The present disclosure relates to an on-load tap changer for uninterrupted diverter switch operation between different winding taps of a tap-changing transformer.
On-load tap changers conventionally consist of a selector for preselecting, in a powerless manner, the respective winding tap of the transformer which is to be switched to, and an on-load tap changer for actually switching loads from the previous winding tap to the new, preselected winding tap. The switching takes place by means of mechanical actuation of different switches and contacts of the selector and of the diverter switch, which is initiated by a motor drive and a drive shaft. Furthermore, the on-load tap changer, together with the motor drive and the control cabinet in which the motor control is located, may be mounted on the transformer housing from the outside (what is known as a “bolt-on tap changer”).
Document GB 1 114 868 A discloses a three-phase on-load tap changer in a container, which is attached to the side of the wall of an oil-fired boiler of a transformer. The on-load tap changer comprises a selector that preselects the winding taps of the transformer in a powerless manner by means of movable selector contacts, and a diverter switch having two vacuum switches by means of which the actual diverter switch operation is carried out. The individual switching and contact elements of the selector and of the diverter switch are actuated via a toothed gearing.
In the case of on-load tap changers in operation, for example as a result of a change in the requirements on the on-load tap changer, or after a decades-long operating life and accompanying signs of ageing of the on-load tap changer, it may be necessary to replace the on-load tap changer. When replacing an old on-load tap changer with a new one, in addition to the technical requirements on the on-load tap changer, the conditions at the operating site, in particular the conditions in terms of space, should also be taken into consideration, since there is generally only a limited or defined amount of space available for the on-load tap changer.
If a new transformer is equipped with an on-load tap changer, then generally, the on-load tap changer is firstly mounted on the transformer, and then the transformer is transported together with the on-load tap changer to the operation site or end users. The transportation takes place for example on a train car or in a truck, and therefore only a limited amount of space is available for the transformer including the on-load tap changer and the accompanying motor drive with a control cabinet.
In an embodiment, the present disclosure provides an on-load tap changer that uninterruptedly switches between winding taps of a tap-changing transformer. The on-load tap changer includes: at least one selector configured to preselect, in a powerless manner, a selected winding tap of the winding taps; at least one diverter switch configured to actually switch loads from a previous winding tap to a preselected winding tap of the winding taps; at least one toothed gearing comprising a first gearwheel and a second gearwheel, the first gearwheel being assigned to the selector, and the second gearwheel being assigned to the diverter switch; and a drive shaft, which is configured to be actuated by a motor drive. The first gearwheel and the second gearwheel are directly interconnected mechanically in such a way that the first gearwheel and the second gearwheel are simultaneously actuatable. The drive shaft is configured to drive either the first gearwheel or the second gearwheel.
Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:
One or more aspects of the present disclosure provide an improved concept for an on-load tap changer, which can be mounted on the transformer in a space-efficient manner and in such a way that it can be adapted to the spatial conditions on site.
The on-load tap changer according to an aspect of the present disclosure comprises an on-load tap changer for uninterrupted switching between winding taps of a tap-changing transformer. The on-load tap changer comprises at least one selector unit for preselecting, in a powerless manner, a selected winding tap, at least one toothed gearing having a first gearwheel and a second gearwheel, the first gearwheel being assigned to the selector unit, and the second gearwheel being assigned to the diverter switch unit, and a drive shaft which is actuated by a motor drive. In this case, the first gearwheel and the second gearwheel are directly interconnected mechanically, in such a way that the gearwheels can be actuated simultaneously. The drive shaft can drive either the first gearwheel or the second gearwheel. Therefore either the first gearwheel is the driving wheel and the second gearwheel is the driven wheel, or vice versa. By means of the direct, mechanical coupling of the gearwheels, the selector unit and the diverter switch unit are actuated equally and centrally by the drive shaft. Directly means specifically without an intermediate member between the gearwheels.
The transmission ratio of the toothed gearing is preferably i=1. All types of motors are conceivable as a motor drive, e.g. motors operated with direct current, motors operated with alternating current, regulated and unregulated motor systems etc.
The improved concept has the advantage that, by means of the design of the on-load tap changer and in particular of the transmission which transmits the drive movement of the drive shaft equally to the actuation means of the selector and of the diverter switch, the drive shaft and the motor drive can be arranged in a variable manner. This makes it possible to react in a flexible manner to the limited space availability when transporting the transformer to the operation site, or to the spatial conditions at the operation site, for example a substation or a gas-insulated switchgear.
According to one possible embodiment, the at least one selector unit, the at least one diverter switch unit, the at least one toothed gearing and the drive shaft are arranged in a housing of the on-load tap changer. The housing is preferably sealed off from the outside.
According to one possible embodiment, the first gearwheel is mounted in a rotationally fixed manner on a first gear shaft, and the second gearwheel is mounted in a rotationally fixed manner on a second gear shaft.
According to one possible embodiment, the first gearwheel and the first gear shaft are formed as a single piece, and the second gearwheel and the second gear shaft are formed as a single piece.
According to one possible embodiment, the first gear shaft is rotatable about a first gear axis, and the second gear shaft is rotatable about a second gear axis, and 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.
According to one possible embodiment, the first gearwheel and the second gearwheel are each in the form of a bevel gearwheel.
According to one possible embodiment, the bevel gearwheels are formed in the basic shape of a truncated cone having a toothed lateral surface. The toothing can be in the form of straight or helical teeth. According to one possible embodiment, the first and the second bevel gearwheels slot together at the tips of the toothing.
According to one possible embodiment, the first and the second gearwheels have an identical design.
