On-load tap changer

Abstract

This on-load tap changer has an upper-stage shaft, a lower-stage shaft, and a power regulating unit. An upper end section of the lower-stage shaft is disposed outside an insulating oil. The upper-stage shaft can be attached / detached to / from the upper end section of the lower-stage shaft and is disposed outside the insulating oil. The power regulating unit is provided to the upper-stage shaft and regulates the transmission of power that exceeds a predetermined value.

Description

[Technical field]

[0001] An embodiment of the present invention relates to an on-load tap changer. [Background technology]

[0002] On-load tap changers change taps while the transformer is in operation, and there is a demand for on-load tap changers that require less maintenance man-hours. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 106065 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an on-load tap changer capable of reducing the number of maintenance steps. [Means for solving the problem]

[0005] The on-load tap changer of the embodiment includes a lower shaft, an upper shaft, a power regulating unit, A gear case of the gear mechanism; The lower shaft has an upper end portion disposed outside the insulating oil. The upper shaft is detachably attached to an upper end portion of the lower shaft and is disposed outside the insulating oil. The power regulating unit is provided on the upper shaft and regulates the transmission of power exceeding a predetermined value. A gear case of the gear mechanism houses the lower shaft and the upper shaft. The gear case of the gear mechanism is integrally formed. The upper shaft is detachable from the gear case of the gear mechanism. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a perspective view of an on-load tap changer according to an embodiment; [Diagram 2] FIG. 2 is a cross-sectional view of the top half of an on-load tap changer. [Diagram 3]Cross-sectional view of a gear mechanism. [Figure 4] FIG. [Diagram 5] 4 is a cross-sectional view taken along line VV in FIG. 3 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an on-load tap changer according to an embodiment will be described with reference to the drawings. FIG 1 is a perspective view of an on-load tap changer according to an embodiment. The on-load tap changer 10 changes taps during operation of the transformer. The on-load tap changer 10 is disposed inside the tank 5 of the transformer body 1. The on-load tap changer 10 is inserted into the tank 5 through an opening 5a in the top surface of the tank 5.

[0008] The on-load tap changer 10 has a tap selector 11 and a diverter switch 12. The tap selector 11 selects a tap of the transformer. The diverter switch 12 switches the circuit to the selected tap. The tap selector 11 is arranged in the lower half of the on-load tap changer 10, and the diverter switch 12 is arranged in the upper half. The diverter switch 12 is arranged inside an oil tank 20.

[0009] FIG. 2 is a cross-sectional view of the upper half of the on-load tap changer 10. The oil tank 20 has an oil tank body 22, an oil tank head 24, an oil tank lid 25, and a flange 27. The oil tank body 22 is cylindrical. The lower end of the oil tank body 22 is closed by a bottom plate. The oil tank head 24 is connected to the upper end of the oil tank body 22. The upper end of the oil tank head 24 is open. The oil tank lid 25 closes the opening at the upper end of the oil tank head 24. The oil tank 20 is sealed, and the second insulating oil 21 is filled inside the oil tank 20. The oil tank lid 25 is detachable from the oil tank head 24. The flange 27 is formed integrally with the oil tank head 24. The flange 27 extends radially outward from the outer periphery of the oil tank head 24. The flange 27 closes the opening 5a of the tank 5. The tank 5 is sealed, and the first insulating oil 6 is filled inside the tank 5. The first insulating oil 6 and the second insulating oil 21 have high electrical insulation properties and arc-extinguishing properties.

[0010] As shown in FIG. 1, the on-load tap changer 10 includes a gear mechanism 30, a drive shaft 14, and a power introduction section 15. The gear mechanism 30 reduces the speed of the power generated by an electric operation mechanism (not shown) and transmits it to the drive shaft 14. The gear mechanism 30 is disposed radially outside the oil vat head 24 and fixed to the flange 27. The gear mechanism 30 will be described in detail later.

[0011] 2, the upper end of the drive shaft 14 is connected to the gear mechanism 30. The drive shaft 14 extends downward from the gear mechanism 30. The drive shaft 14 approaches the oil vat body 22 as it extends downward. The lower end of the drive shaft 14 is connected to the power introduction section 15.

[0012] 1, the power introduction section 15 is disposed between the oil tank 20 and the tap selector 11. The power introduction section 15 introduces the power transmitted from the drive shaft 14 to the changeover switch 12 and the tap selector 11. The changeover switch 12 and the tap selector 11 are operated by the power transmitted from the drive shaft 14.

