Patent Application
20170069439
The present invention relates to a position indicator for a tap changer of a tapped transformer.
For the purpose of changing the transmission ratio of an oil-insulated transformer under load, so-called tap changers or, as the case may be, on-load tap changers are provided, the structure and function of which are in principle known and that are formed for switching the winding taps of a tap winding of a transformer.
Such an on-load tap changer, which is connected to the tap winding, usually has a load diverter switch and a selector, and the selector preferably consists of a preselector and a fine selector. The fine selector is provided for the powerless selection of the winding tap of the tap winding and of the preselectors, which winding tap is to be connected, for the purpose of increasing the regulating range, where, according to application, the preselector can be formed either as change-over selector for the boost and buck connection of the tap winding or as coarse selector for the linkage of the tap winding to the beginning or to the end of the main winding of the transformer.
The load transfer in itself is carried out by the load diverter switch of the on-load tap changer, specifically from the previous to the new, preselected winding tap of the transformer tap winding. For this purpose, the load diverter switch usually has mechanical switch contacts and resistance contacts, where the switch contacts serve for direct connection of the respective winding taps to the load dissipation, and the resistance contacts serve for temporary bridging by one or more transition resistances. The developments of the past years, however, lead away from load diverter switches with mechanical switch contacts and toward using vacuum switching tubes or semiconductor switching components, in particular circuit breaker components, as switching components for high voltages and currents, for example thyristors, GTOs, IGBTs, and other components.
Integrated on-load tap changers, which are also called load selectors, are another genus of on-load tap changers. In these, the load diverter switch and the fine selector are constructed as one unit. Upon actuation, the winding tap to be switched is preselected and subsequently switched in a single step. This form of realization of an on-load tap changer can also have a preselector that is mounted either outside of or inside the housing of the on-load tap changer, specifically in an insulation medium, preferably in insulation oil.
Such tap changers in addition generally have a position indicator by aid of which the present switching position is displayed in the area of the cover closing the load diverter switch by means of a display disk that is coupled with the drive of the selector via a transmission gear. While the selector, which is subject to practically no wear, remains unaffected, the load diverter switch has to be removed at certain intervals for inspection purposes. As a result, it is necessary to take technical precautions for the position indicator to prevent the display from being readjusted in relation to the present switching position of the tap changer during inspection works. This is particularly difficult if the position indicator is directly tapped from the selector, which has to be done, in particular, in the instance of the transmission for the selector being mounted between load diverter switch and selector.
The number of potential switching positions varies greatly depending on the division of the fine selector and also of the preselector. The position indicator therefore has to be able to offer up to over 100 switching positions. In the position indicators as known from the prior art, the amount of numbers to be accommodated on the display disk is, however, essentially limited by the diameter of the display disk as well as by the fact that the switching angle of the transmission gear and the digits for the display cannot be realized in an arbitrarily small size.
The object of the invention is to specify a position indicator for a tap changer of a tapped transformer, which position indicator eliminates the previously mentioned disadvantages.
This object is fulfilled by a position indicator according to the independent claim. Advantageous developments and embodiments of the invention are described in the dependent claims.
The invention proposes a position indicator comprising
where
The invention is based on the knowledge that more than 100 different switching positions of the tap changer can be specified in an easy and compact way by the specific arrangement of numbers on the display disks in the interaction with the indicator gear, as a potential switching position can be expressed as a combined multi-digit number by the first display disk expressing the ones digit and by the second display disk expressing the tens digit. Each switchover thus causes the first display disk to rotate by the indicator gear by a definable circle sector of preferably 36 degrees such that the next ones digit of the first display disk comes to be positioned opposite to the expressed tens digit in the tangential area of the display disks. When the ones digit 9 is swept over to 0, the second display disk comes into engagement by the indicator gear via the mechanical coupling such that in said switchover, the tens digit is also changed in descending order or, as the case may be, in ascending order, by one digit, that is, from 0 to 1, or alternatively from 1 to 0, for example. In this way, it is possible for the switching position 09 to be changed over to 10 or, as the case may be, for the switching position 10 to be changed over to 09 to be expressed by a combined multi-digit number.
It can be provided that
It can be provided that
The Geneva driver is preferentially mounted on a top side of the drive wheel and can support a roller component. The Geneva wheel is preferentially mounted on a top side of the driven wheel.
It can be provided that
Preferentially, the blocking disk is mounted under the Geneva driver and the blocking cam is mounted under the Geneva wheel.
It can be provided that
It can be provided that
Each row of numbers can be formed in any manner as required and can comprise a different amount of numbers and/or different numbers, for example.
It can be provided that each of the proposed position indicators comprises
This has the advantage that no individual components have to be separately de-installed for maintenance purposes, but that it is rather possible to remove or de-install or, as the case may be, put in or install the entire position indicator as one module.
It can be provided that each of the proposed position indicators comprises
It can be provided that
Preferably, the first gear teeth are mounted at the bottom side of the drive wheel, and the second gear teeth are mounted at the bottom side of the driven wheel.
It can be provided that
It can be provided that
It can be provided that each of the proposed position indicators comprises
In this instance, it is particularly advantageous for the display disks to be mounted outside of a cover of the tap changer.
