US3538473A - Stranded winding for high current electric apparatus - Google Patents

Stranded winding for high current electric apparatus Download PDF

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Publication number
US3538473A
US3538473A US730169A US3538473DA US3538473A US 3538473 A US3538473 A US 3538473A US 730169 A US730169 A US 730169A US 3538473D A US3538473D A US 3538473DA US 3538473 A US3538473 A US 3538473A
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winding
transposition
strands
conductor
radially
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US730169A
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George E Leibinger
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CBS Corp
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General Electric Co
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Assigned to WESTINGHOUSE ELECTRIC CORPORATION, A CORP OF PA. reassignment WESTINGHOUSE ELECTRIC CORPORATION, A CORP OF PA. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GENERAL ELECTRIC COMPANY
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/2871—Pancake coils

Definitions

  • My invention relates to windings for electric induction apparatus, and particularly to windings formed of stranded conductor wherein a single helically wound conductor of high current carrying capacity is formed of a plurality of separately insulated conductor strands stacked together in radially superposed relation and electrically connected in parallel circuit relation.
  • winding conductor In high current electric windings for power transformers, reactors and the like, it is a common practice to form the winding conductor of a plurality of strands, usually stacked in radial superposition to maximize the number of turns in a single cylindrical winding layer.
  • the strands of such conductor are usually separately insulated even though all strands are connected together at their ends. Such insulation has the primary purpose of subdividing the conductor to minimize local eddy currents resulting from flux traversing the conductor itself.
  • coils formed by radially outer strands include more flux than do coils formed by radially inner strands (i.e., with respect to the midpoint between the inner and outer peripheries of the helical conductor).
  • the flux difference results in appreciable difference in the number of volts per turn in the radially spaced-apart strands of a single conductor, i.e., the reactive voltage drop per turn in a reactor or the induced volts per turn in a transformer winding is not the same for each of a plurality of radially stacked strands. Since the conductor strands are connected in parallel circuit relation at their ends, each pair of strands forms a conductive loop in which circulating current will be set up as a result of such voltage differences.
  • FIG. 1 is a fragmentary cross-sectional view of an electric transformer having primary and secondary windings concentrically wound upon a single core leg to illustrate the origin of leakage flux between such windings;
  • FIG. 2 is a similar fragmentary cross-sectional view of a two-winding transformer showing in more detail the configuration of the leakage flux field;
  • FIG. 3 is a fragmentary cross-sectional view similar to those of FIGS. 1 and 2, but illustrating also a typical stranded winding conductor;
  • FIGS. 4 and 5 are detailed multiple cross-sectional views illustrating several transposition sequences for a multistrand winding such as shown at FIG. 3;
  • FIG. 7 is a fragmentary cross-sectional view of a multistrand winding transposed in accordance with my mventron.
  • I have illustrated my lnvention by way of example in connection with a transformer of the concentric winding type as commonly used for large power transformers, such as furnace transformers and others having low voltage windings of high current-carrying capacity.
  • I have shown in fragmentary cross-sectional view a transformer comprising a magnetizable core including a core leg 10 and a yoke portion 11.
  • the transformer leg 10 of FIG. 1 may, of course, be one winding leg of a three-phase or other polyphase transformer.
  • a helical high voltage primary winding 12 and a concentric helical secondary winding 13 of high current carrying capacity Upon the core leg 10 is wound a helical high voltage primary winding 12 and a concentric helical secondary winding 13 of high current carrying capacity. It will be understod by those skilled in the art that when both windings are carrying current under load conditions the voltages of the windings 12 and 13 are vectorially in substantially opposite phase relation and the currents in the windings are also in substantially opposing phase relation.
  • the current in the primary winding 12 includes as a component thereof the exciting current. On ampere turn basis this exciting current is the vectorial different between the primary and secondary currents and has the effect of producing in the core 10, 11 a main flux represented at FIG.
  • the primary and secondary fluxes p and 5 within the core leg 10 are in opposite directions. It is the dilference between the total primary and secondary flux which results in the main magnetizing flux 41, Similarly, the components of stray primary and secondary flux radially beyond both of the windings 12 and 13 are in opposite directions and tend to cancel each other. In the space between the primary and secondary windings, however, the stray flux from both the primary and secondary windings are in the same direction and reinforce each other to establish a flux of considerable proportion known as leakage flux and comprising the components and At FIG.
  • the leakage fiux components do not uniformly include within their loop paths all of the primary and secondary winding turns, but in fact fringe out appreciably at the axially remote ends of the windings so that the axial component of leakage flux at opposite ends of the windings are of considerably less intensity than the axial component of leakage flux at the axial midpoint of the windings.
  • the leakage flux traverses not only the space between the primary and secondary windings but also passes in part through the conductors of the windings themselves, this being shown particularly with respect to the large cross-section conductors of the secondary winding 13.
  • each winding turn is formed of two stacks of radially superposed strands (1 to -4 and 5 to 8 at FIG. 3) with the two stacks axially juxtaposed in side-by-side relation.
