On-load tap changer

Abstract

An on-load tap-changer (10) for switching, without interruption, between winding taps (N1,...NJ,... NN) of a tapped transformer (1), said on-load tap-changer comprising: - at least one selector unit (30) for preselecting, without power, a designated winding tap (NJ); - at least one load transfer switch unit (40) for actually transferring a load from the previous winding tap (NJ-1) to the preselected winding tap (NJ); - at least one gear mechanism (50) comprising a first gear (31) and a second gear (41), said first gear (31) being associated with the selector unit (30) and said second gear (41) being associated with the load transfer switch unit (40); - and a driveshaft (60) that is operated by a motor drive (70), wherein: - the first gear (31) and the second gear (41) are directly mechanically operatively connected to each other so that the gears (31, 41) are operated simultaneously; - and the driveshaft (60) can drive either the first gear (31) or the second gear (41).

Description

[0001] The invention relates to an on-load tap changer for uninterrupted load switching between different winding taps of a tapped transformer.

[0002] Known on-load tap-changers typically consist of a selector for powerless pre-selecting the respective transformer winding tap to which switching is to take place, and a diverter switch for the actual load switching from the previous winding tap to the new, pre-selected winding tap. The switching is performed by mechanically actuating various switches and contacts of the selector and the diverter switch, which is initiated by a motor drive and a drive shaft. Furthermore, it is known from the prior art to mount the on-load tap-changer, including the motor drive and control cabinet containing the motor control system, externally on the transformer housing (so-called "surface-mounted switch").

[0003] Document GB 1 114 868 A discloses a three-phase on-load tap-changer in a container that is mounted on the side of the wall of a transformer's oil tank. The on-load tap-changer comprises a selector, which uses movable selector contacts to preselect the transformer's winding taps without power, and a diverter switch with two vacuum switches, which perform the actual load transfer. The individual switching and contact elements of the selector and diverter switch are actuated via a gear drive.

[0004] Document US 3 421 073 A discloses an on-load tap-changer according to the preamble of claim 1.

[0005] For on-load tap-changers in operation, it may be necessary to replace them, for example, due to a change in the requirements for the on-load tap-changer or after decades of operation and the associated signs of aging. When replacing an old on-load tap-changer with a new one, in addition to the technical requirements of the on-load tap-changer, the conditions at the site of use, especially the space constraints, must be taken into account, as the on-load tap-changer usually only has a limited or defined space.

[0006] When a new transformer is equipped with an on-load tap-changer, the on-load tap-changer is typically mounted on the transformer first, and then the transformer and on-load tap-changer are transported to the installation site or end customer. Transport may take place on a railcar or truck, for example, leaving only limited space for the transformer, including the on-load tap-changer and the associated motor drive with control cabinet.

[0007] The object of the invention is therefore to provide an improved concept for an on-load tap-changer which can be mounted on the transformer in a space-saving manner and can be adapted to the spatial conditions on site.

[0008] This object is achieved by the subject matter of the independent claim. Further embodiments are the subject matter of the dependent claims.

[0009] The on-load tap-changer according to the invention comprises an on-load tap-changer for uninterrupted switching between winding taps of a tapped transformer. The on-load tap-changer comprises at least one selector unit for powerless preselection to a selected winding tap, at least one gear mechanism with a first gear and a second gear, the first gear being assigned to the selector unit and the second gear to the diverter switch unit, and a drive shaft actuated by a motor drive. The first gear and the second gear are directly mechanically connected to one another such that the gears can be actuated simultaneously. The drive shaft can drive either the first gear or the second gear. Thus, either the first gear is the driving gear and the second gear is the driven gear, or vice versa.Due to the direct, mechanical coupling of the gears, the selector unit and the load diverter switch unit are actuated equally and centrally by the drive shaft. "Direct" specifically means there is no intermediate link between the gears.

[0010] The gear ratio of the gear transmission is preferably i = 1 All types of motors can be used as motor drives, e.g., DC motors, AC motors, and controlled and uncontrolled motor systems.

