EP0640241B1 - Step switch - Google Patents

Abstract

PCT No. PCT/EP93/01114 Sec. 371 Date Sep. 27, 1994 Sec. 102(e) Date Sep. 27, 1994 PCT Filed May 6, 1993 PCT Pub. No. WO93/23861 PCT Pub. Date Nov. 25, 1993.A cast-resin transformer has a transformer housing, a plurality of windings each having a plurality of taps, respective contacts connected to the taps and mounted on the housing in respective arrays which are all identical, and respective identical mounting elements on the housing at each of the contact arrays. Respective identical step switches each serve a respective winding of the transformer and each have a switch housing secured to the respective mounting element of the transformer housing at the respective contact array and a step contact movable along the respective connector elements and electrically engageable therewith. A drive motor and a main shaft are connected to all of the step contacts for synchronously stepping the step contacts along the respective connector elements.

Description

The invention relates to a tap changer with a tap transformer according to the preamble of patent claim 1.
Such tap changers with a tap changer are known from Siemens magazine 50 (1976) number 1, pages 9 to 17, "oven transformers ...", article by Robert Brehler.

From DE-PS 36 30 415 it is especially known for cast resin transformers to provide at least one of these single-phase tap changer modules in a conventional, oil-filled design, which is attached to a bracket laterally next to the transformer and is electrically connected to it by connecting lines.

From CH-PS 391 088 an arrangement has also become known in which the connections are led out of the transformer and lead to contacts which are arranged in a ring on the circumference of a cylindrical housing into which a step switch can be lowered, as a result of which this is achieved by corresponding contacts on the outer casing of the tap changer housing can be electrically connected to the wreath-like contacts and thus to the transformer.

From DE-OS 27 12 484 an add-on stage switch of the load selector type for oil transformers is also known, which has a slatted structure which fixes and guides the connecting lines between the stage contacts and the associated transformer.

Finally, Japanese utility model Sho-62-10973 describes a cast resin transformer in which the connections of the step windings to a cast one Contact plate are guided in the form of a connection terminal, from where they can be guided to a tap changer by means of electrical connecting lines.

All of these known arrangements have several serious disadvantages.
On the one hand, a large number of electrical connections on the tap changer must be connected to the respective taps of the tap windings on the transformer using numerous electrical cables. This is complex, requires special means for mechanically fixing these lines and to avoid mutual electrical interference and, moreover, does not rule out a mix-up of the connections, for example during assembly or after revisions. Furthermore, it is disadvantageous that the tap changers to be assigned are not specifically designed for specific transformers and must be fastened in the vicinity of the transformer by means of special holding means, crossbars, brackets or the like which are not provided per se on the transformers and are not required . This also means that the respective tap changer does not only depend on the electrical characteristics of the transformer, its number of steps, etc., but also on the respective mechanical and structural conditions, such as size, shape, type and position of the electrical connections and the mechanical fasteners and the like have to be adjusted. This leads to an undesirable variety of tap changers to be provided.

The object of the invention is to provide a tap changer of the add-on type of uniform design which can be electrically connected in a simple manner to mechanically insulated tap transformers of different types and construction, and mechanically fastened to them. According to the invention, this is solved by the technical features of claim 1.

The subclaims contain advantageous developments of the invention.

Numerous advantages are achieved by this invention. On the one hand, the line connections customary according to the prior art with all their known problems, confusion possibilities and the like are eliminated, since the tap changer according to the invention is directly connected to each a step winding of the transformer can be attached. On the other hand, this direct fastening of the tap changer and the fact that the electrical connections as well as the mechanical fastening means are in a uniform spatial connection mean that expensive fastening devices, brackets, trusses and the like can be dispensed with.
Configurations are easily possible due to the corresponding quasi "interfaces" on both the step transformer and the switch. The technical implementation of the tap changer using single-phase tap changer modules has the advantage of being largely standardized.

The tap changer modules have uniform connection elements and fastening means, by means of which they can be connected directly to connection and contact means on the cast resin transformer. In a particularly advantageous manner, the housings of the tap changer modules each have at least one cutout through which, in the assembled state, the connection and contact means of the transformer extend into the interior of the respective tap changer module and can be directly connected by it by forming the actual tap changer contacts. For this purpose, these connection elements are preferably electrode-like at their free end and arranged in a circle or spatially to one another along a line.

In a continuation of the invention, it can be advantageous to electrically and the tap changer modules via contact and / or fastening adapters with the respective tap transformers connect mechanically. In this way, no change to the tap changer modules themselves is required to adapt to changed connection and fastening conditions, but only much simpler different adapters are required.

