Patent Application
20220344079
The invention relates to a resistor assembly for a tap changer and to a tap changer having such a resistor assembly.
German patent application DE 42 31 353 A1 discloses a tap changer. A current-limiting resistor is connected to one of the tap selectors at one end and to the neutral point at its other end. The resistor is installed in a fixed and unchangeable manner.
German utility model DE 77 07 461 U discloses a diverter switch resistor. The diverter switch resistor consists of round, oval, rectangular or square resistor material with rounded edges, which resistor material is bent into resistor spirals and installed in chambers in a self-supporting manner. The bent resistor spiral is installed in a chamber formed from two insulating material bars.
Tap changers, in particular on-load tap changers, are used for uninterrupted switching between winding taps of a transformer. In on-load tap changers that are based on the high-speed resistor switching principle, the circulating current that flows during the intermediately simultaneous contacting of the currently connected tap contact and the preselected new tap contact in the event of switching is limited by ohmic resistors, and thereby, ensures an uninterrupted change in the transmission ratio of the transformer. The ohmic resistor has to be designed depending on the specific circuit topology, the individual operating conditions as well as the load current and the step voltage, that is to say in particular in accordance with the respective application of the on-load tap changer. Here, the voltage that is present between the currently connected tap contact and the preselected tap contact of the on-load tap changer is referred to as the step voltage. The resistor design is complicated and affects the entire manufacturing process, in particular the assembly process of the tap changer. This is because a different number and dimensioning of the resistors is required depending on the application, and therefore the structural design of the tap changer also has to be adapted under certain circumstances. This results in a large number of different variants of tap changers depending on their respective application. At present, the tap changer is fitted with the required transition resistors during assembly according to the resistance value determined for the specific order and then fully assembled. In view of the high number of variants, this leads to increased effort when assembling the tap changer.
In an embodiment, the present disclosure provides a resistor assembly that can be used in a tap changer. The resistor assembly may include: a resistor element, which is held by at least two resistor holders; a base plate with at least one opening and on which the at least two resistor holders holding the resistor element are arranged; a plurality of guides, respectively formed in each of the resistor holders and being configured to position a first end and a second end of the resistor element with respect to a longitudinal direction between the two resistor holders; and contact points of the resistor element, the contact points being electrically contacted by contacts of the tap changer in a condition where the resistor element is inserted into the resistor holder.
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:
Aspects of the present disclosure provide an improved concept for a resistor assembly for a tap changer, which resistor assembly can be easily and quickly adapted to different applications of the tap changer and in so doing ensures the operational reliability of the tap changer.
A resistor assembly, according to an embodiment of the invention, for a tap changer comprises at least one resistor element, which is held by at least two resistor holders. The resistor holders are provided at least on a base plate with at least one opening, on which base plate the at least two resistor holders for receiving the resistor element are arranged. The resistor element can be inserted into the resistor holder guide provided in the resistor holder through the opening. Guides are formed in each resistor holder. Each guide of the two resistor elements positions a first end and a second end of the resistor element with respect to a longitudinal direction between the two resistor holders. In each case one contact point of the resistor element is electrically contacted by contacts of the tap changer when a resistor element is inserted into the resistor holder.
The improved concept for the tap changer having a resistor assembly has the advantage that it becomes possible to change or to replace the resistors easily and quickly when needs change (such as, for example, when there is a change in the operating conditions of the tap changer) and still ensure the operational reliability of the tap changer in so doing.
According to one possible embodiment of the resistor assembly for a tap changer, the, in each case, one contact point of the resistor element is provided in an edge region at the first end and at the second end of each resistor element.
According to one possible embodiment of the resistor assembly for a tap changer, each resistor holder comprises a guide for fixing the resistor element. Each guide can be formed as a slot with a closed end and an open end. The slot is provided, at least in part, with a side wall, which can extend partially along the slot. The resistor element can be pushed in via the open end of the slot. In this case, the resistor assembly is formed in such a way that, after the tap changer has been assembled, the resistor element is fixed between the at least two resistor holders by means of the guide of the resistor holders.
According to one possible further embodiment, the guide can comprise a holding element, which can be in the form of a reversibly and elastically pivotable leg with a snap-action hook provided at a free end. The snap-action hook secures the resistor element pushed into the guide and holds it in position between the two resistor holders. The elastically pivotable leg gives way when the resistor element is pushed into the guide and in so doing likewise forms a part of the guide.
According to one possible embodiment of the invention, the at least one resistor element comprises a resistor carrier and a current-limiting element.
According to one possible embodiment of the invention, the resistor carrier can be in the form of a plate and the current-limiting element can be in the form of a metal wire which is wound around the plate. According to one possible embodiment, the resistor carrier can be in the form of a frame and the current-limiting element can be in the form of one or more metal springs which are clamped into the frame.
According to one possible embodiment of the invention, each resistor element can have a respective edge region at the first end and at the second end, which edge region is free of the current-limiting element. The closed end of the guide defines an end position for the resistor element in the resistor holder. As a result, in each case a part of the edge region of the resistor element substantially interacts in a positively locking manner with the slot of the guide.
