EP3685411B1 - Winding assembly - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to a winding arrangement for a transformer, in particular with an operating voltage of Um ≥ 72.5kV, the winding arrangement having at least one winding that ends in a winding conductor, the winding conductor being connected to a switching line which is used to interconnect the winding with others Windings is formed.

The winding arrangement according to the invention can be used in various types of transformers, in particular in distribution transformers, such as in liquid-filled distribution transformers.

STATE OF THE ART

From the DE 20 2014 105 168 U1 describes a planar winding module for use in planar transformers. A connector is used to interconnect one winding with another winding.

the GB 800 992 A discloses a transformer and a field coil. Here, too, a connector is used to connect two partial windings inside a winding.

Further prior art is in the EP 2 549 494 A1 , the US 2015/206648 A1 , the EP 2 660 832 A2 and the JP 2008 288512 A described.

The person skilled in the art knows from constant practice that in oil-filled distribution transformers for high temperature requirements, e.g. at an operating temperature of more than 105 ° C, aramid insulation is often required for the outlets. With an equipment voltage of Um ≥ 72.5 kV, a high field strength occurs in the high-voltage discharge area, i.e. the high-voltage area. This selective field strength greatly increases the risk of partial discharges and flashovers. In order to reduce this electrical stress in low-temperature applications, a shield is used around the exit to enlarge the conductor. Some of these tried and tested materials for shielding, which have been used for many years, are not available for high-temperature applications.

DISCLOSURE OF THE INVENTION

It is therefore an object of the invention to provide a winding arrangement which overcomes the disadvantages of the prior art and also reduces the risk of partial discharges and flashovers in the high-voltage discharge area for high-temperature applications.

This object is achieved according to the invention by a winding arrangement according to claim 1. Starting from a winding arrangement for a transformer, in particular with an operating medium voltage of Um ≥ 72.5kV, the winding arrangement having at least one winding that is in a winding conductor ends, wherein the winding conductor is connected to a switching line which is designed to interconnect the winding with other windings, it is provided that the connection of the switching line to the winding conductor is arranged inside the winding.

The connection of the winding conductor to the switching line, which generally has a larger conductor cross-section than the winding conductor, inside the winding and the formation of the diversion line with the switching line significantly reduces the electrical field strength at the diversion line.

The fact that the connection of the switching line with the winding conductor is arranged inside the winding means that the connection is surrounded by the winding, seen both in the radial direction of the winding and in the axial direction of the winding. Assuming that the winding is arranged around a winding axis, for example, relative to the winding axis, there is still a part of the winding radially outside the connection according to the invention and also a part of the winding axially before and after the connection. The winding conductors of the winding thus insulate the connection largely, in particular completely, from the space outside the winding.

The invention is advantageously used for the high-voltage winding, that is to say the high-voltage winding, of a transformer.

In order to easily and permanently electrically connect the winding conductor to the switching line, it can be provided that the connection between the switching line and the winding conductor is a crimp connection. A crimp connection is created when two components are connected to one another by plastic deformation, for example by flanging, squeezing, crimping or folding. A crimp connection is not in itself a detachable connection. A crimp connection is form-fitting.

In the case of a crimp connection, a connecting element is generally used, into which one or both conductors to be connected are inserted. The connecting element can be designed as a sleeve or cable lug, for example. In addition to the electrical connection, crimping also creates a mechanical connection between the two conductors to be connected, here the winding conductor and the switching line. Crimping pliers or stop presses, for example, are used as tools for crimping. The shape of the tool and the pressing force must each be adapted in such a way that a form-fitting connection is created, but none of the conductors is destroyed, in particular broken, in the process. As an alternative to crimping, the two conductors can also be soldered or welded.

Since the connection is located within the winding, it is advantageous that the connection element, which establishes the connection between the switching line and the winding conductor, is surrounded by an electrical shield. In this way, the electrical field of the winding is shielded from the switching line in a simple manner.

In particular, it can be provided that the electrical shield also surrounds the part of the winding conductor adjoining the connecting element and the part of the switching line adjoining the connecting element. As a result, good shielding of the connecting element is achieved in any case.

The electrical shield can most simply comprise a conductive layer which surrounds at least the connecting element. Conductive foils, braids or sheets are conceivable here. The conductive layer can contain, for example, copper.

The electrical shielding, the part of the winding conductor adjoining the connecting element and the part of the switching line adjoining the connecting element can be surrounded by a common insulation. As a result, there can be no conductive connection or flashover from the rest of the winding to the switching line.

