On-load tap changer

Abstract

The invention relates to an on-load tap changer (1) for uninterrupted switching between winding taps (N1,...Nj,..., Nn) of a step transformer (2). The on-load tap changer (1) comprises a selector (3) and a load transfer switch (4). The load transfer switch (4) consists of a first load branch (5.1) and a second load branch (5.2), each load branch (5.1, 5.2) having at least one vacuum interrupter (6.1, 6.2, 7.1, 7.2). Each vacuum interrupter (6.1, 6.2, 7.1, 7.2) can switch between an open state, in which the movable contact (11) and the fixed contact (12) do not touch, and a closed state in which the movable contact (11) and the fixed contact (12) touch in at least one contact point (13). Starting from the contact point (13), each vacuum interrupter (6.1, 6.2, 7.1, 7.2) has a defined spherical region (14). The load transfer switch (4) is designed in such a way that the vacuum interrupters (6.1, 6.2, 7.1, 7.2) are arranged in a housing (29) in such a way that parts of the load transfer switch (4) through which current flows are arranged outside the defined region (14).

Description

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

[0002] Known on-load tap-changers typically consist of a selector for powerless selection of the respective transformer winding tap to which switching is to take place, and a load transfer switch for the actual load switching from the previous winding tap to the new, selected winding tap. Switching is performed by mechanically actuating different switches. With increasing load, i.e., higher currents and voltages, the demands on the actuating mechanism also increase. Document JP2017041478A discloses an on-load tap-changer according to the preamble of claim 1.

[0003] It is therefore an object of the present invention to provide an improved on-load tap-changer which can withstand the increased mechanical and electrical loads at higher currents and voltages.

[0004] This object is solved by the subject matter of independent claim 1. Further embodiments are the subject matter of the dependent claims.

[0005] According to the improved concept, an on-load tap-changer for uninterrupted switching between winding taps of a tapped transformer is specified, which has a selector for powerless preselection of a selected winding tap to which switching is to take place, and a load transfer switch for the actual load switching from the previous winding tap to the preselected winding tap. The load transfer switch comprises a first and a second load branch and at least one vacuum interrupter in the first and second load branches. Each vacuum interrupter has a movable contact and a fixed contact and can assume an open state in which the movable contact and the fixed contact do not touch, and a closed state in which the movable contact and the fixed contact touch at at least one contact point.Starting at the contact point, each vacuum interrupter has a defined, spherical area. The vacuum interrupters of the diverter switch are arranged in a housing such that current-carrying parts of the diverter switch are located outside the defined area. According to at least one preferred embodiment, the diverter switch is designed such that when the vacuum interrupters are actuated from the closed state to the open state, those parts of the diverter switch through which current is flowing at this time are located outside the defined area. This arrangement allows for a compact design of the on-load tap-changer while ensuring reliable operation, despite the increased currents and voltages.

[0006] According to the invention, the spherical region around the contact point has a radius of at least 80 mm and at most 200 mm.

[0007] According to at least one embodiment, current-carrying parts of the load diverter switch are a first electrical line of the first load branch and / or a second electrical line of the second load branch and / or a third electrical line of the first load branch and / or a fourth electrical line of the second load branch and / or electrically conductive connecting elements and / or a first mechanical switching contact and / or a second mechanical switching contact and / or switching resistors and / or vacuum interrupters in the closed state, which are arranged outside the spherical region of a vacuum interrupter.

[0008] According to the invention, the first load branch of the diverter switch comprises a first vacuum interrupter and a second vacuum interrupter.

[0009] According to at least one embodiment, at least the first line, the second line, the second vacuum interrupter of the first load branch, a third line and the first mechanical switching contact are arranged outside the defined region of the first vacuum interrupter of the first load branch.

[0010] According to at least one embodiment, the second load branch of the diverter switch comprises a first vacuum interrupter and a second vacuum interrupter.

[0011] According to at least one embodiment, at least the first line, the second line, the second vacuum interrupter of the second load branch, a fourth line and the second mechanical switching element are arranged outside the defined region of the first vacuum interrupter of the second load branch.

[0012] According to at least one embodiment, at least the second vacuum interrupter of the second load branch, the third line, the fourth line and the mechanical switching elements are arranged outside the defined region of the second vacuum interrupter of the first load branch.

[0013] According to at least one embodiment, at least the second vacuum interrupter of the first load branch, the third line, the fourth line and the mechanical switching elements are arranged outside the defined region of the second vacuum interrupter of the second load branch.