According to one possible embodiment, the drive shaft can be connected in a rotationally fixed manner either to the first gear shaft or to the second gear shaft via a coupling. The coupling is preferably in the form of a coupling having a plurality of coupling shells.
According to one possible embodiment, the drive shaft is arranged on the first gear axis and/or in the extension of the first gear shaft when driving the first gearwheel, and on the second gear axis and/or in the extension of the second gear shaft when driving the second gearwheel.
According to one possible embodiment, the motor drive is fixed to the housing of the on-load tap changer by means of a transmission module. It can be provided that the transmission module is also in the form of a sealing module and seals off the interior of the housing of the on-load tap changer from the outside.
According to one possible embodiment, the on-load tap changer further comprises a control cabinet in which at least the control of the motor drive is arranged, and which is formed separately, i.e. physically separated from the motor drive. The control cabinet is preferably connected to the motor drive by means of a cable.
According to one possible embodiment, the control cabinet is fixed to a housing of the tap-changing transformer and/or to the housing of the on-load tap changer and/or to a suitable fixing means. The suitable fixing means can be for example a wall at the operation site of the tap-changing transformer.
According to one possible embodiment, the on-load tap changer is in the form of a three-phase on-load tap changer and comprises one selector unit, one diverter switch unit, one drive shaft and one toothed gearing per phase, that is to say three selector units, three diverter switch units, three drive shafts and three toothed gearings in total.
According to one possible embodiment, the on-load tap changer accordingly comprises a first, a second and a third selector unit, a first, a second and a third diverter switch unit, a first, a second and a third drive shaft, and a first, a second and a third toothed gearing. The first drive shaft actuates the first selector unit and the first diverter switch unit via the first toothed gearing. The second drive shaft actuates the second selector unit and the second diverter switch unit via the second toothed gearing. The third drive shaft actuates the third selector unit and the third diverter switch unit via the third toothed gearing.
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 toothed gearing, and the second drive shaft drives the third drive shaft via the second toothed gearing.
According to one preferred embodiment, the toothed gearings are in the form of bevel gearings.
According to one possible embodiment, the second and third drive shafts are located on a common axis.
According to one possible embodiment, the first, second and third drive shafts are located on a common axis.
According to one possible embodiment, each phase of the on-load tap changer comprises a first gearwheel and a second gear wheel in each case, and a first gear shaft and a second gear shaft in each case.
According to one possible embodiment, at least one second gear shaft is arranged between two drive shafts.
According to one possible embodiment, the drive shafts and the second gear shafts are interconnected in a rotationally fixed manner via at least one coupling.
In the following, aspects of the present disclosure are explained in detail on the basis of exemplary embodiments with reference to the drawings. Components which are identical or functionally identical or which have an identical effect may be provided with identical reference signs. Identical components or components having an identical function may in some cases be explained only in relation to the drawing in which they first appear. The explanation is not necessarily repeated in the subsequent drawings.
In this case, the drive shaft 60 is arranged on the first gear axis 33 in the extension of the first gear shaft 32 and is connected at the first end 61 thereof in a rotationally fixed manner to the first gear shaft 32 via the coupling 63. As a result, the drive shaft 60 directly drives the first gearwheel 31, which transmits the movement to the second gearwheel 41, which in turn is arranged on the second gear shaft 42 in a rotationally fixed manner. The rotational movement is transmitted from the second gear shaft 42 to the second drive shaft 80 via the coupling 84.
However, the arrangement of the control cabinet 72 is not limited to the embodiments shown. As a result of the flexible cable connection within a defined distance from the on-load tap changer 10, which is dependent for example on the cable length and/or the drive solution, the control cabinet 72 can in principle be fixed anywhere at the operation site of the transformer, for example to a nearby wall.
By means of an on-load tap changer 10 according to the improved concept, it is possible to react in a flexible manner to different spatial conditions during transportation to or directly at the operation site. The motor drive can be attached in a variable manner to the end face or side of the housing of the on-load tap changer. The control cabinet can likewise be arranged in a variable manner and separately from the motor drive and the on-load tap changer. This is advantageous for example when replacing an old on-load tap changer with a new one, since in some circumstances, there is only a limited amount of space available for attaching the new on-load tap changer to the transformer housing, for example the space that was previously occupied by the old on-load tap changer. The improved concept is further advantageous for example when transporting the transformer with the on-load tap changer. Especially in the case of bolt-on tap changers, in this case, additional space is taken up by the on-load tap changer with the accompanying motor drive and control cabinet. By means of the improved concept, it is possible to make optimum use of the space which is available for example on a train car or in a truck and to transport the on-load tap changer with the transformer in a space-efficient manner. In addition, the accompanying control cabinet according to the improved concept can also be transported separately and only mounted in a suitable location at the operation site afterwards (see
It is assumed that the present disclosure and many of the attendant advantages thereof can be understood from the above description. Furthermore, it is clear that various changes can be made to the shape, construction and arrangement of the components without departing from the disclosed subject matter or without sacrificing all material advantages. The embodiment described is merely explanatory and such changes are intended to be covered by the following claims. Furthermore, it is understood that the invention is defined by the following claims.
While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
Number | Date | Country | Kind |
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10 2019 130 457.1 | Nov 2019 | DE | national |
This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/075967, filed on Sep. 17, 2020, and claims benefit to German Patent Application No. DE 10 2019 130 457.1, filed on Nov. 12, 2019. The International Application was published in German on May 20, 2021 as WO 2021/094015 A1 under PCT Article 21(2).
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/075967 | 9/17/2020 | WO |