US3766504A

US3766504A - Interleaved transformer winding having three parallel connected conductors

Info

Publication number: US3766504A
Application number: US00305387A
Authority: US
Inventors: D Yannucci; Nice R Van
Original assignee: Westinghouse Electric Corp
Current assignee: ABB Inc USA
Priority date: 1972-11-10
Filing date: 1972-11-10
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16
Also published as: FR2206567B1; BE807169A; FR2206567A1

Abstract

A disc-type interleaved winding for transformers. Current is conducted through the winding by three conductors connected in parallel and interconnected between the coil discs to provide three different conduction paths. The first and third conduction paths are transposed between adjacent coil discs and progress in radially opposite directions through adjacent coil discs. The second conduction path forms a looping pattern throughout the winding with the conductor forming the second conduction path physically positioned between the other two conductors in each coil disc.

Description

United States Patent 1191 Yannucci et al.

INTERLEAVED TRANSFORMER WINDING HAVING THREE PARALLEL CONNECTED CONDUCTORS [75] Inventors: Dean A. Yannucci, Warren,

Ohio; Robert I. Van Nice,

Sharon, Pa.

Pittsburgh, Pa.

'Assigneez Westinghouse Electric Corporation,

Filed: Nov. 10, 1972 [21] Appl. No.: 305,387

US. Cl. 336/70, 336/187 Int. Cl. 1101f 27/28 Field of Search 336/186, 187, 69,

[56] References Cited UNITED STATES PATENTS 10/1967 Baker et al. 336/187 7 9/1969 Dutton 336/187 1 Oct. 16, 1973 FOREIGN PATENTS OR APPLICATIONS 786,126 11/1957 Great Britain.... 336/187 271968 Nether1ands.... 336/187 Primary Examiner--Thomas J. Kozma Attorney-A. T. Stratton et al.

[57] ABSTRACT A disc-type interleaved winding for transformers. Current is conducted through the winding by three conductors connected in parallel and interconnected between the coil discs to provide three different conduction paths. The first and third conduction paths are transposed between adjacent coil discs and progress in radially opposite directions through adjacent coil discs. The second conduction path forms a looping pattern throughout the winding with the conductor forming the second conduction path physically positioned between the other two conductors in each coil disc.

9 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, in general, to electrical inductive apparatus and, more specifically, to interleaved transformer windings having three conductors.

2. Description of the Prior Art When a transformer winding is constructed to carry a relatively large amount of current, multiple conductors connected in parallel are frequently used. By using multiple conductors instead of one large conductor, the eddy current losses in the winding are reduced, and connections and transpositions within the winding are less difficult to make due to the better flexibility of the multiple conductor lead.

The use of interleaved windings to increase the series capacitance of a winding structure is well known. Due to the increased series capacitance provided by interleaving, the impulse voltage characteristics of the winding structure are improved. It is also known that the series capacitance of transformer windings is related to the voltage difference between adjacent conductors, with a larger voltage difference providing more energy storage and a higher series capacitance. v

Arrangements for interleaving conductors to increase the series capacitance of a transformer winding having three conductors connected in parallel are known by those skilled in the art. Although the prior art arrangements are beneficial electrically, the construction thereof is complicated and costly due to the physical arrangement of the interleaving connections and to the insulation required around the conductors.

It is desirable, and it is an object of this invention, to provide a three-conductor interleaved transformer winding which may be constructed easily and inexpensively.

SUMMARY OF THE INVENTION There is disclosed herein a new and useful threeconductor interleaved transformer winding. The winding includes at least four coil discs which are axially located at different positions in the winding. The three conductors are wound and interconnected to provide first, second and third conduction paths through the discs of the winding. The first and third conduction paths progress in a first radial direction through one coil disc and then in a second radial direction, which is opposite to the first radial direction, through an adja cent coil disc. The same pattern is repeated in the other discs of the winding. Thus, the first and third conduction paths progress in opposite directions in adjacent coil discs throughout the winding.