[0011] The improved concept has the advantage that the design of the on-load tap-changer, and in particular the gearbox, which transmits the drive shaft movement equally to the actuating elements of the selector and the diverter switch, allows the drive shaft and motor drive to be arranged variably. This allows for flexible responses to the limited space available during transport of the transformer to the installation site or to the spatial conditions at the installation site, for example, in a substation or gas-insulated switchgear.

[0012] According to one possible embodiment, the at least one selector unit, the at least one diverter switch unit, the at least one gear transmission, and the drive shaft are arranged in a housing of the on-load tap-changer. The housing is preferably sealed to the outside.

[0013] According to the invention, the first gear is mounted on a first gear shaft and the second gear is mounted on a second gear shaft in a rotationally fixed manner.

[0014] According to one possible embodiment, the first gear and the first gear shaft are formed in one piece and the second gear and the second gear shaft are formed in one piece.

[0015] According to the invention, the first gear shaft is rotatable about a first gear axis and the second gear shaft is rotatable about a second gear axis.

[0016] According to one possible embodiment, the first and second gear axes intersect at a defined angle. Preferably, the first and second gear axes intersect at an angle of 90 degrees.

[0017] According to one possible embodiment, the first gear and the second gear are each designed as a bevel gear.

[0018] According to one possible embodiment, the basic shape of the bevel gears is a truncated cone with a toothed outer surface. The toothing can be spur and / or helical. According to one possible embodiment, the first and second bevel gears coincide at the tooth tips.

[0019] According to one possible embodiment, the first and second gears are identical.

[0020] According to one possible embodiment, the drive shaft can be connected in a rotationally fixed manner to either the first gear shaft or the second gear shaft via a coupling. The coupling is preferably designed as a coupling with multiple coupling shells.

[0021] According to the invention, the drive shaft is arranged on the first gear axis when driving the first gear and on the second gear axis when driving the second gear.

[0022] According to one possible embodiment, the motor drive is attached to the housing of the on-load tap-changer by means of a gear module. The gear module can also be designed as a sealing module, sealing the interior of the on-load tap-changer housing from the outside.

[0023] According to one possible embodiment, the on-load tap-changer further comprises a control cabinet in which at least the control unit of the motor drive is arranged, and which is designed separately, i.e., spatially separated from the motor drive. Preferably, the control cabinet is connected to the motor drive via a cable.

[0024] According to one possible embodiment, the control cabinet is attached to a housing of the tap-changer and / or to the housing of the on-load tap-changer and / or to a suitable fastening means. The suitable fastening means can, for example, be a wall at the location where the tap-changer is installed.

[0025] According to one possible embodiment, the on-load tap-changer is designed as a three-phase on-load tap-changer and comprises a selector unit, a diverter switch unit, a drive shaft and a gear transmission per phase, i.e. a total of three selector units, three diverter switch units, three drive shafts and three gear transmissions.

[0026] According to one possible embodiment, the on-load tap-changer comprises a first, a second, and a third selector unit, a first, a second, and a third load diverter switch unit, a first, a second, and a third drive shaft, and a first, a second, and a third gear transmission. The first drive shaft actuates the first selector unit and the first load diverter switch unit via the first gear transmission. The second drive shaft actuates the second selector unit and the second load diverter switch unit via the second gear transmission. The third drive shaft actuates the third selector unit and the third load diverter switch unit via the third gear transmission.

[0027] According to one possible embodiment, the drive shafts are mechanically coupled to one another in such a way that the first drive shaft drives the second drive shaft via the first gear transmission and the second drive shaft drives the third drive shaft via the second gear transmission.

[0028] According to a preferred embodiment, the gear transmissions are designed as bevel gear transmissions.

[0029] According to one possible embodiment, the second and third drive shafts are located on a common axis.

[0030] According to one possible embodiment, the first, second and third drive shafts are located on a common axis.

[0031] According to a possible embodiment, each phase of the on-load tap-changer comprises a first gear and a second gear and a first gear shaft and a second gear shaft.

[0032] According to one possible embodiment, at least one second gear shaft is arranged between two drive shafts.

[0033] According to one possible embodiment, the drive shafts and the second gear shafts are connected to one another in a rotationally fixed manner via at least one coupling.