[0014] According to the invention, the first winding tap is electrically connected to a load derivation via a series circuit comprising a first vacuum interrupter and a second vacuum interrupter via the first load branch, and the second winding tap is electrically connected to the load derivation via a series circuit comprising a first vacuum interrupter and a second vacuum interrupter via the second load branch.

[0015] According to at least one embodiment, a switching resistor is arranged parallel to the first vacuum interrupter of the first and second load branches.

[0016] According to at least one embodiment, the switching resistors are arranged outside the defined region of the second vacuum interrupter of the first load branch and outside the defined region of the second vacuum interrupter of the second load branch.

[0017] According to the invention, the first mechanical switching contact is arranged between the second vacuum interrupter of the first load branch and the load derivation, and the second mechanical switching contact is arranged between the second vacuum interrupter of the second load branch and the load derivation.

[0018] According to at least one embodiment, the mechanical switching contacts are arranged outside the defined area of the vacuum interrupters.

[0019] According to at least one embodiment, the mechanical switching contacts are designed as disconnectors.

[0020] According to at least one embodiment, in the first load branch, the first and second vacuum interrupters are electrically connected to one another via the first electrical line and the second vacuum interrupter and the first mechanical switching element are electrically connected to one another via the third electrical line, and in the second load branch, the first and second vacuum interrupters are electrically connected to one another via the second line and the second vacuum interrupter and the first mechanical switching element are electrically connected to one another via the fourth line.

[0021] According to at least one embodiment, the electrical lines are each electrically connected to the vacuum interrupters via connecting elements.

[0022] According to at least one embodiment, the lines each have a first end and a second end, wherein the first end is electrically connected to the movable contact of the vacuum interrupter via the connecting element and the second end is electrically connected to the fixed contact of the vacuum interrupter via the connecting element.

[0023] According to at least one embodiment, a permanent main contact is additionally provided parallel to each load branch, which takes over at least part of the permanent current conduction during stationary operation and is in direct electrical connection with the load discharge.

[0024] According to at least one embodiment, the vacuum interrupters are arranged in a circle around a switching shaft.

[0025] According to at least one embodiment, the first and second mechanical switching contacts are arranged mirror-inverted to an axis, wherein the axis lies on the switching shaft.

[0026] According to at least one embodiment, two vacuum interrupters are arranged mirror-inverted to the axis.

[0027] The invention will now be explained in detail using exemplary embodiments with reference to the drawings. Components that are 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.

[0028] It shows Figure 1 shows a schematic representation of a tapped transformer with an on-load tap-changer according to the improved concept; Figure 2 shows a schematic representation of the winding taps of a tapped transformer; Figure 3 shows a schematic representation of an exemplary embodiment of an on-load tap-changer according to the improved concept; Figures 4a to 4f show an exemplary switching sequence of the on-load tap-changer from Figure 3 ; Figure 5 shows an exemplary embodiment of a load diverter switch according to the improved concept; Figure 6 shows a further view of the exemplary embodiment of Figure 5 ; Figure 7 shows a further view of the exemplary embodiment from Figure 5 ; and Figure 8 shows a further view of the exemplary embodiment from Figure 5 .

[0029] The figures merely illustrate embodiments of the invention, without, however, limiting the invention to the illustrated embodiments.

[0030] Figure 1shows a schematic representation of a tap-changer 2 with an on-load tap-changer 1, which has a selector 3 and a load diverter switch 4. The on-load tap-changer 1 is driven by a motor 22.

[0031] Figure 2 shows schematically a control winding 25 of the step transformer 2 (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 1. The switching on or off can be implemented by any means, such as a selector 3, a load diverter switch 4, etc. The on-load tap-changer 1 is operated by the motor 22.