The coil discs are arranged into first, second, third and fourth axial positions throughout the winding. The second conduction path forms a looping path throughout the winding. The second conduction path progresses in the second radial direction through the coil disc in the second position, then in the first radial direction through the coil disc in the first position, then in the second radial direction through the coil disc in the fourth position, and then in the first radial direction through the coil disc in the third position. This pattern is repeated throughout every four discs of the winding.

With the arrangement disclosed herein, conductor insulation having a relatively high voltage breakdown strength is only required on one of the three conductors. The interleaving of the conductors provides a winding having a high series capacitance. In addition, the interconnections between coil discs are relatively easy to construct.

BRIEF DESCRIPTION OF THE DRAWING Further advantages and uses of this invention will become more apparent when considered in view of the following detailed description and drawing, in which:

FIG. 1 is a partial, sectional view of a transformer having a three-conductor interleaved winding; and

FIG. 2 is a schematic diagram of the interleaved winding shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Throughout the following description, similar reference characters refer to similar members or elements in all the figures of the drawing.

Referring now to the drawings, and FIG. 1 in particular, there is shown a partial, sectional view of a power transformer having an interleaved winding 10. The winding 10 is illustrated as a high-voltage winding which is positioned around the low-voltage winding 12. Insulation 14 insulates the low-voltage winding 12 from the magnetic core 16 and from the interleaved highvoltage winding 10.

The winding 10 includes a plurality of pancake winding sections or coil discs, such as

coil discs

18, 20, 22 and 24. The coil discs 18 20, 22 and 24 are positioned at different axial positions throughout the winding 10 as is illustrated in FIG. 1. It is within the contemplation of this invention that more than four coil discs may comprise the winding 10. The

terminals

26, 28 and 30 may be connected together and to associated electrical apparatus, such as a high-voltage bushing. Similarly, the terminals 32, 34 and 36 may be connected together and to a bushing or they may be connected to additional coil discs without being connected together when the winding 10 comprises more than four coil discs.

Each coil disc is wound with three conductors which are denoted as conductors A, B and C. The conductors are spirally wound and are radially disposed on each other throughout the winding 10. In coil disc 18, the conductor A at conductor position A0 is wound around the low-voltage winding 12, the conductor B is wound around the conductor A, and the conductor C is wound around the conductor B. Although not completely illustrated, insulation material covers each conductor. Also, each conductor may comprise more than one wire strand.

Although the conductor positions A0, A1, A2, etc. designate different physical positions of the electrical conductor A, convenience and commonly accepted practice will be adhered to in this description by referring to such positions as conductors. Each group of three conductors completes a conductor-turn. For example, conductors A0, B3 and C0 form the start or first conductor-turn 38 of coil disc 18, and conductors A9, B12 and C9 form the finish or second conductor turn 40 of the coil disc 22. Any number of conductor-turns may be wound between the first and second conductorturns; however, only two intermediate conductor-turns are illustrated in each coil disc of FIG. 1 for clarity. The winding may be constructed in reverse relationship without departing from the spirit of the invention. In reverse relationship, the first conductor-tums, such as the first conductor-turn 38, would be positioned on the outside of the winding as finsih conductor-turns, such as the second conductor-turn 40.

The numbers following the conductor designators A,

B and C indicate the relative voltage existing on the particular conductor at that location. For example, the voltage existing on conductor A4 in coil disc 20 is two times the voltage existing on conductor A2 in coil disc 18 since the conductor A has progressed two turns in going from conductor A2 to conductor A4. The conductors around which the other conductors in the same conductor-turn are wound, such as conductors A0 and C6, will be referred to as the first conductor in the conductor-turns. The conductors which are wound around the other conductors in the same conductor-turn, such as conductors C0 and A6, will be referred to as the third conductor in the conductor-turns. The conductors which are located between the other two conductors of the same conductor-turn, such as conductors B3 and B9, will be referred to as the second conductor in the conductor-turns. Although referred to as conductors, it'is emphasized again that they denote a position in a conductor-turn and may or may not be the same physical conductor at a similar position in another conductor-turn.