[0034] The invention will now be explained in detail using exemplary embodiments with reference to the drawings. Components that are identical, functionally identical, or have an identical effect may be provided with identical reference numerals. Identical components or components with identical functions may only be explained with reference to the figure in which they first appear. The explanation is not necessarily repeated in subsequent figures.

[0035] It shows Figure 1a schematic structure of a tap-changer with an exemplary embodiment of an on-load tap-changer according to the prior art; Figure 2 a schematic representation of the winding taps of a tapped transformer; Figure 3A a plan view of an exemplary embodiment of an on-load tap-changer according to the improved concept; Figure 3B a plan view of another exemplary embodiment of an on-load tap-changer according to the improved concept; Figure 4A a plan view of another exemplary embodiment of an on-load tap-changer according to the improved concept; Figure 4B a plan view of another exemplary embodiment of an on-load tap-changer according to the improved concept; Figure 5A a detailed view of the on-load tap-changer from the Figure 3A and 4A ; Figure 5B a detailed view of the on-load tap-changer from the Figure 3B and 4B ; Figure 6Aa schematic representation of a tap transformer with an exemplary embodiment of an on-load tap changer according to the improved concept; Figure 6B a further schematic representation of a tap transformer with an exemplary embodiment of an on-load tap changer according to the improved concept.

[0036] Figure 1 shows a schematic representation of a tap-changer 1 with an exemplary embodiment of a known on-load tap-changer 10, which is designed as a built-in switch. The on-load tap-changer 10 has a selector 30 and a load diverter switch 40 and is driven by a motor drive 70, the control of which is spatially housed in a switch cabinet 72. The on-load tap-changer 10, the motor drive 70, and the switch cabinet 72 are arranged in a housing 11.

[0037] Figure 2 shows schematically a control winding 2 of the step transformer 1 (see Fig. 1) with different winding taps N 1 , ..., NJ , ..., NN . The winding taps N 1 , ..., NJ , ..., NN are switched on or off by the on-load tap-changer 10. The switching on or off can be implemented by any means, such as a selector 30, a load diverter switch 40, etc. The on-load tap-changer 10 is operated via the motor drive 70.

[0038] Figure 3A shows an exemplary embodiment of an on-load tap-changer 10 according to the improved concept in plan view. The on-load tap-changer 10 comprises a housing 11, a selector unit 30 for powerless preselection of a selected winding tap N 1 , ..., NJ , ..., NN of a regulating winding 2 of a tapped transformer 1 (see Fig. 2), a load changeover switch unit 40, with which the actual load switching from the previous winding tap NJ to the preselected winding tap N J+1 (not shown) of the control winding takes place, and a gear mechanism 50, which is designed as a bevel gear mechanism and which has a first bevel gear 31 and a second bevel gear 41. The bevel gears 31 and 41 are designed as truncated cones with a toothed outer surface and are made of a metallic material, preferably steel. The teeth on the toothed outer surface are interlocked, so that the bevel gears 31 and 41 are in direct mechanical connection with one another, i.e. without an intermediate link. The first bevel gear 31 is assigned to the selector unit 30 and actuates it, and the second bevel gear 41 is assigned to the load changeover switch unit 40 and actuates it.Furthermore, the on-load tap-changer 10 has a drive shaft 60, which is connected at a first end 61 to the bevel gear 50 and at a second end 62 to a motor drive 70. The drive shaft 60 is preferably made of insulating material. The motor drive 70 is attached laterally to the housing 11 as an extension of the drive shaft 60 by means of a gear module 71, in particular a sealing module, which seals the interior of the housing 11 from the outside. According to this embodiment, the drive shaft 60 directly drives the bevel gear 41, i.e., the load diverter switch unit 40. Due to the mechanical operative connection between the bevel gear 31 and the bevel gear 41, the rotational movement of the bevel gear 41 is transmitted directly to the bevel gear 31, so that the selector unit 30 is actuated in the same way as the load diverter switch unit 40.