[0032] Figure 3shows a schematic representation of an exemplary embodiment of an on-load tap-changer 1. According to the improved concept, the on-load tap-changer 1 comprises a selector 3 with at least a first fixed contact 23.1 and a second fixed contact 23.2, each of which can be connected to a winding tap N 1 , ..., NJ , ..., NN of the tapped transformer 2. The total number of fixed contacts depends on the number of winding taps N 1 , ..., NJ , ..., NN. Furthermore, the on-load tap-changer 1 has a first movable selector contact 24.1 and a second movable selector contact 24.2, each of which can contact the individual fixed contacts 23.1, 23.2 of the regulating winding 25. The on-load tap-changer 1 also comprises a load diverter switch 4 with a first load branch 5.1 and a second load branch 5.2. According to this exemplary embodiment, the first load branch 5.1 connects the first fixed contact 23.1 via a series circuit comprising a first vacuum interrupter 6.1 and a second vacuum interrupter 6.2 to the load terminal 8, and the second load branch 5.2 connects the second fixed contact 23.2 via a series circuit comprising a first vacuum interrupter 7.1 and a second vacuum interrupter 7.2 to the load terminal 8. A switching resistor 9.1 or 9.2 is connected in parallel to the first vacuum interrupter 6.1 or 7.1. A first mechanical switching element 18.1 is arranged between the second vacuum interrupter 6.2 and the load terminal 8, and a second mechanical switching element 18.2 is arranged between the second vacuum interrupter 7.2 and the load terminal 8. A first line 10.1 electrically connects the first vacuum interrupter 6.1 and the second vacuum interrupter 6.2 to one another, and a second line 10.2 electrically connects the first vacuum interrupter 7.1 and the second vacuum interrupter 7.2 to one another.Furthermore, a third line 10.3 connects the second vacuum interrupter 6.2 to the first mechanical switching element 18.1, and a fourth line 10.4 connects the second vacuum interrupter 7.2 to the second mechanical switching element 18.2. An additional permanent main contact 19.1, 19.2 is arranged parallel to each load branch 5.1, 5.2. Figure 2 shows the on-load tap-changer 1 in a stationary state, in which at least a part of the load current flows from the winding tap via the first fixed contact 23.1 to the load derivation 8 via the permanent main contact 19.1, in particular a larger part than via the load branch 5.1.

[0033] In the Figures 4a to 4e an exemplary switching sequence of the on-load tap-changer 1 according to the improved concept is described, wherein switching takes place from the second fixed contact 23.2 to the first fixed contact 23.1, or the corresponding winding taps N 1 , ..., NJ , ..., NN of the tapped transformer 2.

[0034] In a step a (cf. Fig. 4a ), the permanent main contact 19.2 is closed or remains closed. The on-load tap-changer 1 is in the stationary state, in which at least a portion of the load current flows from the corresponding winding tap N J+1 via the permanent main contact 19.2 via the second fixed contact 23.2 to the load terminal 8, in particular a larger portion than via the load branch 5.2.

[0035] In a step b (cf. Fig. 4b ), the permanent main contact 19.2 is opened and the first mechanical switching contact 18.1 is closed. The current now flows via the first vacuum interrupter 7.1 of the second load branch 5.2, the second line 10.2, the second vacuum interrupter 7.2 of the second load branch 5.2, the fourth line 10.4, and the second mechanical switching contact 18.2 to the load shunt 8.

[0036] In a step c (cf. Fig. 4c), the first vacuum interrupter 7.1 of the second load branch 5.2 is opened. During the opening process, the second vacuum interrupter 7.2, the fourth line 10.4 and the second mechanical switching contact 18.2 are current-carrying and are spatially outside the defined area 14 (see e.g. Figures 6-8 ) of the vacuum interrupter 7.1. The current then flows from the fixed contact 23.2 via the switching resistor 9.2, the second vacuum interrupter 7.2, the fourth line 10.4, and the second mechanical switching contact 18.2 to the load terminal 8.

[0037] In a step d (cf. Fig. 4d ), the second vacuum interrupter 6.2 of the first load branch 5.1 is closed. The load current is now divided between the first load branch 5.1 and the second load branch 5.2. A circulating current is also superimposed.

[0038] In a step e (cf. Fig. 4e), the second vacuum interrupter 7.2 of the second load branch 5.2 is opened. During the opening process, the second vacuum interrupter 6.2 of the first load branch 5.1, the first mechanical switching element 18.1 of the first load branch 5.1, the second mechanical switching element 18.2 of the second load branch 5.2 and the connecting lines 27 to the switching resistors 9.1 and 9.2 of the first load branch 5.1 and the second load branch 5.2 carry current and are spatially outside the defined area 14 (see e.g. Figures 6-8 ) of the vacuum interrupter 7.2 of the second load branch 5.2. The current then flows from the fixed contact 23.1 via the switching resistor 9.1, the second vacuum interrupter 6.2 of the first load branch 5.1, the third line 10.3, and the first mechanical switching contact 18.1 to the load terminal 8.

[0039] In a step f (cf. Fig. 4f), the first vacuum interrupter 6.1 of the first load branch 5.1 is closed. The current now flows via the first vacuum interrupter 6.1, the first line 10.1, the second vacuum interrupter 6.2, the third line 10.3, and the first mechanical switching contact 18.1 to the load shunt 8.

[0040] In a step g (cf. Fig. 3 ), the permanent main contact 19.1 in the first load branch 5.1 is closed and the second mechanical switching contact 18.2 in the second load branch 5.2 is opened. The on-load tap-changer 1 is again in the stationary state, as in Fig. 3 presented and explained.

