GB1582369A - Winding for transformers and chokes having several parallel branches which are interconnected - Google Patents

Abstract

In windings consisting of a plurality of winding conductors which are electrically connected in parallel, said winding conductors normally change their position in the winding from one winding section to the next. In the case of the present winding, each of the parallel branches (1, 2, 3) is one of a plurality of concentric cylindrical windings, which are divided by radial cross-jointed channels (4) into axial sections (5, 6, 7), and exclusively axial cooling channels (8) are provided at least within the individual sections (5, 6, 7), each of the sections (5, 6, 7) consisting of flat coils, which are wound directly on one another in the axial direction, in a double-coil circuit (a to b; b to c) having at least two turns (a to b; b to c) per flat coil, and the parallel branches (1, 2, 3) being in each case spaced apart radially one above the other within the same section (5, 6, 7). These cylindrical windings are wound in a plurality of successive operations, in each case starting at the same winding end. These windings are suitable for use as the high-voltage winding in transformers having rated voltages above 400 kV and for transformers having VA ratings less than 400 kVA and rated voltages less than 400 kV. <IMAGE>

Description

(54) A WINDING FOR TRANSFORMERS AND CHOKES HAVING SEVERAL P ARALLEL BRANCHES WHICH ARE INTERCONNECTED (71) We, TRANSFORMATOREN UNION AKTIENGESELLSCHAFT, of Deckerstlasse 5, 7 Stuttgart-Bad Cannstatt, Federal Republic of Germany, a German Body Corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a winding for transformers and chokes having several parallel branches which are interconnected and have cooling channels.

Windings constructed in this way are used in plant for high power and high voltages in order to keep the power loss arising as low as possible on the one hand and on the other hand in order to ensure sufficient cooling of the winding. In recent times so-called continuously wound coil windings which have been used to a considerable extent are known particularly for this purpose having combined radial and axial cooling through radial coil channels and longitudinal channels. This winding arrangement is used to a large extent up to and including a high tension voltage of 110 kV and moreover in the normal region of high voltage windings up to 400 kV.

In relation to single layer windings with purely longitudinal cooling which are also known, these continuously wound coil windings with combined radial and axial cooling have the disadvantage of a fairly small space factor, i.e. a higher space requirement and higher manufacturing costs. The single layer winding which is more advantageous from. this point of view can only be used, however, at the most for plant up to and including voltages of the order of 220 kV, taking its surge voltage resistance into account, and moreover is limited in its application range by the smallest possible axial conductor dimensions of flat edged partial conductors of twin or twisted conductors.

For this reason, at a voltage of 220 kV for example the smallest three-phase output possible with a single layer winding is approximately 400 MVA.

The invention seeks to create a winding which may be used with a large space factor and may be used for 400 kV windings as well as in a power range extended towards fairly small rated power at fairly low series voltages.

According to the invention, there is provided a winding for transformers and chokes comprising a plurality of parallel branches, each parallel branch comprising a conductor wound to provide a plurality of concentric tubular winding sections disposed in axially separation portions by radial interconnection channels and also separated by longitudinal cylindrical cooling channels so as to be at different radial distances within the individual axial portions, each of the winding sections comprising disc coils in double coil connection with at least two turns per coil and wound directly axially adjacent each other, the winding sections being interconnected within the radial channels so that each of the parallel branches includes a winding section at each radial distances.

By the term "disc coil in double coil connection" is meant an arrangement in which, in each pair of axially adjacent disc coils, the path of the conductor winds from the outermost turn of the first disc coil inwardly to the innermost turn of that coil, then transposes to the innermost turn of the adiacent coil and then progresses outwardly winding in the same sense to the outermost turn of that coil whereafter it transposes to the first turn of the first coil of the next pair.

Thus the parallel branches may be wound in stages one after the other beginning at one end of the winding, in that in the first operation the first portion of the innermost tubular winding is wound, in the second operation the first portion of the second tubular windings is wound as well as the second portion of the inntermost tubular winding continuously with the same conductor, in the third operation the first portion of the third tubular winding is wound as well as the second portion of the second tubular winding continuously with the same conductor, and the third portion of the first tubular windings is wound still with the same conductor and finally after corresponding further operations, in the last operation the last portion of the outermost tubular winding is wound so that there is always only one conductor running off from a supply drum.