[0039] Figure 3Bshows a further exemplary embodiment of an on-load tap-changer 10 according to the improved concept in a top view. According to this embodiment, the drive shaft 60 directly drives the bevel gear 31, i.e., the selector unit 30. Due to the mechanical operative connection between the bevel gear 41 and the bevel gear 31, the load diverter switch unit 40 is actuated in the same way as the selector unit 30. The motor drive 70 is attached to the front of the housing 11 by means of the gear module 71 as an extension of the drive shaft 60.

[0040] Figure 4Ashows a further exemplary embodiment of an on-load tap-changer 10 according to the improved concept in plan view. By way of example, the on-load tap-changer 10 is constructed here as a three-phase on-load tap-changer and therefore comprises a total of three selector units 30, 81 and 91, three diverter switch units 40, 82 and 92, three drive shafts 60, 80 and 90, and three gear transmissions 50, 83 and 93. The drive shaft 60 actuates the selector unit 30 and the diverter switch unit 40 via the gear transmission 50, the drive shaft 80 actuates the selector unit 81 and the diverter switch unit 82 via the gear transmission 83, and the drive shaft 90 actuates the selector unit 91 and the diverter switch unit 92 via the gear transmission 93. The three, each divided into a selector unit 30, 81, 91, a diverter switch unit 40, 82, 92, a drive shaft 60, 80, 90 and a gear transmission 50, 83, 93 divisible phases are all arranged in a housing 11.The drive shafts 60, 80, 90 are arranged on a common axis A and mechanically coupled to one another such that the first drive shaft 60 drives the second drive shaft 80 via the gear transmission 50, and the second drive shaft 80, in turn, drives the third drive shaft 90 via the second gear transmission 83. The first drive shaft 60 is driven by the motor drive 70, which is arranged laterally on the housing 11 as an extension of the drive shaft 60. The drive shaft transmits the drive movement to the gear transmission 50. Thus, all three phases with the respective selector units 30, 81, 91 and the respective load diverter switch units 40, 82, 92 are driven centrally via the drive shaft 60.

[0041] In Figure 5A is a detailed view of the on-load tap-changer 10 from the Figure 3A and 4Awhich shows the mechanical coupling between the first drive shaft 60 and the second drive shaft 80 via the bevel gear 50. In the embodiment according to Fig. 4AThe coupling between the second drive shaft 80 and the third drive shaft 90 is constructed identically. The first bevel gear 31 is arranged in a rotationally fixed manner on a first gear shaft 32, and the second bevel gear 41 is arranged in a rotationally fixed manner on a second gear shaft 42. The gear shafts 32 and 42 are preferably made of a metallic material, e.g., steel. The first gear shaft 32 is rotatable about a gear axis 33, and the second gear shaft 42 is rotatable about a gear axis 43. The first gear axis 33 and the second gear axis 43 intersect in a plane at a defined angle α, which is preferably a right angle. The selector unit 30 comprises a driver 34 which is connected in a rotationally fixed manner to the first gear shaft 32 and actuates movable selector contacts (not shown) which actuate the winding taps N 1 , ..., NJ , ..., NN (not shown) of the control winding 2 of the tapped transformer 1 (see Fig. 2). The load changeover switch unit 40 comprises actuating means 44 for switching elements (not shown) with which the actual load switching from a winding tap NJ to the preselected winding tap N J+1 (not shown) of the control winding 2 (see Fig. 2) is carried out. The actuating means 44 are designed as cam disks 44 which are connected in a rotationally fixed manner to the gear shaft 42 and upon whose rotation the switching elements (not shown) are opened and closed, for example via a lever mechanism. The switching elements (not shown) can preferably be designed as vacuum interrupters. For example, one cam disk 44 is provided per vacuum interrupter. The drive shaft 60 is arranged as an extension of the second gear shaft 42 on the second gear axis 43 and is connected in a rotationally fixed manner to the second gear shaft 42 at the first end 61 via a coupling 63. The motor drive 70 is arranged at the second end 62 of the drive shaft 60 and drives the drive shaft 60 via a coupling 64.Within a 360-degree rotation of drive shaft 60 and gear shaft 42, the load diverter switch unit 40 is actuated and—due to the coupling of bevel gears 41 and 31—the selector unit 30 is actuated. Motion is transmitted between drive shafts 60 and 80 via clutch 63, the second gear shaft 42, and a further clutch 84, which connects drive shaft 80 to the second gear shaft 42 in a rotationally fixed manner. Clutches 62, 64, and 84 preferably each have two clutch shells. In principle, however, any type of shaft coupling can be used.