[0013] The maintenance work of the change-over switch 12 will now be described. The oil tank lid 25 is removed from the oil tank head 24 shown in Fig. 2. The second insulating oil 21 is drained (recovered) from inside the oil tank 20. The change-over switch 12 is pulled upward from the upper opening of the oil tank head 24. The maintenance work of the change-over switch 12 is carried out outside the tank 5. In some cases, inspection work of the change-over switch 12 is carried out while the change-over switch 12 is still placed inside the oil tank 20.

[0014] The change-over switch 12 is accommodated inside the oil tank 20. Therefore, it is possible to pull up the change-over switch 12 by simply draining the second insulating oil 21 from the oil tank 20, without draining the first insulating oil 6 from the tank 5. The gear mechanism 30 is fixed to the flange 27, and is not fixed to the oil tank lid 25. Therefore, it is possible to remove the oil tank lid 25 and perform maintenance work on the change-over switch 12 without removing the gear mechanism 30. As a result, the number of maintenance steps for the change-over switch 12 is reduced. In addition, the structure of the oil tank head 24 is simplified, and parts costs are reduced.

[0015] The gear mechanism 30 will now be described in detail. 3 is a cross-sectional view of the gear mechanism. The gear mechanism 30 is inserted into the through hole of the flange 27 and fixed around the through hole. The gear mechanism 30 seals the through hole of the flange 27. The gear mechanism 30 has a worm 31, a worm wheel 32, an upper shaft 40, a lower shaft 46, a tap display mechanism 70, and a case 35.

[0016] In this application, the direction parallel to the central axis of the upper-stage shaft 40 is referred to as the axial direction. The direction approaching and moving away from the central axis of the upper-stage shaft 40 is referred to as the radial direction. The direction around the central axis of the upper-stage shaft 40 is referred to as the circumferential direction. The central axes of the worm wheel 32, the lower-stage shaft 46, and the case 35 coincide with the central axis of the upper-stage shaft 40. The central axis of the upper-stage shaft 40 is parallel to the up-down direction.

[0017] The worm 31 is connected to an electric operating mechanism (not shown). The worm wheel 32 meshes with the worm 31. The worm wheel 32 reduces the rotation speed of the worm 31.

[0018] The upper shaft 40 is disposed in the center of the worm wheel 32. The upper shaft 40 and the worm wheel 32 are connected via a key 33 in the circumferential direction.

[0019] The lower-stage shaft 46 is disposed below the upper-stage shaft 40. A lower end portion 47 of the lower-stage shaft 46 is connected to the upper end portion of the drive shaft 14. An upper end portion 48 of the lower-stage shaft 46 has a larger diameter than a central portion of the lower-stage shaft 46 in the axial direction.

[0020] The lower end 45 of the upper shaft 40 is detachable from the upper end 48 of the lower shaft 46 . FIG. 4 is a perspective view of the upper-stage shaft. FIG. 5 is a cross-sectional view taken along line VV in FIG. 3. In a cross section perpendicular to the axial direction, the outer shape of the lower end portion 45 of the upper-stage shaft 40 is rectangular. In a cross section perpendicular to the axial direction, the upper end portion 48 of the lower-stage shaft 46 has a rectangular hole 49 in the center. The lower end portion 45 of the upper-stage shaft 40 is inserted into the hole 49 in the upper end portion 48 of the lower-stage shaft 46. This connects the upper-stage shaft 40 and the lower-stage shaft 46 in the circumferential direction. The upper-stage shaft 40 and the lower-stage shaft 46 are detachable in the axial direction.

[0021] Power generated by an electric operation mechanism (not shown) is transmitted to the drive shaft 14 shown in Fig. 1 via the worm 31, the worm wheel 32, the upper shaft 40, and the lower shaft 46 of the gear mechanism 30 shown in Fig. 3. The power is introduced from the drive shaft 14 through the power introduction section 15 to the change-over switch 12 and the tap selector 11.

[0022] As shown in Fig. 4, the upper-stage shaft 40 has a power restricting portion 44. The power restricting portion 44 restricts the transmission of power exceeding a predetermined value. The power restricting portion 44 is disposed between the axial center portion and the lower end portion 45 of the upper-stage shaft 40. The power restricting portion 44 has a smaller diameter than the axial center portion of the upper-stage shaft 40. The cross-sectional area of ​​the power restricting portion 44 in a cross section perpendicular to the axial direction is smaller than the cross-sectional areas of other portions of the upper-stage shaft 40 and the lower-stage shaft 46.