The winding in accordance with the invention with purely longitudinal cooling and parallel branches which are interconnected is comparable with a known simple single layer winding with respect to space requirements and method of manufacture. However the winding of the invention has a many times greater series capacitance and at least twice as large an axial dimensioning of the conductor for the same number of turns and the same length of the winding as the known layer winding.The winding in accordance with the invention is therefore able to be used advantageously where previously coil windings wound continuously inside each other or combined coil windings were used, taking into consideration the surge voltage resistance, for example, in windings of 400 kV or taking the axial conductor dimension into consideration, for example in high tension voltage windings of 220 kV for transformers having a power below 400 MVA.

According to advantageous further refinement of the invention turbulance promoting strips made of insulating material and projecting outwardly into the axial cooling channel may be wound into the individual portions of the tubular windings for the purpose of producing a turbulant flow, there may be arranged in the disc coils of at least one tubular winding channels, maintained by grid like structures, lying behind each other in an axial direction, to form additional axial cooling channels.

According to preferred embodiments of the invention the conductor may be constructed as a twin, triple, quadruple or twisted conductor and, in order to increase the surge voltage resistance and the series capacitance at the connecting pieces between the two disc coils, insulating material having a greater voltage resistance than paper may be used as the covering instead of paper. Such a material is that sold under the Registered Trade Mark "Aramid".

The invention will now be described in greater detail by way of example with refer, ence to the drawings in which: Figure 1 shows a winding with three parallel branches with the coils in cross connection; Figure 2 shows the state of manufacture after a total of two operating processes has been completed; and Figure 3 represents an arrangement of the conductor in two disc coils of a double coil circuit.

Starting from an output line 9, the conductor is divided into the inputs a of parallel branches 1, 2 and 3 of a winding shown in Figure 1 having axial portions 5, 6 and 7 of' a tubular winding. Between the axial portions 5 and 6 or 6 and 7 are arranged radial cross-connections channels 4. Within each of the portions 5, 6 and 7, the parallel branches 1, 2 and 3 are respectively wound into three tubular winding sections which are arranged one above each other radially and are spaced to form longitudinally running cooling channels 8. Within the channels 4, the conductors are transposed so that the three winding sections associated with each branch 1, 2 or 3 are disposed in the inner middle and outer radial positions in the portions 5, 6 and 7.

In each portion 5, 6 and 7, three tubular windings sections lying one above the other radially are provided in accordance with the number of the parallel branches 1, 2 and 3, each of which tubular sections comprises a plurality of two-turn disc, coils which are disposed directly adjacent each other axially. An embodiment for two adjacent disc coils joined together in a double coil connection is shown in Figure 3.

The various transitions of the conductor are so arranged in the disc coils that the insulation of the turns needs only to be dimensioned for the voltage difference of axially adjacent conductors.

A winding which is still incomplete is shown in Figure 2 in the state of manufacture achieved in accordance with two operating processes. After manufacturing the innermost tubular winding section of the axial portion 5 in a first operating process, the winding end for a later soldering connection is prepared and placed radially to the outside. The tubular winding section of the parallel branch 2 lying concentrically thereabove is wound on to channel elements and is continued one stage deeper radially as the innermost tubular winding of the axial portion 6. Accordingly, in a manner not shown, in the third operating process, not shown, in the third operating process a tubular winding section made of adjacently disposed disc coils is wound in double coil connection for the parallel branch 3 in the axial portion 5 and in the same operating process, without separating the conductor, it is continued in the axial portions 6 and 7 offset radially inwards by one step in each case.

WHAT Nvf, CLATM IS:- 1. A winding for transformers and chokes comDrising a pluralitv - of parallel branches, each parallel branch comprising a conductor wound to provide a plurality

