Changeover switch for on-load tap changer

Abstract

To provide a changeover switch for an on-load tap changer that can be reduced in size.SOLUTION: A changeover switch for an on-load tap changer according to an aspect 1 of an embodiment has a shaft, a valve, a cam member, and a current-limiting resistor. The cam member is arranged between the shaft and the valve in a radial direction of the shaft. The cam member rotates in a circumferential direction of the shaft to drive the valve. The current-limiting resistor is arranged side by side with the cam member in an axial direction of the shaft. The cam member has a cam ring, a hub, and a plurality of blade plates. The cam ring is arranged on the outside of the radial direction. The hub is arranged on the inside of the radial direction. The blade plates are connected to the cam ring and the hub and intersect the axial direction at an angle other than perpendicularity. The plurality of blade plates are arranged with gaps in the circumferential direction.SELECTED DRAWING: Figure 10

Description

[Technical Field]

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

[0002] An on-load tap changer is a device that changes taps while the transformer is in operation (on load). Generally, an on-load tap changer has a tap selector and a diverter switch. The tap selector selects the tap to operate in the transformer tap winding. The diverter switch switches the circuit to the selected tap. Miniaturization of the diverter switch is required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2635867 [Patent Document 2] Patent No. 4660490 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a diverter switch for an on-load tap changer that can be made compact. [Means for solving the problem]

[0005] The changeover switch of the on-load tap changer of embodiment 1 has a shaft, a valve, a cam member, and a current-limiting resistor. The valve connects and disconnects between the tap terminal and the neutral point. The cam member is disposed between the shaft and the valve in the radial direction of the shaft. The cam member rotates in the circumferential direction of the shaft to drive the valve. The current-limiting resistor is disposed alongside the cam member in the axial direction of the shaft. The current-limiting resistor is connected between the tap terminal and the neutral point. The cam member has a cam ring, a hub, and multiple vanes. The cam ring is disposed on the radial outside. The hub is disposed on the radial inside. The vanes are connected to the cam ring and the hub and intersect with the axial direction at an angle other than perpendicular. The multiple vanes are disposed with gaps in the circumferential direction.

[0006] A diverter switch for an on-load tap changer of aspect 2 is based on the diverter switch for an on-load tap changer of aspect 1. The valve has a valve body and a lever. The valve body is arranged along the axial direction. The lever is formed in an L-shape and is rotatable around a rotation axis along the circumferential direction. The rotation axis is arranged radially inside the valve body. The lever has a first arm and a second arm. The first arm extends radially outward from the rotation axis and has a tip connected to the valve body. The second arm extends along the axial direction from the rotation axis and has a cam follower at its tip that abuts against a cam ring.

[0007] A changing switch for an on-load tap changer according to a third aspect is based on the changing switch for an on-load tap changer according to the first or second aspect. The current-limiting resistor is supported on a mounting plate disposed between the cam member and the current-limiting resistor. A plurality of through holes are formed in the mounting plate.

[0008] A diverter switch of an on-load tap changer of aspect 4 is based on the diverter switch of an on-load tap changer according to aspect 3. The plurality of through holes are formed at positions that overlap with the current-limiting resistors in the axial direction.

[0009] A diverter switch for an on-load tap changer according to a fifth aspect is based on the diverter switch for an on-load tap changer according to the third or fourth aspect. The valve is mounted on a unit base. The cam member is disposed radially inside the unit base. An earth shield is disposed axially on the opposite side of the mounting plate with the current-limiting resistor between them, covering the current-limiting resistor. The plurality of through holes are formed separately on the radial inside and outside of the unit base. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of an on-load tap changer according to an embodiment. [Figure 2] 3 is a circuit diagram for one phase of the changeover switch according to the embodiment. FIG. [Figure 3] 4 is a timing chart of the switching operation of a changeover switch. [Figure 4] FIG. 1 is a first exploded perspective view of a changeover switch according to an embodiment. [Figure 5] FIG. 4 is an explanatory diagram of the connection state of the tap terminal and the neutral terminal. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 4 is a side cross-sectional view of the first main valve and the main valve cam member. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a changeover switch for 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 1 according to an embodiment. In FIG. 1, the front half of the cylindrical container 10a has been removed to show the interior of the cylindrical container 10a. The on-load tap changer 1 is a device that adjusts voltage by changing the turns ratio (transformation ratio) of a transformer while the transformer is in operation. The on-load tap changer 1 includes a tap selector 2, a drive mechanism 5, and a diverter switch 10.