Fig. 1

zeigt die Anordnung eines erfindungsgemäßen modularen Stufenschalters mit einem Stufentransformator in Gießharzausführung in schematischer Darstellung

Fig. 1a

zeigt eine alternative mögliche Anordnung

Fig. 2

zeigt die zusammenwirkenden Verbindungs- und Befestigungselemente in perspektivischer Darstellung

Fig. 3

zeigt eine zweite Ausführung dieser Elemente ebenfalls in perspektivischer Darstellung

Fig. 4

zeigt eine dritte Ausführung dieser Elemente wiederum in perspektivischer Darstellung

Fig. 5

zeigt einen erfindungsgemäßen modularen Stufenschalter in einer weiteren Ausführung in Schnittdarstellung von oben

Fig. 6

zeigt ein diesem Stufenschalter zugrundeliegendes mögliches Schaltschema.

The invention will be explained in more detail below with reference to drawings.

Fig. 1

shows the arrangement of a modular tap changer according to the invention with a tap transformer in cast resin design in a schematic representation

Fig. 1a

shows an alternative possible arrangement

Fig. 2

shows the interacting fasteners and fasteners in perspective

Fig. 3

shows a second embodiment of these elements also in perspective

Fig. 4

shows a third embodiment of these elements again in perspective

Fig. 5

shows a modular tap changer according to the invention in a further embodiment in a sectional view from above

Fig. 6

shows a possible circuit diagram on which this tap changer is based.

A three-phase step transformer gate 1, which is designed as a cast resin transformer, has a connection terminal 2.1, 2.2, 2.3 for each phase. These connection terminals 2.1, 2.2, 2.3 each have the same geometric assignment of electrical connection elements 2.1.1, 2.2.1 and 2.3.1, which are each connected to the corresponding taps of the step winding of the respective phase. They also have mechanical fasteners 2.1.2, 2.2.2 and 2.3.2. With each connection terminal there is a single-phase, identical step switch module 3.1, 3.2 and 3.3. electrically and mechanically connected. The connection is made through corresponding electrical connection elements 3.1.1, 3.2.1 and 3.3.1 arranged on the respective tap changer module and corresponding mechanical fastening means 3.1.2, 3.2.2 and 3.3.2.
The synchronous actuation of the tap changer modules is carried out by drive shafts 4.1, 4.2, 4.3, which are connected to a common motor drive 5. 1a schematically shows a further exemplary possibility of arranging the drive shafts.

2 shows a connection terminal 2.1 of the step transformer 1 and a step switch module 3.1 connected thereto. A plurality of connection elements 2.1.1, each of which corresponds to a tap of the step winding, are arranged vertically one above the other in a plug-like design; Fasteners 2.1.2, for example stud bolts, are arranged on either side of this. The step switch module 3.1 has geometrically corresponding electrical connection elements 3.1.1, designed as contact sockets or clamps, which enclose the connection elements 2.1.1, and corresponding fastening means 3.1.2, in this case bores in a flange, so that the step switch module 3.1 by means of Nuts can be screwed to the respective connection terminal 2.1.1. The corresponding constructive design of the respective pairings of electrical connection elements and mechanical connecting means can be varied depending on the respective electrical requirements and loads and the mechanical and in particular also spatial conditions. In any case, it is ensured that only a single tap changer module is required, regardless of the number of phases of the transformer. Each tap changer module corresponds to a complete single-phase tap changer, and in particular also has its own energy accumulator for rapid triggering. Such step switch modules are particularly advantageous as single-phase load selectors, which are particularly space-saving due to the combination of step selection and uninterrupted load switching are producible. Furthermore, it is of course particularly advantageous to also provide the tap changer modules in dry construction, since this eliminates the need for a separate, otherwise necessary, sealing of the oil space. Finally, it is also possible to design the tap changer modules as power-free changeover switches, for example linear changeover switches, which further simplifies the entire arrangement since, inter alia, the energy store is dispensed with, but on the other hand it is necessary to switch off the transformer before switching from one step to another.

It is also advantageous to design the electrical connection elements on the connection terminal in such a way that they extend into the interior of the connected tap changer module and are used there directly as contacts between which the switchover takes place, that is to say they are connected.
Such an arrangement is shown in FIG. 3. In this case, when the connection terminal 2.1 is unchanged from FIG. 2, the electrical connection elements 2.1.1, which are also arranged one above the other, are designed like electrodes at their free ends. The tap changer module 3.1 fastened to the connection terminal 2.1 does have corresponding fastening means 3.1.2, but there are no separate electrical connection elements.
Rather, there is a recess 3.4 in the housing of the tap changer module 3.1, which faces the connection terminal 2.1 and through which the electrode-like free ends of the electrical connection elements 2.1.1 extend into the interior of the tap changer module 3.1 and there directly the fixed, appropriately wired tap contacts of the Form tap changer on which at least one movable tap selector and / or load selector contact 3.5 runs.
3a shows an alternative arrangement of the electrical connection elements; this circular arrangement is also suitable for directly forming the fixed step contacts, which can then be connected in a manner known per se by a centrally mounted, rotatable contact bridge.