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. tubular windings is wound still with the same conductor and finally after corresponding further operations, in the last operation the last portion of the outermost tubular winding is wound so that there is always only one conductor running off from a supply drum. The winding in accordance with the invention with purely longitudinal cooling and parallel branches which are interconnected is comparable with a known simple single layer winding with respect to space requirements and method of manufacture. However the winding of the invention has a many times greater series capacitance and at least twice as large an axial dimensioning of the conductor for the same number of turns and the same length of the winding as the known layer winding.The winding in accordance with the invention is therefore able to be used advantageously where previously coil windings wound continuously inside each other or combined coil windings were used, taking into consideration the surge voltage resistance, for example, in windings of 400 kV or taking the axial conductor dimension into consideration, for example in high tension voltage windings of 220 kV for transformers having a power below 400 MVA. According to advantageous further refinement of the invention turbulance promoting strips made of insulating material and projecting outwardly into the axial cooling channel may be wound into the individual portions of the tubular windings for the purpose of producing a turbulant flow, there may be arranged in the disc coils of at least one tubular winding channels, maintained by grid like structures, lying behind each other in an axial direction, to form additional axial cooling channels. According to preferred embodiments of the invention the conductor may be constructed as a twin, triple, quadruple or twisted conductor and, in order to increase the surge voltage resistance and the series capacitance at the connecting pieces between the two disc coils, insulating material having a greater voltage resistance than paper may be used as the covering instead of paper. Such a material is that sold under the Registered Trade Mark "Aramid". The invention will now be described in greater detail by way of example with refer, ence to the drawings in which: Figure 1 shows a winding with three parallel branches with the coils in cross connection; Figure 2 shows the state of manufacture after a total of two operating processes has been completed; and Figure 3 represents an arrangement of the conductor in two disc coils of a double coil circuit. Starting from an output line 9, the conductor is divided into the inputs a of parallel branches 1, 2 and 3 of a winding shown in Figure 1 having axial portions 5, 6 and 7 of' a tubular winding. Between the axial portions 5 and 6 or 6 and 7 are arranged radial cross-connections channels 4. Within each of the portions 5, 6 and 7, the parallel branches 1, 2 and 3 are respectively wound into three tubular winding sections which are arranged one above each other radially and are spaced to form longitudinally running cooling channels 8. Within the channels 4, the conductors are transposed so that the three winding sections associated with each branch 1, 2 or 3 are disposed in the inner middle and outer radial positions in the portions 5, 6 and 7. In each portion 5, 6 and 7, three tubular windings sections lying one above the other radially are provided in accordance with the number of the parallel branches 1, 2 and 3, each of which tubular sections comprises a plurality of two-turn disc, coils which are disposed directly adjacent each other axially. An embodiment for two adjacent disc coils joined together in a double coil connection is shown in Figure 3. The various transitions of the conductor are so arranged in the disc coils that the insulation of the turns needs only to be dimensioned for the voltage difference of axially adjacent conductors. A winding which is still incomplete is shown in Figure 2 in the state of manufacture achieved in accordance with two operating processes. After manufacturing the innermost tubular winding section of the axial portion 5 in a first operating process, the winding end for a later soldering connection is prepared and placed radially to the outside. The tubular winding section of the parallel branch 2 lying concentrically thereabove is wound on to channel elements and is continued one stage deeper radially as the innermost tubular winding of the axial portion 6.Accordingly, in a manner not shown, in the third operating process, not shown, in the third operating process a tubular winding section made of adjacently disposed disc coils is wound in double coil connection for the parallel branch 3 in the axial portion 5 and in the same operating process, without separating the conductor, it is continued in the axial portions 6 and 7 offset radially inwards by one step in each case. WHAT Nvf, CLATM IS:-

1. A winding for transformers and chokes comDrising a pluralitv - of parallel branches, each parallel branch comprising a conductor wound to provide a plurality

of concentric tubular winding sections disposed in axially separated portions by radial interconnection channels and also separated by longitudinal cylindrical cooling channels so as to be at different radial distanes within the individual axial portions, each of the winding sections comprising dise coils in double coil connection with at least two turns per coil and wound directly axially adjacent each other, the winding sections being interconnected within the radial channels so that each of the parallel branches includes a winding section at each radial distance.

2. A winding according to Claim 1, wherein the parallel branches are wound in stages one after the other beginning at one winding end, in that in the first winding stage the first portion of the innermost tubular winding is wound, in the second winding stage the first portion of the second tubular winding and the second portion of the innermost tubular winding is wound continuously with the same conductor, and in the third tubular winding, the second portion of the second tubular winding and the third portion of the first tubular winding is wound continuously with the same conductor and finally after corresponding further winding stages, in the last winding stage the last portion of the outermost tubular winding is wound so that there is always only one conductor running off a supply drum.

3. A winding according to Claim 1 or 2, wherein turbulence promoting strips made of insulating material and projecting outwardly into the axial cooling channels are wound into the individual portions of the tubular winding, in order to produce a turbulent flow.

4. A winding according to any one of Claims 1 to 3, wherein channels lying one behind the other in an axial direction are arranged in the disc coils of at least one tubular winding and are maintained by grid like structures in order to form additional axial cooling channels.

5. A winding according to any one of Claims 1 to 4, wherein the conductor is constructed as a twin. triple or quadruple conductor.

6. A winding according to any one of Claims 1 to 4, wherein the conductor is constructed as a twisted conductor.

7. A winding according to any one of Claims 1 to 6, wherein in that, in order to increase the surge voltage resistance and the longitudinal capacitance at the connecting pieces between the disc coils the conductors are covered by insulating materials having a greater voltage resistance than paper.

8. A winding for transformers and chokes substantially as described herein with reference to the drawings.