[0042] Figure 4B shows a further exemplary embodiment of an on-load tap-changer 10 according to the improved concept in plan view. This on-load tap-changer 10 is also designed as a three-phase switch. According to this embodiment, the motor drive 70 is analogous to the one shown in Fig. 3Bshown embodiment is arranged in extension of the drive shaft 60 on the front side of the housing 11, ie the drive shaft 60 directly drives the first gear 31, as will be explained below with reference to the description of the Fig. 5B The coupling between the second drive shaft 80 and the third drive shaft 90 is analogous to that in Fig. 5A shown arrangement.

[0043] Figure 5B shows a detailed view of the on-load tap-changer 10 from the Figure 3B and 4BHere, the drive shaft 60 is arranged as an extension of the first gear shaft 32 on the first gear axis 33 and is connected at its first end 61 via the coupling 63 in a rotationally fixed manner to the first gear shaft 32. Consequently, the drive shaft 60 directly drives the first gear 31, which transmits the movement to the second gear 41, which in turn is arranged in a rotationally fixed manner on the second gear shaft 42. The rotational movement is transmitted from the second gear shaft 42 to the second drive shaft 80 via the coupling 84.

[0044] Figure 6Ashows a schematic representation of a tap-changer 1 with an exemplary embodiment of an on-load tap-changer 10 according to the improved concept. According to this embodiment, the on-load tap-changer 10 is implemented as a built-on switch, which is housed in a housing 11 and arranged outside a transformer housing 3. The motor drive 70 is mounted on the side of the housing 11 of the on-load tap-changer 10. The associated control cabinet 72 is attached to the transformer housing 3 and connected to the motor drive 70 via a cable 73.

[0045] Figure 6Bshows a further schematic representation of a tap-changer 1 with an exemplary embodiment of an on-load tap-changer 10 according to the improved concept. According to this embodiment, the motor drive 70 is mounted on the front side of the housing 11 of the on-load tap-changer 10. The associated control cabinet 72 is also arranged on the front side of the housing 11 of the on-load tap-changer 10 and is connected to the motor drive 70 via a cable 73.

[0046] However, the arrangement of the control cabinet 72 is not limited to the illustrated embodiments. Due to the flexible cable connection, the control cabinet 72 can be mounted anywhere at the transformer's installation location, for example, on a nearby wall, within a certain distance from the on-load tap-changer 10, which depends, for example, on the cable length and / or the drive solution.

[0047] With an on-load tap-changer 10 according to the improved concept, it is possible to respond flexibly to different spatial requirements during transport to or directly at the place of use. The motor drive can be variably attached to the front or side of the on-load tap-changer housing. The control cabinet is also variably available and can be arranged separately from the motor drive and on-load tap-changer. This is advantageous, for example, when replacing an old on-load tap-changer with a new one, since the new on-load tap-changer may then only have limited space available for attachment to the transformer housing, for example the space previously occupied by the old on-load tap-changer. The improved concept is also advantageous, for example, when transporting the transformer with the on-load tap-changer. Especially with add-on switches, additional space is required by the on-load tap-changer with the associated motor drive and control cabinet.The improved concept makes it possible to make optimal use of the space available, for example, on a railway wagon or in a truck, and to transport the on-load tap-changer with the transformer in a space-saving manner. Furthermore, the associated control cabinet can also be transported separately according to the improved concept and subsequently installed at a suitable location at the installation site (see ). Fig. 6A and 6B ) so that it is possible to react flexibly to different spatial conditions during transport and at the place of use.

