Patent ID: 12255035

DETAILED DESCRIPTION

Embodiments of the present invention provide an on-load tap changer that generates significantly smaller torque peaks during actuation, has a simple and compact design, and at the same time ensures reliable operation.

According to a first aspect, the present invention provides an on-load tap changer for uninterrupted diverter switch operation between different winding taps of a tap changing transformer, comprising:a first module with a first module shaft;a second module with a second module shaft;the first module shaft actuates the first module;the second module shaft actuates the second module;the first and second module shafts are mechanically coupled to one another in such a way that the first module shaft drives the second module shaft and the second module is actuated with a time delay with respect to the first module.

Torque peaks are significantly reduced by dividing the on-load tap changer into individual modules and mechanically coupling the latter with an offset. This is achieved in that, although the elements to be actuated of the modules of the on-load tap changer are driven simultaneously, they are actuated one after the other with a slight offset. The offset is just large enough that no negative electrical interactions occur between the individual phases of a tap changing transformer, but the torque increases that occur are slightly offset from one another. This enables the use of a significantly simpler and therefore more advantageous motor. Furthermore, the individual parts of the drive shaft can be made smaller since they have to withstand smaller torque loads. This also has a positive effect on the cost of the entire switch. Without a mechanically offset coupling, the same elements would be moved or actuated in each module at the same time. The required force would add up, and this would require a drive with corresponding power.

Each module can be designed in any way as required and can include a module shaft, for example. The first module shaft of the first module is mechanically coupled to the second module shaft of the second module. The module shafts are mechanically connected to one another with an offset from one another in such a way that the individual modules are actuated with an offset from one another. In other words, although the two module shafts start rotating at the same time, the effect thereof (opening and closing of vacuum interrupters) on the elements in the modules takes place with a time delay.

The module shafts can be connected to one another in any way as required, for example via insulating bars, insulating shafts or chains.

The offset between the modules and in particular between the module shafts can be designed in any way as required, for example as offset connecting pins on the module shafts and identically designed insulating shafts or insulating shafts with offset receptacles and identical module shafts. How the offset between the module shafts is ultimately realized is irrelevant.

The diverter switch can be designed in any way as required and can, for example, comprise at least two or more modules. The modules are each assigned to a phase of a tap changing transformer.

Each module can be designed in any way as required and can, for example, comprise at least one diverter switch and one selector. The diverter switch can include at least one switching element and one current-limiting element. The at least one switching element can be designed as a vacuum interrupter or as a simple mechanical switch. The current-limiting element is preferably a resistor, a reactor or a current-dependent resistor. The selector has at least one selector arm, preferably two selector arms as a tap selector and/or a change-over selector arm as a change-over selector.

Each module shaft can be designed in any way as required and, for example, can have a connecting pin, bolt, feather keys or any other connecting element at each end. The connecting pins are not axially parallel and are preferably offset from one another by a maximum of 15 degrees. The connecting pins, bolts or feather keys can be inserted only on one side or extend through the entire module shaft.

Each module shaft can be designed in any way as required and, for example, can have a first connecting pin at a first end and a second connecting pin at a second end. The first connecting pin may run along a first axis A and the second connecting pin may run along a second axis B, wherein the axes A and B are not axially parallel and are preferably offset by an angle of a maximum of 15 degrees.

The drive can be designed in any way as required and, for example, can include at least one motor and/or a gear unit. The motor can be designed as a synchronous motor with a multi-turn absolute encoder or as a DC motor with microswitches.

Provision can be made for the module shafts and the insulating shafts to be connected via couplings and/or couplings with a plurality of coupling brackets.

Provision can be made for a motor to be connected directly to the drive shaft or indirectly to the insulating shaft or the first module shaft of the on-load tap changer via a gear unit, bevel gear or linkage.

Identical reference signs are used for elements of the invention that are identical or functionally identical. Furthermore, for the sake of clarity, each of the individual figures contains only those reference signs necessary for the description of said figure. The illustrated embodiments merely illustrate examples of how the on-load tap changer according to the invention can be designed and therefore do not represent a final delimitation of the invention.

FIG.1shows a schematic design of an on-load tap changer1according to an embodiment of the invention. The latter has a first module20, a second module40, and a third module60. Each of the modules20,40,60is assigned to a phase of a tap changing transformer. The first module20has a first module shaft22. The first module shaft22is connected or coupled at its first end23to a drive2. The drive2is designed as a motor drive with or without a gear unit and is preferably mechanically connected to the first end23of the first module shaft22via a first insulating shaft21. The first module20has a diverter switch30and a selector35. The diverter switch30and in particular the vacuum interrupters thereof are actuated directly via the first module shaft22. Here, two cam disks32are seated on the first module shaft22and, as they rotate, open and close the vacuum interrupters. Furthermore, on the first module shaft22there is a first bevel wheel36which drives a second bevel wheel37which, in turn, actuates the individual selector arms of the selector35. During driving of the first module shaft22, the diverter switch30and the selector35are thus actuated in a specific order; the first module20of the on-load tap changer1is actuated.

