Selector for on-load tap-changer

Abstract

The invention relates to a selector (1) for an on-load tap changer, comprising: a fine selector (2) having at least one selector arm (21, 22); a preselector (4), characterized in that the preselector (4) is actuated via at least one selector arm (21, 22) of the fine selector (2).

Description

Technical Field

[0001] The invention relates to a selector for an on-load tap changer for interruption-free load switching between different winding taps of a tapped transformer. Background Art

[0002] US Pat. No. 3,155,782 discloses an on-load tap changer with a selector. The selector comprises a fine selector and a preselector. Both the fine selector and the preselector arms are actuated by separate transmission mechanisms. This design requires that all preselector components, such as the fixed and movable contacts, be located outside the transmission mechanism. This, in turn, is detrimental to the insulation distance of the entire switch, as the preselector contacts are located further away from the windings. Furthermore, many transmission mechanisms are complex and expensive. Summary of the Invention

[0003] The object of the present invention is to provide a selector for an on-load tap changer which is of simple and compact construction and which nevertheless offers a high degree of safety.

[0004] According to a first aspect, the present invention provides a selector for an on-load tap changer, comprising a fine selector having at least one selector arm, and a preselector, the preselector being actuated via the selector arm of the fine selector.

[0005] By operating the preselector via the selector arm, the transmission mechanism required for its operation is superfluous. Therefore, the operation is performed indirectly via the transmission mechanism of the fine selector. Furthermore, various parts of the preselector, such as the contacts, are located near the selector contacts and, therefore, close to the parts that carry the voltage, namely the winding taps. This makes it possible to shield both the fine selector and the preselector from the transmission mechanism using insulating plates. This makes the selector not only more reliable but also smaller, which also has a cost-effective effect.

[0006] The fine selector can be designed in any desired manner as required and can, for example, comprise a first selector arm and a second selector arm. One of the selector arms can comprise a rocker arm.

[0007] The preselector can be designed in any desired manner as required and can, for example, comprise a preselector arm having a first end and a second end. The preselector arm can have a guide at its second end.

[0008] The preselector may be actuated indirectly or directly via one of the selector arms.

[0009] It may be provided that:

[0010] The rocker arm acts on the second end of the preselector arm when the preselector is actuated;

[0011] The rocker arm has a roller;

[0012] The preselector arm has a guide device on its second end;

[0013] When the preselector is actuated, the roller temporarily engages in the guide and the preselector arm is pivoted.

[0014] The guide device can be designed in any desired manner as required and can be designed, for example, as a groove, a slot or a partially slotted groove.

[0015] It can be provided that the preselector arm is pivoted about a rotation point on the second axis.

[0016] It may be provided that the first selector arm and the second selector arm are rotatably mounted on a first shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention and its advantages are described in more detail below with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of a tapped transformer known from the prior art is shown;

[0019] Figure 2 and Figure 3 A first embodiment of a selector according to the invention is shown. DETAILED DESCRIPTION

[0020] Identical or identically functioning elements of the present invention are designated by the same reference numerals. For the sake of clarity, only those reference numerals are shown in the respective figures that are necessary for describing the respective figure. The illustrated embodiments merely serve as examples of how the selector according to the present invention may be configured and therefore do not constitute a definitive definition of the present invention.

[0021] Figure 1 A schematic diagram of a tap-changer known from the prior art with an on-load tap changer is shown. The tap-changer has at least one main winding 60 and a regulating winding 61. The main winding 60 is connected at one end to a preselector 4. The preselector 4 connects the main winding 60 to the upper or lower end of the regulating winding 61. The regulating winding 61 has a plurality of winding taps 62. The winding taps 62 are contacted via the selector arms 21 and 22 of the fine selector 2. The fine selector 2 and the preselector 4 form the selector 1. The selector 1 is also connected to the load changeover switch. The selector 1 usually preselects the winding tap 62 to be connected, and the load changeover switch switches from the current winding tap to the preselected winding tap under load.