Assuming that the winding is arranged around a winding axis, then basically three design variants are conceivable, where a connection of a switching line to a winding conductor, in particular the corresponding connecting element, is arranged relative to the winding.

In the first variant it is provided that a part of the winding is still located both radially outside a connection between a switching line and a winding conductor and axially before and after this connection between the switching line and the winding conductor. The connection, in particular in the form of the connecting element, is therefore surrounded in the axial direction on both sides by winding conductors. In the radial direction, further winding conductors or further sections of the same winding conductor are present at least outside the connection, in particular outside the connecting element. An insulation of the winding can be located radially within, for example. This embodiment variant is therefore suitable for the beginning of the winding which, viewed in the radial direction of the winding, lies on the inside.

In the second variant it is provided that a part of the winding is still located both radially within a connection of a switching line to a winding conductor and axially before and after this connection of the switching line to the winding conductor. The connection, in particular in the form of the connecting element, is therefore surrounded in the axial direction on both sides by winding conductors. In the radial direction, further winding conductors or sections of the same winding conductor are present at least within the connection, in particular within the connecting element. An insulation of the winding can be located radially outside, for example. This embodiment variant is therefore suitable for the winding end which, viewed in the radial direction of the winding, is on the outside.

In the third variant it is provided that a part of the winding is still located radially inside, radially outside, axially before and axially after a connection of a switching line to a winding conductor. The connection, in particular in the form of the connecting element, is therefore surrounded on all sides by winding conductors. This variant is suitable for taps which, viewed radially, lie between the start of the winding and the end of the winding.

It is also conceivable that several connections according to the invention are provided per winding. This means that two or all three design variants can also be present on one winding. In particular, there can be several connections of the third variant embodiment.

The invention also comprises a transformer, in particular a power transformer, preferably an oil-filled distribution transformer, with a winding arrangement according to the invention. Power transformers are transformers that are designed for high performance, for example for use in electrical energy networks. Power transformers are often designed as three-phase three-phase AC transformers. Power transformers in the range from a few 10 kVA to a few MVA are used in local transformer stations that serve to supply the low-voltage networks and are known as distribution transformers. They are often filled with liquid, usually oil-filled.

BRIEF DESCRIPTION OF THE FIGURES

• Fig. 1 einen Längsschnitt der erfindungsgemäßen Wicklungsanordnung im Bereich der Verbindung zwischen Schaltleitung und Wicklungsleiter,
• Fig. 2 einen Längsschnitt des Bereichs um die Verbindung zwischen Schaltleitung und Wicklungsleiter aus Fig. 1.

To further explain the invention, reference is made in the following part of the description to the figures, from which further advantageous details and possible areas of application of the invention can be taken. The figures are to be understood as exemplary and are intended to illustrate the character of the invention, but in no way restrict it or reproduce it conclusively. It shows:

• Fig. 1 a longitudinal section of the winding arrangement according to the invention in the area of the connection between switching line and winding conductor,
• Fig. 2 a longitudinal section of the area around the connection between switching line and winding conductor Fig. 1 .

WAYS OF CARRYING OUT THE INVENTION

Fig. 1 shows the upper end of a winding arrangement according to the invention with a winding 1 which is arranged around a winding axis 5. Further windings can also be arranged radially inside and / or outside the winding 1. The winding 1 is usually wound around a core leg, not shown here, of a transformer core and consists of one or more winding conductors 3. The winding conductor 3 can be a winding wire, for example. In order to lead the electrical energy out of the winding 1 and then out of the transformer housing that surrounds the windings 1, or in order to introduce the electrical energy from the outside through the transformer housing into the winding 1, a so-called discharge is provided, i.e. a conductive connection, which connects the end of the winding conductor 3 of the winding 1 through the transformer housing with a line outside the transformer.

The diversion also includes so-called switching lines 2, by means of which the individual windings 1 of the transformer can be connected to one another while still inside the transformer housing. In this way, the three phases of a three-phase AC transformer can be interconnected.

The winding 1 ends in a winding conductor 3 and is connected by means of a connecting element 4 to a switching line 2, which is used to interconnect the winding 1 with other windings. The connecting element 4 is arranged in the interior of the winding. This means, on the one hand, that part of the winding 1 is still located in the radial direction of the winding 1, i.e. normal to the winding axis 5, at least outside the connecting element 4, here the majority of the winding 1. The end of the winding conductor 3 forms here the beginning of the winding of winding 1, which is designed here as a high-voltage winding. The beginning of the winding and thus the connecting element 4 lies here - viewed in the radial direction - on the inside on the insulation of the winding 1 from the main scattering gap, and this in turn lies between the high-voltage winding and the low-voltage winding.