Fig. 4 shows a further embodiment. Here, too, the tap changer module 3.1 has a cutout 3.4 which faces the connection terminal 2.1. In a modification of the invention, however, the electrical rejections are formed only as cast-in threaded sleeves 6.1.1 ... 6.5.2, with two electrical sleeves 6.n.1 and 6.n.2 corresponding to each other corresponding to each electrical connection. Molded parts 7.1 ... 7.5, which are screwed together with the threaded sleeves lying next to each other in pairs, form both the stepped contacts 7.1.1 ... 7.1.5 to be connected by the movable contact 3.5, and at the same time, fastening tabs 7.2.1 ... 7.2 .5 the respective tap changer module is attached to the molded parts 7.1 ... 7.5. So electrical connection elements and mechanical fasteners are combined.

5 shows a single-phase tap changer according to the invention from above. A cast resin transformer has, on the front of each winding 8, mutually arranged contact sockets 9, each of which is connected to a lead-out of the step winding, as has already been explained above. In the present example, two threaded bushings 9 of the same potential lie horizontally next to one another and are bolted by bolts 10 to the stepped contact 11, which is designed as a molded piece, directly or via a further conductive adapter 12. Each of the identically designed tap contacts 11 arranged one below the other on a vertical line has two parallel contact cheeks 11.1 and 11.2 which extend parallel to one another into the interior of the housing of the tap changer.
The two contact cheeks 11.1 and 11.2 are screwed to two housing parts 13.1, 13.2 arranged symmetrically from above; these form the housing of the tap changer with two cover plates 14.1, 14.2, for example made of insulating material, and two horizontal guide bolts 15. With this design, the rear side of the housing facing away from the fixed contacts remains open; it is of course also possible instead of parallel horizontal spacer 15 to provide a closed end plate or the like ..
At least one, here two, curved rails 16.1 and 16.2, at least one, here two, guide rails 17.1 and 17.2 and at least one discharge rail 18 are arranged between the horizontal spacer bolts 15, running vertically and parallel to one another.
In addition, attached to cantilevers, not shown, within the housing - also running vertically through this - a further contact rail 19 is arranged, which is connected to the diverter rail 18 via a switching resistor R, not shown, and a switch 20.

FIG. 6 shows the circuit diagram of such a tap changer according to FIG. 5.
A drive shaft 26, which is inserted into the housing from above and has a threaded spindle, both vertically actuates a first contact bridge 21, which in each case sweeps over a contact cheek 11.2 of a fixed step contact 11, and an energy storage 22, which is only indicated, in a vertical direction , which depends on the direction of rotation of the drive shaft 26, excited. It is triggered by spring-loaded pawls, which are known per se and which are actuated by the cam rails 16.1, 16.2. In its sudden vertical movement, in which it runs after the first contact bridge 21, the force accumulator 22, which carries a second contact bridge 23, is mechanically guided by the guide rails 17.1 and 17.2. The second contact bridge 23 connects the other contact cheek 11.1 of the fixed step contact 11 via a second switch 24 to the load conductor 18, expediently by means of a further contact bridge 25.
Vacuum switches are advantageously used as switches 20 and 24, and their switching actuation can also be controlled by the contour of the curved rails 16.1 and 16.2 which are present anyway.

Claims (10)