[0012] The tap selector 2 performs a selection operation to select a tap to operate in the transformer tap winding. The drive mechanism 5 drives the tap selector 2 by a driving force transmitted from an electric operating device (not shown) via a drive shaft 6. The diverter switch 10 performs a switching operation to switch a circuit to a selected tap. The diverter switch 10 is disposed inside a cylindrical container 10a.

[0013] The changeover switch 10 of the embodiment will be described in detail. FIG. 2 is a circuit diagram of a diverter switch 10 according to an embodiment, showing one phase of a three-phase AC current. The following describes the configuration of one phase of the diverter switch 10 unless otherwise specified. The diverter switch 10 switches circuits between a first tap terminal T1 and a second tap terminal T2. The diverter switch 10 has a first circuit C1 and a second circuit C2. The first circuit C1 connects between a neutral terminal 18 and the first tap terminal T1. The second circuit C2 connects between the neutral terminal 18 and the second tap terminal T2.

[0014] The changeover switch 10 has a first energizing switch SM1 and a second energizing switch SM2. First ends of the first energizing switch SM1 and the second energizing switch SM2 are connected to the neutral terminal 18. A second end of the first energizing switch SM1 is connected to a first tap terminal T1. A second end of the second energizing switch SM2 is connected to a second tap terminal T2.

[0015] The diverter switch 10 has a plurality of valves VM1, VM2, VR1, and VR2. The valves are vacuum circuit breakers that use a vacuum as an insulating and arc-extinguishing medium. The plurality of valves include a first main valve VM1, a second main valve VM2, a first resistance valve VR1, and a second resistance valve VR2.

[0016] A first end of the first main valve VM1 and a first end of the second main valve VM2 are connected to the neutral terminal 18. A second end of the first main valve VM1 is connected to a first end of the first resistance valve VR1. The first main valve VM1 and the first resistance valve VR1 are connected in series. A second end of the second main valve VM2 is connected to a first end of the second resistance valve VR2. The second main valve VM2 and the second resistance valve VR2 are connected in series.

[0017] The diverter switch 10 has a first current-limiting resistor R1 and a second current-limiting resistor R2. The first current-limiting resistor R1 and the second current-limiting resistor R2 limit the current during tap changing. The first current-limiting resistor R1 is connected in parallel with the first main valve VM1 between the neutral terminal 18 and the first resistance valve VR1. The second current-limiting resistor R2 is connected in parallel with the second main valve VM2 between the neutral terminal 18 and the second resistance valve VR2. That is, a first end of the first current-limiting resistor R1 and a first end of the second current-limiting resistor R2 are connected to the neutral terminal 18. A second end of the first current-limiting resistor R1 is connected to a first end of the first resistance valve VR1. A second end of the second current-limiting resistor R2 is connected to a first end of the second resistance valve VR2.

[0018] The diverter switch 10 has a first isolation switch SD1 and a second isolation switch SD2. A first end of the first isolation switch SD1 is connected to a second end of the first resistance valve VR1. A first end of the second isolation switch SD2 is connected to a second end of the second resistance valve VR2. A second end of the first isolation switch SD1 is connected to a first tap terminal T1. A second end of the second isolation switch SD2 is connected to a second tap terminal T2.

[0019] The changeover switch 10 has a first potential switch SV1 and a second potential switch SV2. A first end of the first potential switch SV1 is connected to the neutral terminal 18 via a first current-limiting resistor R1. A first end of the second potential switch SV2 is connected to the neutral terminal 18 via a second current-limiting resistor R2. A second end of the first potential switch SV1 is connected to a movable part of the first energizing switch SM1 and a movable part of the first separation switch SD1. A second end of the second potential switch SV2 is connected to a movable part of the second energizing switch SM2 and a movable part of the second separation switch SD2.

[0020] The first circuit C1 includes the first current-limiting resistor R1, first main valve VM1, and first resistance valve VR1, as well as a first switch unit S1. The first switch unit S1 includes the first energization switch SM1, first separation switch SD1, and first potential switch SV1. The first separation switch SD1 opens when the first circuit C1 is de-energized, separating the first circuit C1 from the first tap terminal T1. When the first energization switch SM1 and the first separation switch SD1 are open, the first potential switch SV1 connects the movable parts of the first energization switch SM1 and the first separation switch SD1 to the neutral terminal 18.