In the following, embodiments of the invention are explained in detail by the attached drawings. The individual features thereof are, however, not limited to the individual embodiments but can be connected and/or combined with individual features described further above and/or with individual features of other embodiments. Each example in the illustrations is provided by way of explanation, not limitation of the invention. The reference characters included in the claims are by no means intended to limit the scope of protection, but rather merely refer to the embodiments shown in the figures, in which
In this embodiment, the position indicator 1 comprises a display device 51, an indicator gear 10 and a base plate 5.
Movement tapping of the position indicator gear of the tap changer is thus carried out via an indicator shaft 2. At the top end, meaning the end facing toward the position indicator 1, a bushing 3 is, for example, slipped over the indicator shaft 2 and mechanically fastened to the indicator shaft 2 by fixing components 4.1 and 4.2, in particular by pins or screws. The position indicator 1 moreover has a supporting base plate 5 by means of which the position indicator 1 can be mounted together with a support arm 50 on an area of an oil vessel 6 of the tap changer, which oil vessel 6 is only illustrated in extracts here. For this purpose, the base plate 5 has bores 7.1 and 7.2 for being screwed to a recess provided in the oil vessel 6, for example. Provided at the base plate 5, there is moreover a plurality of spacers 8 that hold a further plate 9 spaced apart from the base plate 5.
An indicator gear 10 with a drive wheel 11 and a driven wheel 12 is positioned between the base plate 5 and the further plate 9. Particularly preferentially, the indicator gear 10 is a stepping gear, in particular a Geneva drive. At a top side 13, the drive wheel 11 for this purpose has a Geneva driver 14.1 that can only be seen in
The driven wheel 12 here takes the form of a Geneva wheel 12.1, in particular a Geneva star wheel, with a plurality of engagement components 31 and a blocking cam 18. The driven wheel 12 is then also non-rotatably connected by a second pivot pin 27. Moreover, the driven wheel 12 also comprises gear teeth 20 at its bottom side 19 that is not illustrated in FIG. lb. How the individual components engage into each other during a switchover and mutually influence each other is explained in detail further below.
Mechanically coupled with the drive wheel 11 is a first display disk 21 that rotates together with the drive wheel 11 when it performs a rotation. Arranged in a circle on the first display disk 21 is moreover a first row of numbers 0 to 9. The mentioned mechanical coupling between drive wheel 11 and first display disk 21 can be particularly preferentially realized by a first pivot pin 22 that has a keyway at each of its oppositely located ends, which keyway at the one end is in operative connection with a first keyway corresponding to the drive wheel 11, and at its other end with a second keyway provided in the display disk 21 and with a key that is insertable into a respective keyway, however not illustrated in detail here.
Mechanically coupled with the driven wheel 12, on the other hand, is a second display disk 26 that rotates together with the driven wheel 12 when the latter performs a rotation. Arranged in a circle on the second display disk 26 is moreover a second row of numbers 0 to 10. The mentioned mechanical coupling between driven wheel 12 and second display disk 26 can be particularly preferentially realized by a second pivot pin 27 that has a keyway at each of its oppositely located ends, which keyway at the one end is in operative connection with a first keyway corresponding to the driven wheel 12, and at its other end with a second keyway provided in the display disk 26 and with a key that is insertable into the respective keyway, however not illustrated in detail here.
It is possible to realize 10 different switching positions by the first display disk 21 on which the row of numbers 0 to 9 is arranged. For this purpose, the indicator shaft 2 has to sweep across a 36-degrees angle of rotation for each switchover. In 9 out of 10 possible switching positions of the drive wheel 11, the blocking disk 14.2 is then in engagement with the blocking cam 18 of the drive wheel 12 such that only the drive wheel 11, however not the driven wheel 12, accordingly rotates. Only in one possible switching position does the roller component 15 of the Geneva driver 14.1 come into engagement with the engagement components 31 of the Geneva wheel 12.1 during the switchover, that is, during a rotation of the indicator shaft 2 by a defined angle of rotation of preferably 36 degrees, and the roller component 15 entrains the Geneva wheel 12.1 for as long as until the roller component 15 comes out of engagement with the respective engagement component 31. Moreover, the recess in the circle sector of the blocking disk 14.2 comes out of engagement with the blocking cam 18 of the driven wheel 12 during this switchover process such that a transfer of the rotation of the drive wheel 11 to the driven wheel 12 is released. The change of numbers from 9 to 0 as ones digit in the tangential area of the display disks 21 and 26 on the first display disk 21 is therefore assigned to this switchover process, since upon over-sweeping this series of numbers, the tens digit of the tangential area, which tens digit is expressed by the second display disk 26, accordingly also has to change. The switching operations can then also be carried out alternatingly such that it is possible to switch back and forth between two switching positions.
The position indicator 1 is preferably formed as pre-assemblable module and then comprises the first and the second display disk 21 and 26, the plate 9, the first and the second pivot pin 22 and 27, the indicator gear 10, and the base plate 5 that is spaced apart by the spacers 8. Particularly preferentially, the components of the pre-assembled module can also be made from a polymer, to which a glass fiber mixture can also be added according to application. As can be seen in
A second embodiment of the position indicator is schematically illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 106 475.5 | May 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/059059 | 4/27/2015 | WO | 00 |