  • the eight separately insulated conductor strands are electrically connected together, as illustrated by the lack of insulation therebetween in the axially endmost turns. In practice, of course, electrical connection of the ends of the conductors is made in the leads beyond the end turns of the winding.
  • FIG. 4 I have shown by a plurality of successive cross-sectional views 4a to 4 inclusive, one sequence in which the eight conductor strands shown atFIG. 4 may be radially transposed with respect to each other at selected axially spaced-apart points along the length of the helical winding 13.
  • Each cross-sectional view at FIG. 4 is of a single winding turn, but it will be understood by those skilled in the art that these turns, while axially spaced apart, are not ordinarily axially adjacent as shown, but
  • the transposition illustrated at FIG. 4 is a so-called progressive type.
  • the stranded conductor comprises an even number of strands with four radially superimposed strands in each of two axially juxtaposed stacks.
  • FIG. 4a shows the initial position of the strands as the conductor enters the first turn of the winding 13.
  • FIG. 4b illustrates a first transposition point in which the stack of strands 1 to 4 has been shifted radially outward by one strand position with respect to the adjacent stack of strands 5 to 8.
  • FIG. 4a shows a second transposition point at which the radially innermost and radially outermost strands 5 and 4, respectively, have been shifted in opposite directions axially to place each of them in the adjacent stack of conductors.
  • FIG. 4d shows a succeeding transportation point at which the uppermost stack of conductors has been moved radially inward and back into radial alignment with the lower stack of strands.
  • the conductor strand 1 may be moved to its radially outermost position at FIG. 4j, While each of the other strands is moved in step-bystep progressive manner radially inward or radially outward until each strand has occupied each of the four available radially displaced strand positions. Similar progressive, or consecutive, transpositions may be continued until the conductor strand 1 has been moved continuously through all strand positions and back to its initial radially innermost and axially uppermost position.
  • each strand would be moved by eight positions at each such point rather than by one position as shown, but the transposition would still be progressive, or consecutive, in that each radial displacement would be in the same direction and by any equal number of positions within the confines of one complete transposition.
  • a high current capacity conductor formed of more than two axially juxtaposed stacks of conductor strands may be transposed progressively in like manner. See, for example, British Pat. 431,617 wherein the strands in three axially adjacent stacks are transposed in progressive sequence. If it is desired to utilize four axially adjacent stacks of strands, each pair of stacks may be progressively transposed in the manner described in connection with FIG. 4 above.
  • FIG. 5 two non-progressive types of transposition known in the art as the standard transposition and the special transportation.
  • FIGS. 5a and 5b I have illustrated a so-called standard transportation in which strand positions 1, 2, 3 and 4 are completely reversed radially at a single transposition point between censecutive winding turns.
  • Such a transposition is more fully described at column 3 of Pat. 2,710,380, DeBuda.
  • Transpositions similar to the standard and the special as described above and shown at FIG. 5 may also be carried out by transposing the conductors in groups rather than individually, as described for example in the DeBuda patent identified above. Moreover, it will be understood that the transpositions shown at FIG. 5 may be carried out with a conductor formed of two or more radial stacks of strands, each radial stack of such a conductor being transposed as at FIG. 5 independently of the other stacks.
  • transposing conductor strands in any of the sequences described above to space the transposition points uniformly along the axis of the coil.
  • utilizing special and standard transpositions it is the practice to locate the transposition points at the center and the A and points of the winding length.
  • a progressive type transposition it is the practice to separate the transposition points by equal axial distances. It should noW be noted that a progressive transposition is complete in regard to radial variation of included axial leakage flux for the several strand positions when each strand has been located once in each available radial position.
  • the voltage equalization accomplished takes account also of axial variation of included leakage flux resulting from the flux fringing effect described in connection with FIGS. 2 and 3 above.
  • uniform spacing of transposition points axially along the widing assumes that the axial component of leakage flux is of uniform intensity at all points along the winding axis. Such uniform intensity does not in fact exist because of the fringing effect.
  • the circulating currents in a helical electric winding formed of transposed multistrand conductors may be further reduced by spacing the transposition points non-uniformly along the axial length of the winding. More specifically, I find that by increasing the distance between transposition points in moving from the axial midpoint toward the axially remote ends of the Winding, greater uniformity in the volts per turn between adjacent conductor strands may be attained. For example, in a progressive type transposition with a relatively large number of transposition points, the spacing between transpositions is, according to my invention, progressively increased approaching each end of the winding, the transposition intervals being a minimum at the axial midpoint of the winding and a maximum at the axially remote ends thereor.
  • the transposition points in the opposite halves of the winding are located axially somewhat closer to the center of the winding than to the adjacent end.
  • the median position of the transposition points in each half of the winding on opposite sides of the axial midpoint is closer to the midpoint than to the adjacent end of the winding.
  • the degree of non-uniformity or asymmetry in respect to axial positioning of transposition points in each axial half of the Winding will, of course, vary in accordance with the configuration of the leakage field in the particular winding under consideration. Where the fringing of the leakage field is very slight, the inward displacement of v the median transposition point will be slight, but where the fringing effect is greater, the inward displacement of such median point will be greater.