As can be seen in FIG. 1, the first conductor-turn 38 of the first coil disc 18 has its first and third conductors, A and C respectively, connected to the

terminals

26 and 28. The terminal 30 is connected to the second conductor B of the second conductor-turn of the second coil disc 20. Conductors A and C are spirally wound around the low-voltage winding 12 and progress outwardly to the second conductor-turn of the coil disc 18. Conductor B spirals inwardly to the first conductorturn of the coil disc 20 and is interconnected to the second conductor B of the first conductor-turn 38 of the first coil disc 18 by the interconnecting lead 44.

The conduction paths between the terminals 26 and 32 and between the

terminals

28 and 34 progress from the first conductor-turn to the second conductor-turn of coil disc 18, from the second conductor-turn to the first conductor-turn of coil disc 20, from the first conductor-turn to the second conductor-turn of the coil disc 22, and from the second conductor-turn to the first conductor-turn of coil disc 24. The transposed interconnecting leads 46, 48 and 50 connect the appropriate conductors together between adjacent conductorturns. Transposing the

leads

46, 48 and 50 reduces losses caused by circulating currents in the conductors A and C.

The conduction path between the terminals 30 and 36 progresses from the second conductor-turn to the first conductor-turn of the coil disc 20, from the first conductor-turn to the second conductor-turn of the coil disc 18, from the second conductor-turn to the first conductor-turn of the coil disc 24, and from the first conductor-turn to the second conductor-turn of the coil disc 22. lnterconnecting leads 44, 52 and 54 provide the necessary electrical connection between the appropriate conductor-turns.

With the arrangement shown in FIG. 1, the voltage between the conductors A and C is substantially equal to zero in the same conductor-turn. Thus, where the conductors A and C are physically adjacent to each other, such as in the transposed leads 46, 48 and 50, the insulation material disposed on the conductors A and C need not have a relatively high voltage breakdown strength. Since the voltage between the conductors of radially adjacent conductor-turns is equal to the voltage of one turn, the insulation on these conductors, such as CO and Al, must only be sufficient to insulate the voltage equal to the voltage induced in one turn of the conductor.

Prior art three-conductor arrangements require a substantial amount of conductor insulation because they have a considerable amount of voltage between each conductor of a conductor-turn. In the present invention, the greatest amount of voltage difference exists between conductor B and the other conductors. Thus, relatively high strength insulation need only be applied to the conductor B. Therefore, a space and material savings may be realized by utilizing the present invention over the prior art. The additional insulation around the conductor B is indicated by the thicker insulation 58 which extends around conductor B. It is within the contemplation of this invention that the insulation 58 need not be thicker if it consists of a material having a higher breakdown strength than the insulation around conductors A and C.

The degree of interleaving of the conductors used in this invention is known as twin interleaving, that is, where the maximum voltage difference between conductors equals the voltage developed in all the turns of one coil disc. One looping conductor path is required. The other two conductor paths are continuous throughout the winding 10. Within the winding 10, no interconnections are required which connect a first conductor-turn to a second conductor-turn. Thus, relatively long interconnections are not required;

FIG. 2 is an electrical schematic diagram representing the winding 10. Corresponding to FIG. 1, the direction indicated by the arrow 60 represents the direction going from the inside of the winding 10 to the outside of the winding 10. Since as previously stated, the winding 10 may be constructed in reverse relationship, the direction indicated by the arrow 60 will be referred to as the first direction to eliminate reference to the physical construction of the winding 10. Similarly, arrow 62 represents a second direction which is opposite to that of the first direction.

From FIG. 2, it can be seen that a first conduction path begins at terminal 26 and progresses in the first direction through coil disc 18, in the second direction through coil disc 20, in the first directionthrough coil disc 22, and in the second direction through coil disc 24. A third conduction path between the

terminals

28 and 34 progresses in a similar manner. A second conduction path between the terminals 30 and 36 pro-' gresses in the second direction through coil disc 20, in the first direction through coil disc 18, in the second direction through coil disc 24, and in the first direction through coil disc 22. The vertical position of the conductor coils, such as

coils

64, 66 and 68 represents the relative radial position of the conductor in the physical accompanying drawing, shall be interpreted as illustrative rather than limiting.

