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Publication numberUS2978530 A
Publication typeGrant
Publication dateApr 4, 1961
Filing dateMay 28, 1959
Priority dateJun 2, 1958
Publication numberUS 2978530 A, US 2978530A, US-A-2978530, US2978530 A, US2978530A
InventorsFernand Braeckman
Original AssigneeAcec
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Conductor for transformer windings
US 2978530 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

April 4, 1961 F. BRAECKMAN 2,978,530

CONDUCTOR FOR TRANSFORMER wmnmcs Filed May 28, 1959 United States Patent CONDUCTOR FOR TRANSFORMER WINDINGS Fernaud Braeckman, