switch part (3) is installed inside the connecting part (2) and is used to realize the switching of work positions; The arc-extinguishing part (4) is installed on the upper shield (1) and is used to supply SF6 gas; The closing section (5) is located inside the lower shield (21) and is used for circuit connection and circuit opening triggering. The tripping control unit (6) is installed in the work position of the lower shield (21) and is used for the synchronous triggering of tripping and grounding. The grounding part (7) is set inside the connecting part (2) and is used for circuit conduction and grounding. The middle station of the lower shield (21) is equipped with a contact seat (23) for opening the circuit. The other two stations of the lower shield (21) are respectively equipped with a contact seat (22) for closing the circuit and a contact seat (24) for grounding. The station where the grounding contact seat (24) is located is equipped with a positioning piece three (68) and a switching piece (67). The positioning piece three (68) is an L-shaped structure and the switching piece (67) is a U-shaped structure. One side of the switching piece (67) is slidably connected to the positioning piece three (68). The switch part (3) includes a mechanism connecting plate (31). The mechanism connecting plate (31) is integrally connected to one end of the upper shield (1). The mechanism connecting plate (31) is provided with a switch through hole. A drive rod (34) is rotatably connected inside the switch through hole. One side of the drive rod (34) is connected to the switch through hole. A switch lever (35) is installed at the end. A passageway (32) and an injection port (33) are also provided on the mechanism connecting plate (31). The switch lever (35) is located outside the mechanism connecting plate (31). A sliding sleeve (36) is installed on the mechanism connecting plate (31). A locking block (37) is slidably connected inside the sliding sleeve (36). A return spring is elastically connected between the locking block (37) and the inner wall of the sliding sleeve (36). The end of the locking block (37) is an arc surface structure and contacts the switch lever (35). The closing part (5) includes a closing contact (51). The closing contact (51) is installed on the closing contact seat (22). A positioning piece one (52) and a positioning piece two (53) are installed on the side of the lower shield (21). The positioning piece one (52) is fixedly connected to the closing contact (51). A baffle (54) is fixedly connected to the positioning piece two (53).

2. The structure of an insulated three-position load switch according to claim 1, characterized in that: The tripping control unit (6) includes a tripping contact (61), which is connected to a tripping contact seat (23). A tripping contact piece (62) is installed on the tripping contact (61). A support arm one (63) and a support arm three (69) are fixedly connected in the middle of the lower shield (21). A sector gear (64) is rotatably connected to the support arm one (63) via a gear shaft. A closing piece (65) is connected to the side of the sector gear (64) away from the meshing teeth. A second support arm (66) is hinged to the gear (64), the second support arm (66) is hinged to the brake pad (67), a rotating shaft (610) is rotatably connected to the third support arm (69), a hollow gear (611) is fixedly sleeved on the rotating shaft (610), a first bevel gear (612) is fixedly sleeved on one end of the rotating shaft (610), a second bevel gear (613) meshes on the first bevel gear (612), and the second bevel gear (613) is fixedly sleeved on the other end of the drive rod (34).

3. The structure of an insulated three-position load switch according to claim 2, characterized in that: The arc extinguishing part (4) includes three gas storage tanks (41) that match the three stations of the lower shield (21). One of the gas storage tanks (41) is connected to an injection pipe (42). The end of the injection pipe (42) extends into the injection port (33) and is equipped with a one-way air inlet valve (43). A connecting pipe (44) is connected between every two gas storage tanks (41). The other gas storage tank (41) is connected to an outlet pipe (45).

4. The structure of an insulated three-position load switch according to claim 3, characterized in that: A circuit contact (55) is installed in the middle of the lower shield (21). The circuit contact (55) is in contact with one side of the switch plate (67). One end of the circuit contact (55) is connected to an arc-extinguishing grid plate (56). An electromagnetic coil (57) is installed between the circuit contact (55) and the baffle (54). An iron core column (58) is slidably connected to the circuit contact (55). A spring (59) is elastically connected between the iron core column (58) and the circuit contact (55).

5. The structure of an insulated three-position load switch according to claim 4, characterized in that: Both the first positioning piece (52) and the second positioning piece (53) are U-shaped structures. The end of the iron core column (58) abuts against the baffle (54). The end of the electromagnetic coil (57) extends along the surface of the second positioning piece (53) and is wound around the closing contact (51).

6. The structure of an insulated three-position load switch according to claim 5, characterized in that: The grounding part (7) includes a transposition piece (71), which is installed on the other side of the lower shield (21). The transposition piece (71) is a U-shaped structure. An energizing contact (72) is installed in the passage (32). The energizing contact (72) is fixedly connected to one side of the transposition piece (71). A limit rod (73) is fixedly connected to the other side of the transposition piece (67). Both sides of the transposition piece (71) are provided with limit holes corresponding to the limit rod (73). The limit rod (73) slides through the limit hole on one side of the transposition piece (71) and is fixedly connected to a grounding contact piece (74).

7. The structure of an insulated three-position load switch according to claim 6, characterized in that: The grounding contact (74) has an L-shaped structure. A spring (75) is elastically connected between the grounding contact (74) and the switching piece (71). The ear end of the switching piece (67) contacts the ear end of the switching piece (71). A grounding contact (76) is installed on the grounding contact seat (24). A grounding copper busbar is installed on the grounding contact (76). The grounding copper busbar is also installed in the working position of the lower shield (21).

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