Furthermore, the on-load tap changer1has a second module40and a third module60. The three modules20,40,60are constructed identically to one another. The three modules are also mechanically coupled to one another via a second and a third insulating shaft41,61. The drive2drives the first module20via the first insulating shaft21, the first module20drives the second module40via the second insulating shaft41, and the second module40drives the third module60via the third insulating shaft61. The second and the third module40,60each also have a diverter switch50,70, a selector55,75and module shafts42,62. The respective selectors55,75are driven via respective bevel wheels56,57,76,77.

FIG.2ashows a detailed view of the first module shaft22which has a first connecting pin24at its first end23. The first module shaft22is connected to the drive2via this first connecting pin24, for example via a first insulating shaft21. Furthermore, the first module shaft22has a second connecting pin26at its second end25. The second connecting pin26is not arranged axially parallel to the first connecting pin24on the module shaft22. In other words, the second connecting pin26is offset by a few degrees from the first connecting pin24. Bolts, feather keys or any other connecting element can be used as an alternative to the connecting pins. The connecting pin can protrude only on one side or extend from one side to the second, opposite side.

FIG.2bshows a front view of the module shaft22. Axis A is intended to show the orientation of the first connecting pin24. Axis B shows the orientation of the second connecting pin26. The axes A and B are offset from one another at an angle W1of preferably a maximum of 15 degrees. If a second module shaft42were now placed behind the first module shaft22and connected to the latter, the first connecting pin44of the second module shaft42would run axially parallel to the axis B of the second connecting pin26of the first module shaft2. Each module shaft22,42,62is configured identically, i.e. the second connecting pin26,46,66is offset from the respective first connecting pin24,44,64. Axis C shows the orientation of the second connecting pin46of the second module shaft42. The angle W2between the axes B and C is identical to the angle W1between the axes A and B.

FIG.3shows a detailed view of two module shafts connected to one another, in particular the first module shaft22and the second module shaft42. The first connecting pin24at the first end23of the first module shaft22is offset from the second connecting pin26at the second end25. The first end23of the first module shaft22is connected to a drive2via a first insulating shaft21. The connection between the first insulating shaft21and the first module shaft22is realized by means of a coupling19, which preferably has two coupling brackets. However, any type of coupling may be used. The second end25of the first module shaft22is connected to the first end43of the second module shaft42via a second insulating shaft41. As now becomes clear, the first connecting pins24,44of the respective module shafts22,42are connected to one another with an offset from one another. As soon as the drive2begins to rotate or drive the first insulating shaft21, the other shafts also rotate therewith. However, the modules20,40,60are actuated at an offset, since the cam disks and also the first bevel wheel of the second module40or third module60are offset from the cam disks and from the first bevel wheel of the first module20.

The insulating shafts41,61are configured identically here, i.e. the couplings19at the respective ends are identical. As an alternative to the module shafts with offset connecting pins, the insulating shafts can also have offset couplings at the respective ends. This also results in an offset mechanical coupling of the modules. The modules are driven simultaneously and together, but actuated with a time delay.

FIG.4shows a detailed view of one of the module shafts20,40,60, in particular the first module shaft20, wherein the second and third module shaft40,60are constructed identically. Two cam disks32for actuating the vacuum interrupters and a first bevel wheel36for actuating the selector35are arranged on the module shaft20. Within a 360 degree rotation of the module shaft20, the diverter switch30and the selector35are actuated. Depending on where the module shaft20is located, individual actions in the on-load tap changer, such as opening or closing the vacuum interrupters of a switching sequence, are carried out at a specific point in time. As soon as at least two module shafts40,60are coupled with an offset from one another, the actions in the second module40take place correspondingly with a slight offset from the first module20; finally, the modules20,40,60are constructed identically. Although the second module40is driven at the same time as the first module20, the actual actuation of the second module40(opening or closing of the vacuum interrupters) takes place with a time delay.

As an alternative to the module shafts20,40,60with offset connecting pins, the insulating shafts could also have offset receptacles at the two ends. The module shafts are therefore also mechanically connected with an offset from one another.

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.

LIST OF REFERENCE SIGNS

1On-load tap-changer2Drive19Coupling20First module21First insulating shaft22First module shaft23First end of2224First connecting pin of2225Second end of2226Second connecting pin of2230Diverter switch32Cam disks35Selector36First bevel wheel37Second bevel wheel40Second module41Second insulating shaft42Second module shaft43First end of4244First connecting pin of4245Second end of4246Second connecting pin of4250Diverter switch55Selector60Third module61Third insulating shaft62Third module shaft63First end of6264First connecting pin of6265Second end of6266Second connecting pin of6270Diverter switch75Selector