[0022] Figure 2 and Figure 3The selector 1 according to the present invention is shown. The selector 1 includes a fine selector 2 and a preselector 4. The fine selector 2 includes a first selector arm 21 and a second selector arm 22. The selector arms 21 and 22 are rotatably mounted on a first shaft 25. The first selector arm 21 is located directly behind the second selector arm 22, thus in two planes. A first Maltese wheel 26 is mechanically connected to the first selector arm 21. A second Maltese wheel 27 is mechanically connected to the second selector arm 22. A drive 28 having two drive rollers 29 and 30 drives one of the Maltese wheels 26 and 27 by rotation, and thus drives one of the selector arms 21 and 22. The continuous motion of the drive 28 is converted into a stepping motion by the drive rollers 29 and 30 and the Maltese wheels 26 and 27. Therefore, regardless of the switching direction of the selector 1, one of the selector arms always moves first in one direction of rotation, and then the other selector arm moves in the same direction of rotation. Contact elements 31 are provided on the selector arms 26 , 27 , which contact elements are in contact with corresponding selector contacts 5 . The selector contacts 5 are arranged in a circle or at least in a circle arc in the plate 6 and are connected to winding taps 62 of the regulating winding 61 .

[0023] The preselector 4 of the selector 1 has a preselector arm 40, three contacts 44, 45, 46, and a movable contact unit 43. The contact unit 43 is movably mounted on the first end 41 of the preselector arm 40. The preselector arm 40 is fork-shaped or has a guide 49 at its second end 42. The preselector arm 40 is also rotatably mounted on a second axis 47. The rotation point 48 of the preselector arm 40 is located between the first end 41 and the second end 42 of the preselector arm 40, preferably in its center.

[0024] A rocker arm 23 is arranged on the second selector arm 22. This rocker arm has a roller 32 at its extended end.

[0025] The second end 42 of the preselector arm 40 has a guide 49 designed so that the roller 32 of the rocker arm 23 can engage therein, allowing the preselector arm 40 to pivot about its rotation point 48, while the second selector arm 22 selects and the rocker arm 23 rotates. In this process, the first end 41 of the preselector arm 40 moves from the first position to the second position. The contact unit 43 then no longer connects the first contact 44 to the second contact 45, but instead connects the second contact 45 to the third contact 46. Alternatively, the first end 41 of the preselector arm 40 moves from the second position to the first position. The contact unit 43 then no longer connects the third contact 45 to the second contact 46, but instead connects the second contact 44 to the first contact 45. The preselector arm 40 does not rotate completely, but rather partially. In other words, the preselector arm 40 moves from the first position to the second position and back again, pivoting back and forth, thereby actuating the preselector 4. The main winding 60 is connected to the upper end or the lower end of the regulating winding 61 .

[0026] When and in which direction the preselector arm 40 is deflected is dependent on the second selector arm 22 and thus on the position and direction of rotation of the selector 1 .

[0027] Reference Signs List

[0028] 1 selector

[0029] 2 Fine Selector

[0030] 4 Preselector

[0031] 5 selector contacts

[0032] 6 boards

[0033] 21 First selector arm

[0034] 22 Second selector arm

[0035] 23 rocker arm

[0036] 24 rollers

[0037] 25 First axis

[0038] 26 First Malta

[0039] 27 Second Malta

[0040] 28 Driver

[0041] 29 First drive roller

[0042] 30 Second drive roller

[0043] 31 contact elements

[0044] 32 rollers

[0045] 40 Preselector Arm

[0046] 41 First end of the preselector arm

[0047] 42 Second end of the preselector arm

[0048] 43 contact elements

[0049] 44 First preselector contact

[0050] 45 Second preselector contact

[0051] 46 Third preselector contact

[0052] 47 Second Axis

[0053] 48 rotation points

[0054] 49 Guidance Device

[0055] 60 Main winding

[0056] 61 regulating winding

[0057] 62 winding taps.

Claims

1. A selector (1) for an on-load tap changer, the selector comprising: A fine selector (2) having a first selector arm (21) and a second selector arm (22); Preselector (4), It is characterized in that The preselector (4) is operated via at least one of a first selector arm (21) and a second selector arm (22) of the fine selector (2), The preselector (4) has a preselector arm (40) having a first end (41) and a second end (42); The second selector arm (22) has a rocker arm (23) which acts on the second end (42) of the preselector arm (40) when the preselector (4) is actuated.

2. The selector (1) according to claim 1, wherein The rocker arm (23) has a roller (32); The preselector arm (40) has a guide device (49) at its second end (42); When the preselector (4) is actuated, the roller (32) temporarily engages in the guide (49) and the preselector arm (40) is pivoted.

3. A selector (1) according to claim 2, wherein The guide device (49) is designed as a groove, a slot or a partially slotted groove.

4. The selector (1) according to any one of claims 1 to 3, wherein The preselector arm (40) is pivotable about a rotation point (48) on a second axis (47).

5. The selector (1) according to any one of claims 1 to 3, wherein The first selector arm (21) and the second selector arm (22) are rotatably mounted on a first shaft.

6. On-load tap changer having a selector (1) according to any one of claims 1 to 5.

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