  • median position of transposition points and median transposition point have the same meaning.
  • Such median position or point is that axial position at each side of the axial midpoint of the winding at which occurs the central one (or only one) of an odd number of transpostions on that side of the winding midpoint; or in the case of an even number of transpositions on each side of the winding midpoint it is that axial position at one side of the winding midpoint which is midway between the central pair of transpositions on that side of the winding midpoint.
  • FIG. 6 a specific graphical representation of non-uniformly displaced transposition points for a winding having a progressive type transposition.
  • the curve A represents the desired axial spacing of transposition points in a winding of the kind described at FIG. 4 in terms of the ratio of actual to average spacing at each point along the winding axis.
  • the abscissa of curve A represents turn location along wlnding axis in percentage of Winding length, the mid point of the curve horizontally being the midpoint of the Winding and represented by the axial distance point 50%.
  • the ordinant of the curve A shown at FIG. 6 represents transposition point spacing in terms of ratio to an average or uniform spacing 1.00.
  • the curve represents an optimum progression in the spacing of transpositron points along a winding having an even number of complete progressive type transpositions and characterized by a leakage flux having approximately half the intensity at the axially remote ends of the winding that it has at the winding midpoint.
  • the curve A shows that at the midpoint of the winding the spacing of transposition points is preferably about .95 of an average, or uniform spacing distance, and that such spacing distance is gradually increased from the center toward each end of the winding at a very gradual rate to positions approximately A the axial length from each end of the winding.
  • the spacing between transposition points increases sharply until the spacing reaches a maximum of approximately double the average axial spacing at each end of the winding.
  • FIG. 7 a cross-section view (at only one side of the axis) of a multistrand winding transposed non-progressively in accordance with the invention.
  • the axiallly remote ends of the windings are designated OO and the midpoint as 50%.
  • the quadrature points are designated 25% and 75%.
  • a standard transposition of a four strand single stack conductor is shown at the midpoint and designated T Near the quadrature points, but slightly displaced toward the midpoint, each axial half of the winding has a special transposition designated T
  • the winding of FIG. 7 has the median transposition point in each axial half asymmetrically displaced toward the winding midpoint.
  • the winding built in accordance with my invention may comprise more than one cylindrical layer and that the spacing of strand transposition points may be made non-uniform and progressively greater approaching each end of the winding in either one or more of such several cylindrical winding layers.
  • a conductor helically wound in at least one cylindrical layer of turns extending at constant pitch along a central axis said conductor being formed of a plurality of separately insulated strands electrically connected together at their ends and positioned in radially superposed groups forming at least two axially adjacent radially extending stacks of strands in each winding turn, the strands in ad-' jacent pairs of said stacks being radially transposed at axially spaced points along said winding layer in progressive sequence, the number of transposition points along said winding being such that each strand in each said stack occupies a succession of radially inner and radially outer positions in said stack in symmetrical sequence throughout the length of said winding, the axial spacing of said transposition points being progressively greater as said conductor approaches opposite end of said winding than is the spacing at the axial midpoint of said winding.
  • a conductor helically wound in at least one cylindrical layer of turns extending at constant pitch along a central axis said conductor being formed of a plurality of separately insulated strands electrically connected together at their ends and positioned in parallel side-by-side radially superposed relation forming at least one radial stack of strands in each Winding turn, the strands in said stack being radially transposed at at least three axially spaced apart points along the length of said winding, the median transposition point in each axially adjacent half of said winding being closer to the axial midpoint of said winding than to the adjacent end thereof.
  • a winding for electric induction apparatus wherein the strands in each said radial stack of strands are radially transposed in progressive positional sequence at axially spaced-apart points along said winding layer and the number of transposition points is such that each strand of said radial stack occupies every radially discrete strand position at least once in the course of a single traverse through said winding layer.
  • a winding for electric induction apparatus wherein the strands of said radial stack are transposed radially in progressive positional sequence at axially spaced-apart points along said winding layers, the number of transposition points being such that each strand of said radial stack occupies a succession of radially inner and radially outer positions in the stack as said conductor traverses the length of said winding, the axial spacing between said points of transposition being a minimum at the axial midpoint of said winding and being progressively greater as said conductor approaches axially opposite ends of said winding.
  • a winding for electric induction apparatus wherein said conductor consists of a single radially superposed stack of conductor strands transposed in fully inverse relationship at the axial midpoint of said winding and having a single point of transposition in each axial half of said winding positioned closer to said midpoint than to the adjacent axial end thereof.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Coils Of Transformers For General Uses (AREA)
US730169A 1968-05-17 1968-05-17 Stranded winding for high current electric apparatus Expired - Lifetime US3538473A (en)