[0021] The second circuit C2 includes the second current-limiting resistor R2, the second main valve VM2, and the second resistance valve VR2, as well as the second switch unit S2. The second switch unit S2 includes the second energization switch SM2, the second separation switch SD2, and the second potential switch SV2. The second separation switch SD2 opens when the second circuit C2 is de-energized, separating the second circuit C2 from the second tap terminal T2. The second potential switch SV2 connects the movable parts of the second energization switch SM2 and the second separation switch SD2 to the neutral terminal 18 when the second energization switch SM2 and the second separation switch SD2 are open.

[0022] The switching operation (sequence) of the diverter switch 10 will now be described. Figure 3 is a timing chart of the switching operation of the diverter switch 10. Figure 3 is an explanatory diagram of the change in the current flow state during the switching operation from the first tap terminal T1 to the second tap terminal T2. In each chart in Figure 3, the upper side represents the closed (ON) state, and the lower side represents the open (OFF) state.

[0023] At time A, the first energizing switch SM1, first main valve VM1, first resistance valve VR1, and first separation switch SD1 of the first circuit C1 are closed. Meanwhile, the second energizing switch SM2, second main valve VM2, and second separation switch SD2 of the second circuit C2 are open, and the second resistance valve VR2 is closed. As a result, at time A, current is applied to the first tap terminal T1 via the first energizing switch SM1 of the first circuit C1. Note that the first potential switch SV1 is open, and the second potential switch SV2 is closed. With the second potential switch SV2 closed, the movable parts of the second energizing switch SM2 and the second separation switch SD2, which are open, are connected to the neutral terminal 18.

[0024] From time A to time B, the first energization switch SM1 of the first circuit C1 opens. Meanwhile, the second resistance valve VR2 of the second circuit C2 opens and the second separation switch SD2 closes. As a result, at time B, current is applied to the first tap terminal T1 via the first main valve VM1, first resistance valve VR1, and first separation switch SD1 of the first circuit C1. Furthermore, from time A to time B, the second potential switch SV2 opens.

[0025] From time B to time C, the first main valve VM1 of the first circuit C1 opens. Meanwhile, the second resistance valve VR2 of the second circuit C2 closes. As a result, at time C, current flows through the first tap terminal T1 via the first current-limiting resistor R1, the first resistance valve VR1, and the first separation switch SD1 of the first circuit C1. Also, current flows through the second current-limiting resistor R2, the second resistance valve VR2, and the second separation switch SD2 of the second circuit C2 to the second tap terminal T2.

[0026] From time C to time D, the first resistance valve VR1 of the first circuit C1 opens. As a result, at time D, current is passed through the second tap terminal T2 via the second current-limiting resistor R2, the second resistance valve VR2, and the second separation switch SD2 of the second circuit C2.

[0027] From time D to time E, the first separation switch SD1 of the first circuit C1 is opened. Meanwhile, the second main valve VM2 and the second energizing switch SM2 of the second circuit C2 are closed. As a result, at time E, electricity is applied to the second tap terminal T2 via the second energizing switch SM2 of the second circuit C2. Note that from time D to time E, the first potential switch SV1 is closed. As a result, the movable part of the open first energizing switch SM1 and the movable part of the first separation switch SD1 are connected to the neutral terminal 18.

[0028] This completes the switching from the first tap terminal T1 to the second tap terminal T2. Switching from the second tap terminal T2 to the first tap terminal T1 is the reverse of the above operation.

[0029] Fig. 4 is a first exploded perspective view of the diverter switch 10 of the embodiment. Fig. 5 is an explanatory diagram of the connection state of the tap terminals T1, T2 and the neutral terminal 18. In Fig. 5, the unit base 16 of the switching unit 15 on the front side is not shown. The diverter switch 10 shown in Fig. 4 is placed inside a cylindrical container 10a (see Fig. 1). The cylindrical container 10a is filled with insulating gas or insulating oil as an insulating fluid. In addition to SF6 gas, naturally occurring gases such as N2 gas and CO2 gas can also be used as the insulating gas.

[0030] In this application, the Z direction, R direction, and θ direction of the cylindrical coordinate system are defined as follows: The Z direction is the axial direction of the central axis of the shaft 61 disposed at the center of the change-over switch 10. For example, the Z direction is the vertical direction, and the +Z direction is the upward direction. The R direction is the radial direction of the shaft 61. The +R direction is the radially outward direction (direction away from the central axis). The θ direction is the circumferential direction of the central axis of the shaft 61. The +θ direction is the rotation direction of a right-handed screw advancing in the +Z direction. For example, the R direction and the θ direction are horizontal directions.