Inside the winding also means that part of the winding 1 is still located in the direction parallel to the winding axis 5 before and after the connecting element 4. In Fig. 1 further winding conductors of the winding 1 are also located above and below the connecting element 4. These further winding conductors of the winding 1 thus isolate the connecting element 4 from the space outside the winding 1.

The arrangement of the connection, namely the connection element 4 here, corresponds to FIG Fig. 1 the previously described first variant for the beginning of the winding. The connecting element 4 could, however, according to the second variant, also be used for the winding end that is on the outside in the radial direction of the winding 1, see the alternative position 9 of the connecting element 4 drawn as a vertical line. The connecting element 4 would then be radially outside, for example Surrounded only by the insulation of the winding 1, on all other sides (radially inside, axially) by the winding conductors of the winding 1. The connecting element 4 could, however, also be used for a tap in the radial direction of the winding 1 according to the third embodiment variant lies somewhere between the beginning of the winding and the end of the winding, see the exemplary alternative position 8 of the connecting element 4 drawn as a vertical line. The connecting element 4 would then be surrounded on all sides by winding conductors of winding 1.

Because the switching line 2 has a larger conductor cross-section than the winding conductor 3, the electric field strength outside of the winding 2 is lower on the outside of the switching line 2 than in the winding conductor 3, if this instead of the switching line 2 from the winding 1 - in Fig. 1 up from winding 1 - would be led out.

In Fig. 2 the connecting element and - partially in sectional view - its immediate surroundings are shown enlarged. Both the switching line 2 and the winding conductor 3, which has a smaller cross section than the switching line 2, are routed into the connecting element 4 and are connected to one another in a mechanically and electrically conductive manner by means of a crimp connection. An electrical shield 6 surrounds the connecting element 4, the part of the winding conductor 3 adjoining the connecting element 4 and the part of the switching line 2 adjoining the connecting element 4 Fig. 1 ) and beyond that, an insulation 7 is provided which surrounds the electrical shield 6, the part of the winding conductor 3 adjoining the connecting element 4 and the part of the switching line 2 adjoining the connecting element 4.

List of reference symbols:

1

Winding

2

Switching line

3

Winding conductor

4th

Connecting element

5

Winding axis

6th

electrical shielding

7th

insulation

8th

alternative position of the connecting element 4

9

alternative position of the connecting element 4

Claims (10)

1. Winding assembly for a transformer, in particular having a medium operating voltage of Um ≥ 72.5kV, wherein the winding assembly has at least one winding (1) which ends in a winding conductor (3), wherein the winding conductor (3) is connected to a switching line (2) which is designed to connect the winding (1) to other windings, characterised in that the connection of the switching line (2) to the winding conductor (3) is arranged inside the winding (1).
2. Winding assembly according to claim 1, characterised in that the connection between the switching line (2) and the winding conductor (3) is a crimp connection.
3. Winding assembly according to claim 1 or 2, characterised in that a connecting element (4) which establishes the connection between the switching line (2) and the winding conductor (3) is surrounded by an electrical shielding (6) .
4. Winding assembly according to claim 3, characterised in that the electrical shielding (6) also surrounds the part of the winding conductor (3) adjoining the connecting element (4) and the part of the switching line (2) adjoining the connecting element (4).
5. Winding assembly according to claim 3 or 4, characterised in that the electrical shielding (6) comprises a conductive layer which at least surrounds the connecting element (4).
6. Winding assembly according to claim 3, 4 or 5, characterised in that the electrical shielding (6), the part of the winding conductor (3) adjoining the connecting element (4) and the part of the switching line (2) adjoining the connecting element (4) are surrounded by a common insulation (7).
7. Winding assembly according to one of the preceding claims, characterised in that part of the winding (1) is still located both radially outside a connection of a switching line (2) to a winding conductor (3) and also axially before and after this connection of the switching line (2) to the winding conductor (3).
8. Winding assembly according to one of the preceding claims, characterised in that part of the winding (1) is still located both radially inside a connection of a switching line (2) to a winding conductor (3) and also axially before and after this connection of the switching line (2) to the winding conductor (3).
9. Winding assembly according to one of the preceding claims, characterised in that part of the winding (1) is still located radially inside, radially outside, axially before and axially after a connection of a switching line (2) to a winding conductor (3).
10. Transformer, in particular a power transformer, preferably an oil-filled distribution transformer, having a winding assembly according to one of claims 1 to 9.

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