We claim as our invention:

1. A winding for electrical inductive apparatus, comprising:

at least, first, second, third and fourth coil discs, said second coil disc being axially positioned between said first and third coil discs, said third coil disc being axially positioned between said second and fourth coil discs;

first, second and third electrical conductors forming first, second and third conduction paths through said coil discs;

said first and third conduction paths progressing in a first direction through said first coil disc, in a second direction through said second coil disc, in the first direction through said third coil disc, and in the second direction through said fourth coil disc, said first and second directions being opposite each other; and

said second conduction path beginning in second coil disc and progressing in the second direction through said second coil disc, in the first direction through said first coil disc, in the second direction through said fourth coil disc, and in the first direction through said third coil disc, respectively.

2. The winding of claim 1, wherein the second conductor is positioned between the first and third conductors throughout each of said coil discs.

3. The winding of claim 1, wherein the first and third conductors are transposed between each coil disc.

4. The winding of claim 1, wherein the second conductor is covered with an insulation structure having a higher voltage breakdown strength than that of insulation covering the first and third conductors.

5. A winding for electrical inductive apparatus, comprising:

at least, first, second, third and fourth coil discs having first and second conductor-turns, said second coil disc being axially positioned between said first and third coil discs, said third coil disc being axially positioned between said second and fourth coil discs;

said first and third conduction paths beginning at the first conductor-turn of said first coil disc and progressing to the second conductor-turn of said first coil disc, to the second conductor-turn of said second coil disc, to the first conductor-turn of said second coil disc, to the first conductor-turn of said third coil disc, to the second conductor-turn of said third coil disc, to the second conductor-turn of said fourth coil disc, and to the first conductor-turn of said fourth coil disc; and

said second conduction path beginning at the second conductor-turn of said second coil disc and progressing to the first conductor-turn of said second coil disc, to the first conductor-turn of said first coil disc, to the second conductor-turn of said first coil disc, to the second conductor-turn of said fourth coil disc, to the first conductor-turn of said fourth coil disc, to the first conductor-turn of said third coil disc, and to the second conductor-turn of said third coil disc.

6. The winding of claim 5, wherein the second conductor is radially positioned between the first and third conductors in every conductor-turn.

7. The winding of claim 5, wherein the first and third conductors are transposed between each coil disc.

8. The winding of claim 5, wherein the second conductor is covered with an insulation structure having a higher voltage breakdown strength than that of insulation covering the first and third conductors.

9. A winding for electrical inductive apparatus, comprising;

at least, first, second, third and fourth coil discs, said second disc being axially positioned between said first and third coil discs, said third coil disc being axially positioned between said second and fourth coil discs;

first, second and third conductors each comprising at least one electrical strand, said second conductor being radially disposed over said first conductor and said third conductor being radially disposed over said second conductor, said first, second and third conductors being collectively and spirally disposed through each of said coil discs to form at least first and second conductor-turns, the first conductor-turn of each coil disc being located at substantially the same radial position in said winding, said conductors being electrically connected between conductor-turns to provide first, second and third conduction paths;

said first conduction path beginning at the first conductor of the first conductor-turn of said first coil disc and progressing to the first conductor of the second conductor-turn of said first coil disc, to the third conductor of the second conductor-turn of said second coil disc, to the third conductor of the first conductor-turn of said second coil disc, to the first conductor of the first conductor-turn of said third coil disc, to the first conductor of the second conductor-turn of said third coil disc, to the third conductor of the second conductor-turn of said fourth coil disc, and to the third conductor of the first conductor-turn of said fourth coil disc;

said second conduction path beginning at the second conductor of the second conductor-turn of said second coil disc and progressing to the second conductor of the first conductor-turn of said second coil disc, to the second conductor of the first conductor-turn of said first coil disc, to the second conductor of the second conductor-turn of said first coil disc, to the second conductor of the second conductor-turn of said fourth coil disc, to the second conductor of the first conductor-turn of said fourth coil disc, to the second conductor of the first conductor-turn of said third coil disc, and to the second conductor of the second conductorturn of said third coil disc; and

said third conduction path beginning at the third conductor of the first conductor-turn of said first coil disc and progressing to the third conductor of the second conductor-turn of said first coil disc, to the first conductor of the second conductor-turn of said second coil disc, to the first conductor of the first conductor-turn of said second coil disc, to the third conductor of the first conductor-turn of said third coil disc, to the third conductor of the second conductor-turn of said third coil disc, to the first conductor of the second conductor-turn of said fourth coil disc, and to the first conductor of the first conductor-turn of said fourth coil disc.