The interaction in a positively locking manner essentially means that the edge regions of the resistor element are surrounded at least partially in a positively locking manner, that is to say with a precise fit, by the guide at least on three sides. The open end of the guide thus forms an open side of the guide, via which open side the resistor element can be pushed into the resistor holder. When the at least one resistor element is pushed into the guide, the elastically pivotable leg gives way and the at least one resistor element, when it has reached the end position in the guide, is locked in said guide.
According to at least one possible embodiment, the snap-action hook forms a part of the guide of the resistor holder in such a way that the snap-action hook surrounds the resistor element at least in part when it has reached the end position in the guide and thereby locks it in the end position. The snap-action hook can also be easily released from the locking position, so that the resistor element can be removed again and, for example, replaced by another one (with a different specification).
According to at least one possible embodiment, the resistor holder and the guide are formed in one piece and from insulating material. According to at least one embodiment, the resistor holder, the guide and the holding element are formed in one piece. The resistor holder can preferably be manufactured from a plastic using an injection-molding process.
According to at least one possible embodiment, the base plate has at least one opening in the region of the at least two resistor holders, which opening is formed in such a way that the at least one resistor element can be fixed between the at least two resistor holders by means of the guides of the resistor holders through the opening.
This allows the resistor elements (resistors) to be inserted after the tap changer has been assembled and allows the tap changer to be easily adapted to different applications by replacing the resistor elements. In this way, the electrical contacting of the resistor elements is also ensured.
According to one possible embodiment, the at least one opening can be substantially rectangular.
According to one possible embodiment of the invention, the resistor element can comprise two contact points composed of electrically conductive material, which are electrically conductively connected to the current-limiting element. The contact points of the resistor element are provided substantially in an edge region at the first end and at the second end of each resistor element.
According to one possible embodiment, each contact point is in the form of a metal plate.
According to one possible embodiment, the resistor assembly comprises at least two contacts which can connect the resistor element to current-carrying lines of the tap changer via the at least one contact point. The contacts can be in the form of spring contacts. The resistor element is preferably electrically conductively connected to the take-off lead and/or contacts and/or switches and/or other current-carrying components of the tap changer via the current-carrying lines. The contacts can be, for example, selector contacts and corresponding tap contacts via which the voltage ratio of the transformer windings is preselected or set. The switches can be in the form of, for example, vacuum interrupters and/or other mechanical switching elements via which the diverter switch operation from the currently connected tap contact to the preselected tap contact is performed. According to at least one embodiment, the contacts are in the form of spring contacts which are formed with a defined mechanical preload in such a way that the spring contacts press against the contact points of the resistor carrier when the resistor element is positioned in the resistor holders.
According to one possible further embodiment, the contacts can be integrated into the resistor holder. The contacts would also make up a part of the guide, for example.
According to one possible further embodiment of the invention, the at least two resistor elements can be arranged substantially parallel to one another and/or one above the other in the vertical direction between the resistor holders.
According to one possible embodiment of the invention, the at least two resistor elements form a resistor module.
According to the improved concept, a tap changer which comprises the resistor assembly according to the invention is also specified.
According to one possible embodiment of the invention, the tap changer comprises at least the first base plate and a second base plate, which are held in a spatial relationship to one another via at least two resistor holders.
According to one possible embodiment of the invention, the at least two resistor holders can be arranged perpendicularly to the at least two base plates.
According to one possible embodiment of the invention, the at least two resistor holders can be arranged between the at least two base plates.
According to one possible embodiment of the invention, the two resistor holders can be arranged parallel to one another.
In the following, the invention is 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 figure in which they first appear. The explanation is not necessarily repeated in the subsequent figures.
Identical reference signs are used for elements of embodiments 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. Components of the tap changer that are irrelevant to the following description of the resistor assembly have not been shown in these figures for the sake of clarity. The figures merely illustrate exemplary embodiments of the invention without, however, limiting the invention to the illustrated exemplary embodiments.
Each resistor holder 30 has, as shown in
Using a resistor assembly 10 or a tap changer 1 according to the improved concept, it is possible to equip the tap changer 1 in a flexible manner, that is to say with the required resistor elements 20 with regard to the size of the resistor (ohmic resistor) depending on the application. According to the improved concept, the resistor elements 20 can also be used after the assembly of the complete tap changer 1 and, if necessary, for example when the operating conditions of the tap changer 1 change, can also be easily replaced. As a result, the tap changer 1 can be built independently of the order and as a stock item. For example, the adaptation to the respective application of the tap changer 1 could also be completely outsourced from the manufacturing process, and the resistors could be installed into the tap changer only on site by the transformer manufacturer or the grid operator.
It is assumed that the present disclosure and many of the attendant advantages thereof can be understood from the above description. Further, it is evident 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 |
|---|---|---|---|
| 10 2019 126 168.6 | Sep 2019 | DE | national |
This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/074987, filed on Sep. 8, 2020 and claims benefit to German Patent Application No. DE 10 2019 126 168.6, filed on Sep. 27, 2019. The International Application was published in German on Apr. 1, 2021 as WO 2021/058272 A1 under PCT Article 21(2).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/074987 | 9/8/2020 | WO |