[0023] When abnormal torque exceeding a predetermined value occurs in the changeover switch 12 and the tap selector 11, the power regulating portion 44 of the upper shaft 40 breaks (ruptures). This suppresses the load of abnormal torque on the changeover switch 12 and the tap selector 11, and protects the changeover switch 12 and the tap selector 11.

[0024] The tap display mechanism 70 is disposed on the upper part of the gear mechanism 30, as shown in FIG. 3. The tap display mechanism 70 displays the tap selected by the tap selector 11. As shown in FIG. 4, an engagement groove 41 is formed at the upper end of the upper-stage shaft 40. As shown in FIG. 3, the central axis of the tap display mechanism 70 engages with the engagement groove 41 of the upper-stage shaft 40. The tap display mechanism 70 operates in conjunction with the rotation of the upper-stage shaft 40.

[0025] As shown in FIG. 3, the case 35 covers the entire gear mechanism 30. The case 35 has, from top to bottom, a first chamber 36, a second chamber 37, and a third chamber 38. The diameter of the case 35 in a cross section perpendicular to the axial direction decreases from the first chamber 36 to the third chamber 38. The first chamber 36 houses the tap display mechanism 70. The second chamber 37 houses the worm wheel 32 and the upper half of the upper shaft 40. The third chamber 38 houses the lower half of the upper shaft 40 and the upper half of the lower shaft 46. The case 35 has a worm chamber 39 adjacent to the second chamber 37. The worm chamber 39 houses the worm 31.

[0026] The upper opening of the first chamber 36 is closed by a case lid 72. The case lid 72 is fixed to the case 35 by a first fixing screw 71. Between the first chamber 36 and the second chamber 37, the base plate 52 and the support plate 53 are arranged overlapping in the vertical direction. The base plate 52 and the support plate 53 are fixed to the case 35 by a second fixing screw 74.

[0027] The upper-stage shaft 40 is rotatably supported by a plurality of bearings 51, 56. In the embodiment, the upper-stage shaft 40 is supported by a pair of bearings (a first bearing 51 and a second bearing 56). The first bearing 51 supports the upper end of the upper-stage shaft 40. The second bearing 56 supports the upper side of the power regulating unit 44 of the upper-stage shaft 40. Each of the bearings 51, 56 is a rolling bearing such as a ball bearing or a roller bearing. Each of the bearings 51, 56 may be a sliding bearing.

[0028] The inner circumference of the inner ring of the first bearing 51 abuts against the outer circumference of the upper shaft 40. The outer circumference of the outer ring of the first bearing 51 abuts against the inner circumference of the central hole of the support plate 53. This supports the first bearing 51 in the radial direction. The lower end of the inner ring of the first bearing 51 abuts against a retaining ring (retaining ring) 54 fixed to the outer circumference of the upper shaft 40. As shown in FIG. 4, a groove 42 for fixing the retaining ring 54 is formed on the outer circumference of the upper shaft 40. As shown in FIG. 3, the upper end of the outer ring of the first bearing 51 abuts against the base plate 52. This supports the first bearing 51 in the axial direction.

[0029] The inner periphery of the inner ring of the second bearing 56 abuts against the outer periphery of the upper shaft 40. The outer periphery of the outer ring of the second bearing 56 abuts against the inner periphery of the third chamber 38. This supports the second bearing 56 in the radial direction. The upper end of the inner ring of the second bearing 56 abuts against the worm wheel 32. The lower end of the outer ring of the second bearing 56 abuts against a retaining ring 57 fixed to the inner periphery of the third chamber 38. This supports the second bearing 56 in the axial direction.

[0030] In this manner, the pair of bearings 51, 56 are supported in the radial and axial directions. The upper shaft 40 is supported at both ends by the pair of bearings 51, 56. This allows the upper shaft 40 to rotate stably with low torque.

[0031] The lower-stage shaft 46 is rotatably supported by a plurality of bearings 61, 66. In the embodiment, the lower-stage shaft 46 is supported by a pair of bearings (a third bearing 61 and a fourth bearing 66). The third bearing 61 supports the lower part of the upper end of the lower-stage shaft 46. The fourth bearing 66 supports the upper part of the lower end of the lower-stage shaft 46. Each of the bearings 61, 66 is a rolling bearing such as a ball bearing or a roller bearing. Each of the bearings 61, 66 may be a sliding bearing.