Claims

1. A winding for electrical inductive apparatus, comprising: at least, first, second, third and fourth coil discs, said second coil disc being axially positioned between said first and third coil discs, said third coil disc being axially positioned between said second and fourth coil discs; first, second and third electrical conductors forming first, second and third conduction paths through said coil discs; said first and third conduction paths progressing in a first direction through said first coil disc, in a second direction through said second coil disc, in the first direction through said third coil disc, and in the second direction through said fourth coil disc, said first and second directions being opposite each other; and said second conduction path beginning in second coil disc and progressing in the second direction through said second coil disc, in the first direction through said first coil disc, in the second direction through said fourth coil disc, and in the first direction through said third coil disc, respectively.

5. A winding for electrical inductive apparatus, comprising: at least, first, second, third and fourth coil discs having first and second conductor-turns, said second coil disc being axially positioned between said first and third coil discs, said third coil disc being axially positioned between said second and fourth coil discs; first, second and third electrical conductors forming first, second and third conduction paths through said coil discs; said first and third conduction paths beginning at the first conductor-turn of said first coil disc and progressing to the second conductor-turn of said first coil disc, to the second conductor-turn of said second coil disc, to the first conductor-turn of said second coil disc, to the first conductor-turn of said third coil disc, to the second conductor-turn of said third coil disc, to the second conductor-turn of said fourth coil disc, and to the first conductor-turn of said fourth coil disc; and said second conduction path beginning at the second conductor-turn of said second coil disc and progressing to the first conductor-turn of said second coil disc, to the first conductor-turn of said first coil disc, to the second conductor-turn of said first coil disc, to the second conductor-turn of said fourth coil disc, to the first conductor-turn of said fourth coil disc, to the first conductor-turn of said third coil disc, and to the second conductor-turn of said third coil disc.

9. A winding for electrical inductive apparatus, comprising; at least, first, second, third and fourth coil discs, said second disc being axially positioned between said first and third coil discs, said third coil disc being axially positioned between said second and fourth coil discs; first, second and third conductors each comprising at least one electrical strand, said second conductor being radially disposed over said first conductor and said third conductor being radially disposed over said second conductor, said first, second and third conductors being collectively and spirally disposed through each of said coil discs to form at least first and second conductor-turns, the first conductor-turn of each coil disc being located at substantially the same radial position in said winding, said conductors being electrically connected between conductor-turns to provide first, second and third conduction paths; said first conduction path beginning at the first conductor of the first conductor-turn of said first coil disc and progressing to the first conductor of the second conductor-turn of said first coil disc, to the third conductor of the second conductor-turn of said second coil disc, to the third conductor of the first conductor-turn of said second coil disc, to the first conductor of the first conductor-turn of said third coil disc, to the first conductor of the second conductor-turn of said third coil disc, to the third conductor of the second conductor-turn of said fourth coil disc, and to the third conductor of the first conductor-turn of said fourth coil disc; said second conduction path beginning at the second conductor of the second conductor-turn of said second coil disc and progressing to the second conductor of the first conductor-turn of said second coil disc, to the second conductor of the first conductor-turn of said first coil disc, to the second conductor of the second conductor-turn of said first coil disc, to the second conductor of the second conductor-turn of said fourth coil disc, to the second conductor of the first conductor-turn of said fourth coil disc, to the second conductor of the first conductor-turn of said third coil disc, and to the second conductor of the second conductor-turn of said third coil disc; and said third conduction path beginning at the third conductor of the first conductor-turn of said first coil disc and progressing to the third conductor of the second conductor-turn of said first coil disc, to the first conductor of the second conductor-turn of said second coil disc, to the first conductor of the first conductor-turn of said second coil disc, to the third conductor of the first conductor-turn of said third coil disc, to the third conductor of the second conductor-turn of said third coil disc, to the first conductor of the second conductor-turn of said fourth coil disc, and to the first conductor of the first conductor-turn of said fourth coil disc.