[0041] Figures 5 and 6each show an exemplary embodiment of a diverter switch 4 according to the improved concept, wherein, for the sake of clarity, the diverter switch 4 is shown from two different side perspectives. The four vacuum interrupters 6.1, 6.2, 7.1, 7.2 are arranged in a circle around a switching shaft 20 and each have a movable contact 11 and a fixed contact 12. The vacuum interrupters 6.1 and 6.2 are electrically connected to one another via the first electrical line 10.1, and the vacuum interrupters 7.1 and 7.2 are electrically connected to one another via the second electrical line 10.2. The electrically conductive connection is realized via connecting elements 17, which are designed, for example, as a screw and / or stranded wire. The first end of the first electrical line 10.1 is connected to the movable contact 11 of the vacuum interrupter 6 via a connecting element 17.1 and the second end is electrically connected to the fixed contact 12 of the vacuum interrupter 6.2 via a connecting element 17. The first end of the second line 10.2 is electrically connected to the movable contact 11 of the vacuum interrupter 7.1 via a connecting element 17 and the second end is electrically connected to the fixed contact 12 of the vacuum interrupter 7.2 via a connecting element 17. The movable contact 11 and the fixed contact 12 of each vacuum interrupter 6.1, 6.2, 7.1, 7.2 touch each other at at least one point 13 when the vacuum interrupter is closed. Starting from the respective contact point 13, each vacuum interrupter 6.1, 6.2, 7.1, 7.2 each defines a spherical region 14. For the sake of clarity, the contacts 11 and 12, the contact point 13 of which is in the . Figures 4 and 5 only shown on a few vacuum interrupters and provided with a reference symbol.

[0042] Figures 7 and 8each show an exemplary embodiment of the diverter switch in a plan view. The diverter switch 4 has a housing 29 in which the vacuum interrupters 6.1, 6.2, 7.1, and 7.2 are arranged. The housing 29 is essentially cylindrical and made of a GRP plastic. The vacuum interrupters 6.1 and 6.2 are arranged in the housing 29 as mirror images of the vacuum interrupters 7.1 and 7.2. For example, the vacuum interrupter 7.2 is arranged opposite the vacuum interrupter 6.1, and the vacuum interrupter 7.1 is arranged opposite the vacuum interrupter 6.2. This generates the greatest possible distance between the vacuum interrupters 6.1 and 7.1 and the vacuum interrupters 6.2 and 7.2. Between the vacuum interrupters 6.1 and 6.2 of the first load branch 5.1, as well as the vacuum interrupters 7.1 and 7.2 of the second load branch 5.2, there is a first mechanical switching contact 18.1 and 18.2 respectively, also mirror-inverted to each other.second mechanical switching contact 18.2 is arranged. In . Figure 7 It is shown that the second line 10.2 and the second vacuum interrupter 7.2 of the second load branch 5.2 are arranged outside the defined area 14 of the first vacuum interrupter 7.1 of the second load branch 5.2. In Figure 8 It is also shown that the second vacuum interrupter 6.2 of the first load branch 5.1 lies outside the defined area 14 of the second vacuum interrupter 7.2 of the second load branch 5.2. REFERENCE SYMBOL

[0043] 1 On-load tap-changer 2 Tap-changer 3 Selector 4 Diverter switch 5.1 First load branch 5.2 Second load branch 6.1 First vacuum interrupter of the first load branch 6.2 Second vacuum interrupter of the first load branch 7.1 First vacuum interrupter of the second load branch 7.2 Second vacuum interrupter of the second load branch 8 Load shunt 9.1, 9.2 Transfer resistors 10.1 First line 10.2 Second line 11 Moving contact 12 Fixed contact 13 Center point / contact point 14 Defined area 15.1, 15.2 First end 16.1, 16.2 Second end 17 Connecting element 18.1 First mechanical switching contact 18.2 Second mechanical switching contact 19.1, 19.2 Permanent main contacts 20 Switching shaft 21 Axle 22 Motor 23.1, 23.2Fixed contacts Selector 24.1, 24.2Movable selector contacts 25Control winding 27Connecting cable 29Housing (N 1 , ..., NJ , ..., NN )Winding taps