[0031] The changeover switch 10 has a pair of mounting plates 12, 13, that is, a first mounting plate 12 and a second mounting plate 13, and a support 14. The pair of mounting plates 12, 13 and the support 14 are formed of a conductive metal material and are connected to a neutral terminal 18 (see FIG. 5). The neutral terminal 18 is connected to the tap selector 2 (see FIG. 1). As shown in FIG. 4, the pair of mounting plates 12, 13 are formed in a substantially disk shape and are arranged parallel to each other and spaced apart in the Z direction. The first mounting plate 12 is arranged in the +Z direction, and the second mounting plate 13 is arranged in the -Z direction. The support 14 is arranged between the pair of mounting plates 12, 13 and on the -Z direction of the second mounting plate 13.

[0032] The change-over switch 10 has a current-limiting resistor R0, which is the first current-limiting resistor R1 or the second current-limiting resistor R2 described above. The current-limiting resistor R0 is fixed to the surface in the +Z direction of the first mounting plate 12. In order to promote heat dissipation from the current-limiting resistor R0, the first mounting plate 12 is made of an aluminum alloy or the like with high thermal conductivity.

[0033] The diverter switch 10 has an earth shield 11. The earth shield 11 is placed at the end of the diverter switch 10 in the +Z direction and covers the current-limiting resistor R0. The cover 1a of the on-load tap changer 1 shown in FIG. 1 is grounded. The earth shield 11 reduces the electric field between the cover 1a and the diverter switch 10, ensuring insulation between them. To promote heat dissipation from the current-limiting resistor R0, the earth shield 11 is made of an aluminum alloy or the like with high thermal conductivity.

[0034] 4, the diverter switch 10 has a switching unit 15 and a cam unit 60. The switching unit 15 and the cam unit 60 are disposed inside the pair of mounting plates 12, 13 and are supported by both of them.

[0035] The switching unit 15 has the components of the first circuit C1 excluding the first current-limiting resistor R1, the components of the second circuit C2 excluding the second current-limiting resistor R2, and a unit base 16 that supports them. The switching unit 15 is arranged in the +R direction of the cam unit 60. A switching unit 15 is formed for each phase of the three-phase AC. The three-phase switching units 15 are arranged side by side in the θ direction.

[0036] 5, the first switch section S1 of the switching unit 15 is connected to the first tap terminal T1 via the bus bar 17. The second switch section S2 of the switching unit 15 is connected to the second tap terminal T2 via the bus bar 17.

[0037] The cam unit 60 is arranged along the central axis of the change-over switch 10. The cam unit 60 performs the switching operation of the three-phase switching unit 15. The cam unit 60 has a shaft 61, a main valve cam member (cam member) 70, a composite cam 65, and an energization switch cam 68. The main valve cam member 70 is arranged in the +Z direction of the shaft 61 and drives the main valves VM1 and VM2. The composite cam 65 is arranged in the center of the shaft 61 in the Z direction. The composite cam 65 is formed by integrating a resistance valve cam and a separation switch cam. The resistance valve cam drives the resistance valves VR1 and VR2, and the separation switch cam drives the separation switches SD1 and SD2. The energization switch cam 68 is arranged in the -Z direction of the shaft 61 and drives the energization switches SM1 and SM2.

[0038] The changeover switch 10 has an energy storage mechanism 20. The energy storage mechanism 20 is disposed in the −Z direction of the second mounting plate 13. Fig. 6 is a first perspective view from above of the energy accumulating mechanism 20. Fig. 7 is a second perspective view from below of the energy accumulating mechanism 20. The energy accumulating mechanism 20 has an eccentric arm 22, a drive arm 24, an energy accumulating spring 20s, a switching arm 26, a Geneva driver 30, and a Geneva 34.

[0039] The charging operation of the charging mechanism 20 will now be described. The drive mechanism 5 (see FIG. 1) performs the charging operation of the charging mechanism 20 in parallel with the selection operation of the tap selector 2. The rotation of the drive shaft 6 of the drive mechanism 5 causes the eccentric arm 22 to rotate from the state shown in FIG. 7. The tip of the eccentric arm 22 presses one end of the drive arm 24. The other end of the drive arm 24 presses the operating portion 27 formed on the switching arm 26.

[0040] The switching arm 26 is rotatable around the shaft 61. The operating unit 27 is disposed away from the shaft 61. One end of the energy storage spring 20s is hingedly connected to the operating unit 27. The other end of the energy storage spring 20s is hingedly connected to the frame. A plane including the rotation axis of the other end of the energy storage spring 20s and the central axis of the shaft 61 is defined as a neutral plane.