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US (1) US3538473A (de)
CH (1) CH490729A (de)
DE (1) DE1925095C3 (de)
FR (1) FR2008740A1 (de)
GB (1) GB1261225A (de)
SE (1) SE368878B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110115601A1 (en) * 2008-06-30 2011-05-19 Coil Holding Gmbh Inductance coil for electric power grids with reduced sound emission
US20130063234A1 (en) * 2011-07-07 2013-03-14 Hypertherm, Inc. High power inductor and ignition transformer using planar magnetics
US20150170826A1 (en) * 2012-07-09 2015-06-18 Trench Limited Sound mitigation for air core reactors
WO2018007514A1 (en) 2016-07-07 2018-01-11 Abb Schweiz Ag Transformer with a winding arrangemnet of litz wires
CN107768102A (zh) * 2017-11-28 2018-03-06 国家电网公司 一种混合换位的连续式线圈及变压器
US20200058437A1 (en) * 2017-02-22 2020-02-20 Autonetworks Technologies, Ltd. Coil and reactor
US10919404B2 (en) 2017-12-19 2021-02-16 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Transformer device for a charging station for electrically charging vehicles with at least two charging points

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1629462A (en) * 1926-11-18 1927-05-17 Gen Electric Winding for electrical apparatus
GB431617A (en) * 1933-10-26 1935-07-11 British Thomson Houston Co Ltd Improvements in and relating to electric transformers
US2249509A (en) * 1939-08-31 1941-07-15 Gen Electric Rectangular cable and method of making the same
DE756929C (de) * 1940-11-23 1953-04-16 Siemens Schuckertwerke A G Wicklungsanordnung zur Beseitigung von UEberspannungen bei Stoss-beanspruchung an den Auskreuzungsstellen von Wicklungen mit mehreren parallel geschalteten Lagen fuer Transformatoren
US2710380A (en) * 1953-06-11 1955-06-07 Gen Electric Canada Winding transpositions for electrical apparatus
US2829355A (en) * 1954-04-05 1958-04-01 Gen Electric Winding transposition for electrical apparatus
BE654028A (de) * 1963-10-07 1965-02-01
US3371300A (en) * 1962-09-10 1968-02-27 Westinghouse Electric Corp Interleaved type windings for electrical inductive apparatus