Claims

1. On-load tap-changer (1) for uninterrupted advanced retard switch between winding taps (N1, ...NJ, ..., NN) of a tap-change transformer (2), comprising: - a change-over selector (3) for powerless preselection to a selected winding tap (NJ) ; - a diverter switch (4) for the actual diverter switch operation from the previous winding tap (NJ-1) to the preselected winding tap (NJ) , the diverter switch (4) having a first load branch (5.1) and a second load branch (5.2); - the first load branch (5.1) of the diverter switch (4) comprises a first vacuum interrupter (6.1) and a second vacuum interrupter (6.2), - the second load branch (5.2) of the diverter switch (4) comprises a first vacuum interrupter (7.1) and a second vacuum interrupter (7.2), wherein - each vacuum interrupter (6.1, 6.2, 7.1, 7.2) has a moving contact (11) and a fixed contact (12), and - each vacuum interrupter (6.1, 6.2, 7.1, 7.2) can assume an open state (31), in which the moving contact (11) and the fixed contact (12) do not touch each other, and a closed state, in which the moving contact (11) and the fixed contact (12) touch each other at at least one contact point (13), wherein - a spherical region (14) is defined by the contact point (13) of the fixed contact (12) and the moving contact (11) of each vacuum interrupter (6.1, 6.2, 7.1, 7.2); and - the vacuum interrupters (6.1, 6.2, 7.1, 7.2) of the diverter switch (4) are arranged in such a way that current-carrying parts of the diverter switch (4) are arranged outside the defined area (14), - the first load branch (5.1) electrically connects a winding tap (NJ) via a series connection of the first vacuum interrupter (6.1) and the second vacuum interrupter (6.2) of the first load branch (5.1) to a load leakage line (8), - the second load branch (5.2) electrically connects a respective winding tap (NJ+1) to the load leakage (8) via a series connection of the first vacuum interrupter (7.1) and the second vacuum interrupter (7.2) of the second load branch (5.2), characterized in that - a first mechanical switching contact (18.1) is arranged between the second vacuum interrupter (6.2) of the first load branch (5.1) and the load arrester (8); and - a second mechanical switching contact (18.2) is arranged between the second vacuum interrupter (7.2) of the second load branch (5.2) and the load arrester (8); - the spherical region (14) around the point of contact (13) has a radius of at least 80 mm and at most 200 mm.

2. On-load tap-changer according to claim 1, wherein - current-carrying parts of the diverter switch (4) are a first electrical line (10.1) of the first load branch (5.1) or a second electrical line (10.2) of the second load branch (5.2) or electrically conductive connecting elements (17) or the first mechanical switching contact (18.1) or the second mechanical switching contact (18.2), which are arranged outside the spherical region (14) of each vacuum interrupter (6.1, 6.2, 7.1, 7.2).

3. The on-load tap-changer according to any one of the preceding claims 1-2, wherein - at least the second line (10.2), the second vacuum interrupter (7.2) of the second load branch (5.2) and a fourth line (10.4) are arranged outside the defined area (14) of the first vacuum interrupter (7.1) of the second load branch (5.2).

4. On-load tap-changer according to any one of the preceding claims 1-2, wherein - at least the second vacuum interrupter (6.2) of the first load branch (5.1), a third line (10.3) and the fourth line (10.4) are arranged outside the defined area (14) of the second vacuum interrupter (7.2) of the second load branch (5.2).

5. On-load tap-changer according to claim 2, wherein - the mechanical main switching contacts (18.1, 18.2) are designed as disconnecting switches.

6. On-load tap-changer according to one of the preceding claims, wherein - in the first load branch (5.1), the first vacuum interrupter (6.1) and the second vacuum interrupter (6.2) are electrically connected to one another via the first electrical line (10.1) and the second vacuum interrupter (6.2) and the first mechanical switching contact (18.1) are electrically connected to one another via the third electrical line (10.3), - in the second load branch (5.2), the first vacuum interrupter (7.1) and the second vacuum interrupter (7.2) are electrically connected to one another via the second electrical line (10.2) and the second vacuum interrupter (7.2) and the first mechanical switching contact (18.2) are electrically connected to one another via the fourth electrical line (10.4).

7. The on-load tap-changer according to claim 6, wherein - the electrical lines (10.1, 10.2, 10.3, 10.4) are each electrically conductively connected to the vacuum interrupters (6.1, 6.2, 7.1, 7.2) via connecting elements (17).

8. On-load tap-changer according to one of the preceding claims, wherein - an additional main contact (19.1, 19.2) is provided parallel to each load branch (5.1, 5.2), which in stationary operation takes over at least part of the continuous current conduction and is directly electrically conductively connected to the load feeder (8).

9. On-load tap-changer according to one of the preceding claims, wherein - the vacuum interrupters (6.1, 6.2, 7.1, 7.2) are arranged in a circle around a switching shaft (20).

10. On-load tap-changer according to one of the preceding claims, wherein - the first and the second mechanical main switching contacts (18.1, 18.2) are arranged in mirror image to an axis (21) of the switching shaft (20).

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