[0032] The inner periphery of the inner ring of the third bearing 61 abuts against the outer periphery of the lower shaft 46. The outer periphery of the outer ring of the third bearing 61 abuts against the inner periphery of the third chamber 38. This supports the third bearing 61 in the radial direction. The upper end of the inner ring of the third bearing 61 abuts against the upper end 48 of the lower shaft 46. A protruding portion 62 that protrudes toward the lower shaft 46 is formed on the inner periphery of the third chamber 38. The lower end of the outer ring of the third bearing 61 abuts against the upper surface of the protruding portion 62 of the third chamber 38. This supports the third bearing 61 in the axial direction.

[0033] The inner periphery of the inner ring of the fourth bearing 66 abuts against the outer periphery of the lower end portion 47 of the lower shaft 46. The outer periphery of the outer ring of the fourth bearing 66 abuts against the inner periphery of the third chamber 38. This supports the fourth bearing 66 in the radial direction. The lower end of the inner ring of the fourth bearing 66 abuts against a retaining ring 67 fixed to the outer periphery of the lower shaft 46. The upper end of the outer ring of the fourth bearing 66 abuts against the lower surface of the protruding portion 62 of the third chamber 38. This supports the fourth bearing 66 in the axial direction.

[0034] In this manner, the pair of bearings 61, 66 are supported in the radial and axial directions. The lower shaft 46 is supported at both ends by the pair of bearings 61, 66. This allows the lower shaft 46 to rotate stably with low torque.

[0035] The gear mechanism 30 has seal parts 63, 64. The seal parts 63, 64 seal the first insulating oil 6 between the case 35 and the lower shaft 46 in the axial direction of the lower shaft 46. An oil seal, a Y packing, a U packing, or the like is disposed between the protruding part 62 of the third chamber 38 and the lower shaft 46 to form the seal parts 63, 64. By employing the Y packing or the U packing, the parts cost of the gear mechanism 30 is suppressed and the gear mechanism 30 is made compact. The seal parts 63, 64 have a first seal part 63 and a second seal part 64 that are disposed side by side in the axial direction. The pair of seal parts 63, 64 improves the sealing performance.

[0036] A restoration method for the case where the power restricting portion 44 of the upper shaft 40 is broken will be described with reference to FIG. In the first half of the work, the broken upper shaft 40 is removed. Specifically, the first fixing screw 71 is removed, and the case lid 72 is removed. This opens the top of the first chamber 36. The second fixing screw 74 is removed from the case 35. The tap display mechanism 70, the base plate 52, and the support plate 53 are removed. The first bearing 51 is removed from the upper shaft 40.

[0037] The worm wheel 32 is moved upward while rotating the worm 31, and the worm wheel 32 is removed. The upper half of the upper shaft 40 above the broken power regulating portion 44 is taken out. The lower half of the upper shaft 40 below the broken power regulating portion 44 is taken out through the inside of the second bearing 56. The lower end portion 45 of the upper shaft 40 is detachable from the upper end portion 48 of the lower shaft 46. The upper shaft 40 can be detached from the lower shaft 46 simply by lifting the lower half of the upper shaft 40.

[0038] It may be difficult to remove the lower half of the upper shaft 40 through the inside of the second bearing 56. In this case, the second bearing 56 (and the retaining ring 57) is removed from the case 35, and then the lower half of the upper shaft 40 is removed.

[0039] In the latter half of the work, a new upper shaft 40 is attached. Specifically, the upper shaft 40 is inserted inside the second bearing 56. The lower end 45 of the upper shaft 40 is inserted into a hole 49 in the upper end 48 of the lower shaft 46. The upper shaft 40 can be attached to the lower shaft 46 simply by lowering the upper shaft 40. Thereafter, the gear mechanism 30 is assembled in the reverse order of the first half of the work. With the above, the restoration work for the upper shaft 40 is completed.

[0040] In this way, the restoration work is completed by only replacing the upper shaft 40, and there is no need to replace the lower shaft 46. In order to prevent leakage of the first insulating oil 6 accompanying the replacement work of the lower shaft 46, there is no need to drain the first insulating oil 6. As described above, the seal portions 63, 64 seal the first insulating oil 6 in the axial direction of the lower shaft 46 between the case 35 and the lower shaft 46. Leakage of the first insulating oil 6 accompanying the replacement work of the upper shaft 40 is suppressed. This reduces the maintenance man-hours for the on-load tap changer 10.