[0041] When the operating unit 27 is pushed and approaches the neutral plane, the energy storage spring 20s is compressed and the spring force is stored. When the operating unit 27 passes the neutral plane, the spring force stored in the energy storage spring 20s is released. Due to the release of the spring force of the energy storage spring 20s, the switching arm 26 together with the operating unit 27 rotates from the state shown in FIG. 6.

[0042] The pressing portion 28 of the switching arm 26 presses one end of the Geneva driver 30. A roller 31 arranged at the other end of the Geneva driver 30 enters a slot 35 of the Geneva 34. Rotation of the Geneva driver 30 rotates the Geneva 34. This rotates the shaft 61 fixed to the Geneva 34. The main valve cam member 70 fixed to the shaft 61 rotates together with the shaft 61.

[0043] As a result of the above, the energy accumulating mechanism 20 rotates the cam unit 60 including the shaft 61 and the main valve cam member 70 by a predetermined angle. As a result, the energy accumulating mechanism 20 instantaneously performs the switching operation of the changeover switch 10. When the drive shaft 6 (see FIG. 1) of the drive mechanism 5 continues to rotate in the same direction or rotates in the opposite direction, the energy accumulating mechanism 20 performs an energy accumulating operation symmetrical with respect to the neutral plane. As a result, the energy accumulating mechanism 20 instantaneously performs the switching operation of the changeover switch 10 in the opposite direction.

[0044] 8 is a side cross-sectional view of the first main valve VM1 and the main valve cam member 70. The first main valve VM1 has a valve body Vm, a lever 48, and a biasing member Vs. The valve body Vm is disposed in the +R direction of the unit base 16. The valve body Vm has a case Vc, a fixed electrode Va, and a movable electrode Vb. The case Vc is formed in a cylindrical shape. The central axis of the case Vc is disposed along the Z direction. The interior of the case Vc is maintained in a vacuum. The fixed electrode Va and the movable electrode Vb are housed inside the case Vc. The position of the fixed electrode Va is fixed. The movable electrode Vb is disposed in the -Z direction of the fixed electrode Va and is movable in the Z direction.

[0045] The lever 48 is formed in an L-shape. The lever 48 is rotatable around a rotation axis 48x. The rotation axis 48x extends in the θ direction (tangential to the θ direction). The rotation axis 48x is disposed in the −R direction of the valve body Vm. The lever 48 has a first arm 48a and a second arm 48b. The first arm 48a extends in the +R direction from the rotation axis 48x. The tip of the first arm 48a is connected to the movable electrode Vb of the valve body Vm. The second arm 48b extends in the +Z direction from the rotation axis 48x. A roller 49 (cam follower) is disposed at the tip of the second arm 48b. The roller 49 is exposed in the −R direction of the unit base 16. The roller 49 abuts against a cam ring 72 of the main valve cam member 70.

[0046] The biasing member Vs biases the movable electrode Vb in a direction in which the movable electrode Vb abuts against the fixed electrode Va (in a direction in which the first main valve VM1 closes). When the cam ring 72 of the main valve cam member 70 presses the roller 49 in the +R direction, the lever 48 rotates around the rotation axis 48x. This separates the movable electrode Vb from the fixed electrode Va, opening the first main valve VM1. The second main valve VM2 is configured similarly to the first main valve VM1.

[0047] Because the lever 48 is formed in an L-shape, the main valves VM1, VM2 are compact in the R direction. The main valves VM1, VM2 are arranged near the end of the first mounting plate 12 in the +R direction. The main valve cam member 70 is arranged on the -R side of the main valves VM1, VM2. This allows the main valve cam member 70 to be formed with a large diameter.

[0048] 9 is a perspective view of the main valve cam member 70. The main valve cam member 70 is integrally formed from a resin material or the like. The main valve cam member 70 has a cam ring 72, a hub 73, and vanes 75.

[0049] The cam ring 72 is disposed in the +R direction of the main valve cam member 70. A cam surface is formed on the outer periphery of the cam ring 72. The cam surface abuts against the rollers 49 (see FIG. 8), thereby driving the main valves VM1 and VM2. The hub 73 is disposed on the −R side of the main valve cam member 70. The hub 73 is fixed in the θ direction relative to the shaft 61 (see FIG. 8).