[0048] The described embodiment is merely illustrative, and such modifications are intended to be encompassed by the following claims. It is further understood that the invention is defined by the following claims. REFERENCE SIGNS

[0049] 1 Tap transformer 2 Regulating winding of 1 3 Transformer housing 10 On-load tap changer 11 Housing 30 Selector unit 31 First gear 32 First gear shaft 33 First gear axle 34 Driver of 30 40 Diverter switch unit 41 Second gear 42 Second gear shaft 43 Second gear axle 44 Cams / Actuator of 40 50 Gearbox 60 Drive shaft 61 First end of 60 62 Second end of 60 63 Coupling at first end 61 64 Coupling at second end 62 70 Motor drive 71 Gear module 72 Control cabinet 73 Cable 80 Second drive shaft 81 Second selector unit 82 Second diverter switch unit 83 Second gearbox 84 Coupling 90 Third drive shaft 91 Third Selector unit 92third load changeover switch unit 93third gear transmission αangle Aaxis N 1 , ...NJ , ..., NN Winding taps of 1

Claims

1. On-load tap-changer (10) for uninterrupted advanced retard switch between winding taps (N1, ...NJ, ..., NN) of a tapped transformer (1), comprising - at least one change-over selector unit (30) for powerless preselection to a selected winding tap (NJ) ; - at least one diverter switch unit (40) for the actual diverter switch operation from the previous winding tap (NJ-1) to the preselected winding tap (NJ) ; - at least one toothed gearing (50) with a first gearwheel (31) and a second gear wheel (41), the first gear wheel (31) being assigned to the selector unit (30) and the second gear wheel (41) being assigned to the load changeover unit (40) - a drive shaft (60) which is actuated by a motor-drive unit (70) wherein - the first gearwheel (31) and the second gearwheel (41) are in direct mechanical operative connection with one another in such a way that the gearwheels (31, 41) can be actuated simultaneously ; - the first gearwheel (31) is mounted on a first gearwheel shaft (32) and the second gearwheel (41) is mounted on a second gearwheel shaft (42) in a rotationally fixed manner; - the first gear shaft (32) is rotatable about a first gear axis (33) and the second gear shaft (42) is rotatable about a second gear axis (43), characterized in that - the drive shaft (60) can drive either the first gearwheel (31) or the second gearwheel (41) wherein - the drive shaft (60) is arranged on the first gearwheel axis (33) when driving the first gearwheel (31) and on the second gearwheel axis (43) when driving the second gearwheel (42) .

2. On-load tap-changer (10) according to the preceding claim, wherein the at least one selector unit (30), the at least one diverter switch unit (40), the at least one toothed gearing (50) and the drive shaft (60) are arranged in a housing (11) of the on-load tap-changer (10).

3. On-load tap-changer (10) according to claim 1, wherein - the first and second gearwheel axes (33, 43) intersect at a defined angle (α).

4. On-load tap-changer (10) according to one of the preceding claims, wherein the first gearwheel (31) and the second gearwheel (41) are designed as bevel gears.

5. On-load tap-changer (10) according to one of the preceding claims, wherein the drive shaft (60) is rotationally fixedly connectable via a coupling (63) either to the first gear shaft (32) or to the second gear shaft (42).

6. On-load tap-changer (10) according to one of the preceding claims, wherein the motor-drive unit (70) can be attached to the housing (11) of the on-load tap-changer (10) by means of a gear module (71).

7. On-load tap-changer (10) according to one of the preceding claims, further comprising a control cabinet (72) which is formed separately from the motor-drive unit (70).

8. On-load tap-changer (10) according to one of the preceding claims, comprising - a second and a third selector unit (81, 91), - a second and a third diverter switch unit (82, 92), - a second and a third drive shaft (80, 90), - a second and a third toothed gearing (83, 93); wherein - the second drive shaft (80) actuates the second selector unit (81) and the second diverter switch unit (82) via the second toothed gearing (83), - the third drive shaft (90) actuates the third selector unit (91) and the third diverter switch unit (92) via the third toothed gearing (93).

9. The on-load tap-changer (10) according to claim 8, wherein - the drive shafts (60, 80, 90) are mechanically coupled to one another in such a way that the drive shaft (60) drives the second drive shaft (80) via the toothed gearing (50), the second drive shaft (80) drives the third drive shaft (90) via the second toothed gearing (83).

10. An on-load tap-changer (10) according to claim 8 or 9, wherein - the second drive shaft (80) and the third drive shaft (90) are located on a common axis (A).

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