[0041] As described above in detail, the on-load tap changer 10 of the embodiment has the lower shaft 46, the upper shaft 40, and the power regulating unit 44. The upper end portion 48 of the lower shaft 46 is disposed outside the first insulating oil 6. The upper shaft 40 is detachable from the upper end portion 48 of the lower shaft 46, and is disposed outside the first insulating oil 6. The power regulating unit 44 is provided on the upper shaft 40, and regulates the transmission of power exceeding a predetermined value.

[0042] A power regulating unit 44 is provided on the upper shaft 40, and the upper shaft 40 is detachable from an upper end 48 of the lower shaft 46. As a result, when the power regulating unit 44 is activated, recovery work can be completed by replacing only the upper shaft 40. The upper end 48 of the lower shaft 46 and the upper shaft 40 are disposed outside the first insulating oil 6. As a result, replacement work of the upper shaft 40 can be performed in the air. Replacement of the lower shaft 46 is not required, and there is no need to drain the first insulating oil 6. Therefore, the maintenance man-hours for the on-load tap changer 10 can be reduced.

[0043] The on-load tap changer 10 further includes an oil tank 20, a flange 27, and a gear mechanism 30. The oil tank 20 accommodates the diverter switch 12. The flange 27 extends outside the oil tank 20. The gear mechanism 30 is fixed to the flange 27 and rotatably supports the lower shaft 46 and the upper shaft 40.

[0044] The change-over switch 12 is accommodated in the oil tank 20. This allows the change-over switch 12 to be removed simply by draining the second insulating oil 21 in the oil tank 20, without draining the first insulating oil 6 in the tank 5. The gear mechanism 30 is fixed to the flange 27, and is not fixed to the oil tank lid 25. This allows the change-over switch 12 to be removed from the oil tank 20 by removing the oil tank lid 25, without removing the gear mechanism 30. Therefore, the number of maintenance man-hours for the change-over switch 12 can be reduced.

[0045] The on-load tap changer 10 has seal portions 63, 64. The seal portions 63, 64 seal the first insulating oil 6 between the lower shaft 46 and the case 35 of the gear mechanism 30 in the axial direction of the lower shaft 46. This allows the replacement work of the upper shaft 40 to be carried out in the air without being affected by the first insulating oil 6. Therefore, the number of maintenance steps for the on-load tap changer 10 can be reduced.

[0046] The seal portions 63, 64 include a first seal portion 63 and a second seal portion 64 that are arranged side by side in the axial direction. This improves the sealing performance of the seal portions 63 and 64.

[0047] The upper shaft 40 is rotatably supported by a plurality of bearings 51 and 56. The lower shaft 46 is rotatably supported by a plurality of bearings 61 and 66. This allows the upper shaft 40 and the lower shaft 46 to rotate stably with low torque.

[0048] According to at least one of the embodiments described above, the upper shaft 40 has a power regulating unit 44, is detachable from the upper end portion 48 of the lower shaft 46, and is disposed outside the first insulating oil 6. This makes it possible to reduce the number of maintenance steps required for the on-load tap changer 10.

[0049] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0050] 6...first insulating oil, 10...on-load tap changer, 12...changer switch, 20...oil tank, 21...second insulating oil, 27...flange, 30...gear mechanism, 35...case, 40...upper shaft, 44...power regulating portion, 46...lower shaft, 48...upper end portion, 51...first bearing, 56...second bearing, 61...third bearing, 63...first seal portion, 64...second seal portion, 66...fourth bearing.

Claims

1. A lower shaft having an upper end disposed outside the insulating oil; an upper shaft that is detachably attached to the upper end of the lower shaft and is disposed outside the insulating oil; a power regulating portion provided on the upper shaft and configured to regulate transmission of power exceeding a predetermined value; a gear case for a gear mechanism that accommodates the lower shaft and the upper shaft, The gear case of the gear mechanism is integrally formed, The upper stage shaft is detachable from the gear case of the gear mechanism. On-load tap changer.

2. an oil tank for accommodating a change-over switch; a flange extending outwardly of the oil tank; The gear mechanism is fixed to the flange and rotatably supports the lower stage shaft and the upper stage shaft.

2. An on-load tap changer according to claim 1.

3. a seal portion that seals the insulating oil in an axial direction of the lower stage shaft between the lower stage shaft and a gear case of the gear mechanism, 3. An on-load tap changer according to claim 2.

4. The seal portion has a first seal portion and a second seal portion arranged side by side in the axial direction. An on-load tap changer according to claim 3.

5. The upper stage shaft is rotatably supported by a plurality of bearings, The lower shaft is rotatably supported by a plurality of bearings. An on-load tap changer according to any one of claims 1 to 4.

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