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1629462A (en) * 1926-11-18 1927-05-17 Gen Electric Winding for electrical apparatus
GB431617A (en) * 1933-10-26 1935-07-11 British Thomson Houston Co Ltd Improvements in and relating to electric transformers
US2249509A (en) * 1939-08-31 1941-07-15 Gen Electric Rectangular cable and method of making the same
DE756929C (de) * 1940-11-23 1953-04-16 Siemens Schuckertwerke A G Wicklungsanordnung zur Beseitigung von UEberspannungen bei Stoss-beanspruchung an den Auskreuzungsstellen von Wicklungen mit mehreren parallel geschalteten Lagen fuer Transformatoren
US2710380A (en) * 1953-06-11 1955-06-07 Gen Electric Canada Winding transpositions for electrical apparatus
US2829355A (en) * 1954-04-05 1958-04-01 Gen Electric Winding transposition for electrical apparatus
US3371300A (en) * 1962-09-10 1968-02-27 Westinghouse Electric Corp Interleaved type windings for electrical inductive apparatus
BE654028A (de) * 1963-10-07 1965-02-01

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110115601A1 (en) * 2008-06-30 2011-05-19 Coil Holding Gmbh Inductance coil for electric power grids with reduced sound emission
US8339234B2 (en) * 2008-06-30 2012-12-25 Coil Holding Gmbh Inductance coil for electric power grids with reduced sound emission
US20130063234A1 (en) * 2011-07-07 2013-03-14 Hypertherm, Inc. High power inductor and ignition transformer using planar magnetics
US20150170826A1 (en) * 2012-07-09 2015-06-18 Trench Limited Sound mitigation for air core reactors
US9406433B2 (en) * 2012-07-09 2016-08-02 Trench Limited Sound mitigation for air core reactors
WO2018007514A1 (en) 2016-07-07 2018-01-11 Abb Schweiz Ag Transformer with a winding arrangemnet of litz wires
US20200058437A1 (en) * 2017-02-22 2020-02-20 Autonetworks Technologies, Ltd. Coil and reactor
US11557423B2 (en) * 2017-02-22 2023-01-17 Autonetworks Technologies, Ltd. Coil and reactor
CN107768102A (zh) * 2017-11-28 2018-03-06 国家电网公司 一种混合换位的连续式线圈及变压器
CN107768102B (zh) * 2017-11-28 2024-03-01 国家电网公司 一种混合换位的连续式线圈及变压器
US10919404B2 (en) 2017-12-19 2021-02-16 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Transformer device for a charging station for electrically charging vehicles with at least two charging points

Also Published As

Publication number Publication date
CH490729A (de) 1970-05-15
FR2008740A1 (de) 1970-01-23
DE1925095A1 (de) 1970-01-08
DE1925095B2 (de) 1980-11-27
SE368878B (de) 1974-07-22
DE1925095C3 (de) 1981-09-24
GB1261225A (en) 1972-01-26

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