1. Tap selector switch of the attachment type at a tapped transformer (1), preferably a cast-resin-insulated tapped transformer, wherein this tapped transformer at its outward side displays electrical connecting elements (2.1.1, 2.2.1, 2.3.1), which are each electrically connected with a respective winding output line of a tap winding, wherein this tapped transformer furthermore at its outward side displays at least one mechanical fastening means (2.1.2, 2.2.2, 2.3.2), which corresponds with at least one fastening means (3.1.2, 3.2.2, 3.3.2) of the tap selector switch, wherein the tap selector switch consists of identical single-phase tap selector switch modules (3.1, 3.2, 3.3), which display all means required for the load output and each have an individual housing at least partially enclosing these means and wherein the tap selector switch modules (3.1, 3.2, 3.3) each stand in connection with a motor drive (5) by way of a respective drive shaft (4.1, 4.2, 4.3), characterised thereby, that the electrical connecting elements (2.1.1, 2.2.1, 2.3.1) of the tapped transformers (1) are wirable as fixed tap contacts in the interior of the housing of each tap selector switch module (3.1, 3.2, 3.3) without interconnection of a connecting line between the tapped transformer (1) and the respective tap selector switch module (3.1, 3.2, 3.3).
2. Tap selector switch according to claim 1, characterised thereby, that the electrical connecting elements (2.1.1, 2.2.1, 2.3.1) of the tapped transformer (1) are constructed as electrode connections which project through at least one opening into the interior of the respective tap selector switch module (3.1, 3.2, 3.3) and there themselves form the fixed tap contacts.
3. Tap selector switch according to claim 1 or 2, characterised thereby, that the mechanical fastening means (3.1.2, 3.2.2, 3.3.2,; 7.2.1 to 7.2.5) as well as also the electrical fastening elements (2.1.1, 2.2.1, 2.3.1; 7.1.1 to 7.1.5) are formed by electrically conductive shaped parts (7).
4. Tap selector switch according to claim 3, characterised thereby, that the housing of vertically arranged shaped parts (11) itself consists of housing parts (13.1, 13.2), which are connected with these and extend away laterally from the tapped transformer (1), and of two substantially parallel cover plates (14.1, 14.2), which are in turn connected with these housing parts as well as of at least two horizontal guide pins (15), which are disposed between the cover plates (14.1, 14.2) and fix them in their position at that side of the housing, which is remote from the shaped parts (11), that at least one guide rail (17.1, 17.2), at least one cam rail (16.1, 16.2) and at least one output rail (18) are disposed vertically between the guide pins (15), that a force storage device (22), which is tensionable vertically by a drive shaft (26) and releasable by pawls which are actuable by the at least one cam rail (16.1, 16.2), is guidable by the at least one guide rail (17.1, 17.2), that each fixed tap contact (11) is connectable by a first contact bridge (21), which is actuable directly by the drive shaft (26), with a further contact rail (19), which extends vertically in the housing and is connectable by way of a circulating-current-limiting resistance (17) and a first switch (20) with the load output rail (18), and that each fixed tap contact (11) is likewise connectable by a further contact bridge (23), which is actuable by the released force storage device (22), by way of at least one further switch (24) with the load output rail (18).
5. Tap selector switch according to one of the claims 1 to 4, characterised thereby, that each fixed tap contact (11) displays two parallel contact cheeks (11.1, 11.2), which extend each parallelly to the other into the interior of the housing in such a manner that one contact cheek (11.2) is wipable by the first contact bridge (21) and the other contact cheek (11.1) is wipable independently thereof by the further contact bridge (23).
6. Tap selector switch according to one of the claims 4 and 5, characterised thereby, that in place of the guide pins, a closure plate extends vertically between the cover plates and at its inward side carries the guide rails (17.1, 17.2), the cam rails (16.1, 16.2) and the load output rail (18).
7. Tap selector switch according to claim 6, characterised thereby, that the cover plates (14.1, 14.2) consist of insulating material.
8. Tap selector switch according to claim 1, characterised thereby, that the electrical connecting elements (2.1.1, 2.2.1, 2.3.1) of the tapped transformer (1) are connectable by means of an in itself known plug-and-socket connection with the fixed tap contacts in the interior of the housing of each tap selector switch module (3.1, 3.2, 3.3) in such a manner that the plug-and-socket connection itself is formed by the electrical connecting elements (2.1.1, 2.2.1, 2.3.1) of the tapped transformer (1) on the one hand and further electrical connecting elements (3.1.1, 3.2.1, 3.3.1),which are electrically connected with the fixed tap contacts, of the respective tap selector switch module (3.1, 3.2, 3.3).
9. Tap selector switch according to claim 8, characterised thereby, that each tap selector switch module (3.1, 3.2, 3.3) is connected to the tapped transformer (1) by means of an interposed adapter which connects the electrical connecting elements (2.1.1, 2.2.1, 2.3.1) and/or the fastening means (2.1.2, 2.2.2, 2.3.2), which respectively belong together, of the tapped transformer (1) with the electrical connecting elements (3.1.1, 3.2.1, 3.3.1) and/or fastening means (3.1.2, 3.2.2, 3.3.2) of the respective tap selector switch module (3.1, 3.2, 3.3).
10. Tap selector switch according to claim 8 or 9, characterised thereby, that the electrical connecting elements (3.1.1, 3.2.1, 3.3.1) are at the same time also the mechanical fastening means (3.1.2, 3.2.2, 3.3.2).

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