[0050] The +R end of the vane plate 75 is connected to the cam ring 72, and the -R end is connected to the hub 73. As described above, the cam ring 72 of the main valve cam member 70 presses the roller 49 (see FIG. 8) of the first main valve VM1 in the +R direction. At this time, the cam ring 72 receives a reaction force in the -R direction, but not in the Z direction. The vane plate 75 is required to have compression rigidity in the R direction, but not bending rigidity in the Z direction. Therefore, the vane plate 75 can be formed into a thin plate.

[0051] The surfaces of the vanes 75 intersect with the Z direction at an angle other than perpendicular. When the main valve cam member 70 rotates in the θ direction, the insulating fluid present around the vanes 75 is pushed out in the Z direction from the surfaces of the vanes 75 and drawn in in the Z direction toward the surfaces of the vanes 75. This causes the insulating fluid to flow in the Z direction of the main valve cam member 70.

[0052] A plurality of vanes 75 are arranged with gaps in the θ direction. Between adjacent vanes 75 in the θ direction, a through-hole is formed that penetrates the main valve cam member 70 in the Z direction. As described above, when the main valve cam member 70 rotates in the θ direction, the insulating fluid flows in the Z direction. The insulating fluid passes through the through-holes in the main valve cam member 70 and flows in the Z direction across the main valve cam member 70. Furthermore, because adjacent vanes 75 are spaced apart in the θ direction, they do not overlap in the Z direction. This facilitates the integral molding of the main valve cam member 70.

[0053] Fig. 10 is a second exploded perspective view of the changeover switch 10. In Fig. 10, the three-phase switching unit 15 (see Fig. 4) is omitted. In addition to mounting holes 15h for the unit base 16 of the switching unit 15, cooling holes (through holes) 50 are formed in the first mounting plate 12. The mounting holes 15h and the cooling holes 50 penetrate the first mounting plate 12 in the Z direction. 11 is a bottom view of the first mounting plate 12. The mounting holes 15h of the unit base 16 are arranged at the center and both ends of the unit base 16 in the θ direction.

[0054] One current-limiting resistor R0 consists of three resistors Rc and Rd. The three resistors Rc and Rd are arranged radially at 120° intervals. The three resistors Rc and Rd include one inner resistor Rc and two outer resistors Rd. The inner resistor Rc is arranged along the R direction. The outer resistors Rd are arranged in the +R direction from the inner resistor Rc.

[0055] The cooling holes 50 include inner cooling holes 50c, outer cooling holes 50d, and a central cooling hole 52. The inner cooling hole 50c is formed in the -Z direction from the center of the inner resistor Rc. The outer cooling hole 50d is formed in the -Z direction from the center of the outer resistor Rd. The inner cooling holes 50c and the outer cooling holes 50d are formed in a substantially rectangular shape. The longitudinal directions of the inner cooling holes 50c and the outer cooling holes 50d are aligned with the longitudinal directions of the corresponding inner resistor Rc and outer resistor Rd. The central cooling hole 52 is formed in the -Z direction from the center of the three resistors Rc and Rd.

[0056] The inner cooling hole 50c is disposed in the -R direction of the unit base 16. The outer cooling hole 50d is disposed in the +R direction of the unit base 16. A portion of the central cooling hole 52 is blocked by the unit base 16, but the remaining portion is exposed in the +R direction of the unit base 16.

[0057] In Figure 3, the first current-limiting resistor R1 is energized from the time the first main valve VM1 opens until the first resistance valve VR1 opens. The second current-limiting resistor R2 is energized from the time the second resistance valve VR2 closes until the second main valve VM2 closes. The current-limiting resistor R0 (the first current-limiting resistor R1 and the second current-limiting resistor R2) generates heat when energized. Cooling of the current-limiting resistor R0 is required.

[0058] FIG. 12 is a side cross-sectional view of the diverter switch 10. In FIG. 12, the flow of insulating fluid is indicated by two-dot chain lines. As described above, when the main valve cam member 70 rotates in the θ direction, the insulating fluid flows in the Z direction of the main valve cam member 70. For example, consider the case where insulating fluid is pushed out from the main valve cam member 70 in the +Z direction. The main valve cam member 70 is disposed in the -R direction of the unit base 16. The insulating fluid flowing in the +Z direction from the main valve cam member 70 flows into the inner cooling hole 50c of the first mounting plate 12. The insulating fluid passes through the inner resistor Rc and reaches the ground shield 11.

[0059] The insulating fluid flows in the +R direction along the -Z direction surface of the ground shield 11. The +R direction peripheral edge of the ground shield 11 is curved in the -Z direction. The insulating fluid changes course in the -Z direction at the peripheral edge of the ground shield 11. The insulating fluid passes through the outer resistor Rd and flows into the outer cooling hole 50d (and the central cooling hole 52) of the first mounting plate 12. The insulating fluid continues to flow in the -Z direction and reaches the lower half of the switching unit 15.

[0060] Due to the heat generated by the current-limiting resistor R0, high-temperature insulating fluid is present around the current-limiting resistor R0. The insulating fluid that flows from the main valve cam member 70 in the +Z direction passes through the current-limiting resistor R0. At this time, the high-temperature insulating fluid is pushed out of the current-limiting resistor R0, and the low-temperature insulating fluid flows into the current-limiting resistor R0. This cools the current-limiting resistor R0.

[0061] When the insulating fluid is drawn in the -Z direction toward the main valve cam member 70, the insulating fluid flows in the opposite direction to the above. In this case, the current-limiting resistor R0 is also cooled. Note that the composite cam 65 shown in FIG. 10 has a through-hole 65h formed therein. The insulating fluid passes through the through-hole 65h of the composite cam 65 and flows across the composite cam 65.

[0062] As described above in detail, the changeover switch 10 of the on-load tap changer 1 of this embodiment includes the shaft 61, the main valves VM1 and VM2, the main valve cam member 70, and the current-limiting resistor R0. The main valves VM1 and VM2 connect and disconnect between the tap terminals T1 and T2 and the neutral point 18. The main valve cam member 70 is disposed between the shaft 61 and the main valves VM1 and VM2 in the R direction. The main valve cam member 70 rotates in the θ direction to drive the main valves VM1 and VM2. The current-limiting resistor R0 is disposed alongside the main valve cam member 70 in the Z direction. The current-limiting resistor R0 is connected between the tap terminals T1 and T2 and the neutral point 18. The main valve cam member 70 includes a cam ring 72, a hub 73, and multiple vanes 75. The cam ring 72 is disposed in the +R direction. The hub 73 is disposed in the -R direction. The vanes 75 are connected to the cam ring 72 and the hub 73, and intersect at an angle other than perpendicular to the Z direction. A plurality of vanes 75 are arranged with gaps in the θ direction.

[0063] The vanes 75 intersect at an angle other than perpendicular to the Z direction. This allows the insulating fluid to circulate in the Z direction as the main valve cam member 70 rotates. Multiple vanes 75 are arranged with gaps in the θ direction. This allows the insulating fluid to circulate in the Z direction across the main valve cam member 70. The current-limiting resistors R0 are arranged side by side in the Z direction of the main valve cam member 70. This allows a low-temperature insulating fluid to be supplied to the current-limiting resistors R0. Because the current-limiting resistors R0 are sufficiently cooled, a small current-limiting resistor R0 can be used. Furthermore, there is no need to add a special device to cool the current-limiting resistors R0. This allows the diverter switch 10 of the on-load tap changer 1 to be miniaturized. Furthermore, the cost of the diverter switch 10 can be reduced. Furthermore, because the current-limiting resistors R0 are sufficiently cooled, the diverter switch 10 can have a high capacity.

[0064] The main valves VM1, VM2 each have a valve body Vm and a lever 48. The valve body Vm is disposed along the Z direction. The lever 48 is L-shaped and rotatable around a rotation axis 48x that extends along the θ direction. The rotation axis 48x is disposed on the −R side of the valve body Vm. The lever 48 has a first arm 48a and a second arm 48b. The first arm 48a extends from the rotation axis 48x in the +R direction, and its tip is connected to the valve body Vm. The second arm 48b extends from the rotation axis 48x along the Z direction, and a roller 49 that abuts against the cam ring 72 is disposed on its tip.

[0065] Because the lever 48 is formed in an L-shape, the main valves VM1, VM2 are compact in the R direction. The main valves VM1, VM2 are arranged near the end of the diverter switch 10 in the +R direction. The main valve cam member 70 is arranged on the -R side of the main valves VM1, VM2. This allows the main valve cam member 70 to be formed with a large diameter, which increases the amount of insulating fluid that flows through it.

[0066] The cam ring 72 pushes the rollers 49 in the +R direction, driving the main valves VM1 and VM2. At this time, the cam ring 72 receives a reaction force in the -R direction, but not in the Z direction. The vane plate 75 is required to have compressive rigidity in the R direction, but not bending rigidity in the Z direction. Therefore, the vane plate 75 can be formed in a thin plate shape. Because the main valve cam member 70 is made smaller in size in the Z direction, the diverter switch 10 of the on-load tap changer 1 can be made smaller.

[0067] The current-limiting resistor R0 is supported by a first mounting plate 12 that is disposed between the main valve cam member 70 and the current-limiting resistor R0. A plurality of cooling holes 50 are formed in the first mounting plate 12. The insulating fluid flowing in the Z direction of the main valve cam member 70 passes through the current-limiting resistor R0 via the plurality of cooling holes 50. This allows the current-limiting resistor R0 to be efficiently cooled.

[0068] The cooling holes 50c and 50d are formed at positions overlapping the current-limiting resistor R0 in the Z direction. This allows the insulating fluid to easily pass through the current-limiting resistor R0, thereby efficiently cooling the current-limiting resistor R0.

[0069] The main valves VM1 and VM2 are mounted on a unit base 16. The main valve cam member 70 is disposed on the -R direction of the unit base 16. The ground shield 11 is disposed on the opposite side of the first mounting plate 12 in the Z direction with the current-limiting resistor R0 in between, and covers the current-limiting resistor R0. The multiple cooling holes 50c and 50d are formed separately in the -R direction and +R direction of the unit base 16. As a result, the insulating fluid turns around at the ground shield 11 and flows in the Z direction in the −R direction and +R direction of the unit base 16. Therefore, the current-limiting resistor R0 is efficiently cooled.

[0070] In the embodiment, the vanes 75 are formed on the main valve cam member 70. Alternatively, the vanes 75 may be formed on the resistance valve cam of the composite cam 65. Alternatively, the composite cam 65 may be separated into a resistance valve cam and a separation switch cam, and the vanes 75 may be formed on the resistance valve cam. Furthermore, the vanes 75 may be formed on both the main valve cam member 70 and the resistance valve cam.

[0071] According to at least one embodiment described above, the main valve cam member 70 has a plurality of vanes arranged with gaps in the θ direction. This allows the current-limiting resistor R0 to be sufficiently cooled, thereby enabling the diverter switch 10 of the on-load tap changer 1 to be made more compact.

[0072] Although several 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 within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0073] R0...current limiting resistor, R1...first current limiting resistor (current limiting resistor), R2...second current limiting resistor (current limiting resistor), T1...first tap terminal (tap terminal), T2...second tap terminal (tap terminal), VM1...first main valve (valve), VM2...second main valve (valve), Vm...valve body, 1...on-load tap changer, 10...changeover switch, 11...earth shield, 12...first mounting plate, 16...unit base, 18...neutral point terminal (neutral point), 48...lever, 48a...first arm, 48b...second arm, 48x...rotating shaft, 49...roller (cam follower), 50...cooling hole (through hole), 61...shaft, 70...main valve cam member (cam member), 72...cam ring, 73...hub, 75...vane.

Claims

1. A shaft, a valve for connecting and disconnecting between the tap terminal and the neutral point; a cam member disposed between the shaft and the valve in a radial direction of the shaft, and rotating in a circumferential direction of the shaft to drive the valve; a current-limiting resistor arranged alongside the cam member in the axial direction of the shaft and connected between the tap terminal and the neutral point; The cam member is a cam ring disposed radially outward; a hub disposed radially inward; a plurality of vanes connected to the cam ring and the hub, intersecting the axial direction at an angle other than perpendicular, and arranged with gaps in the circumferential direction; On-load tap changer changeover switch.

2. The valve is a valve body disposed along the axial direction; a lever formed in an L-shape and rotatable around a rotation axis along the circumferential direction, the rotation shaft is disposed radially inward of the valve body, The lever is a first arm extending radially outward from the pivot shaft and having a tip connected to the valve body; a second arm extending from the rotation shaft along the axial direction and having a cam follower disposed at a tip thereof and contacting the cam ring; 2. A diverter switch for an on-load tap changer according to claim 1.

3. the current-limiting resistor is supported by a mounting plate disposed between the cam member and the current-limiting resistor; A plurality of through holes are formed in the mounting plate.

3. A diverter switch for an on-load tap changer according to claim 1 or 2.

4. the plurality of through holes are formed at positions overlapping with the current-limiting resistors in the axial direction; 4. A diverter switch for an on-load tap changer according to claim 3.

5. The valve is mounted on a unit base, the cam member is disposed radially inward of the unit base, a ground shield disposed on the opposite side of the mounting plate with the current-limiting resistor interposed therebetween in the axial direction, the ground shield covering the current-limiting resistor; the plurality of through holes are formed separately on the inner side and the outer side in the radial direction of the unit base; 5. A diverter switch for an on-load tap changer according to claim 4.

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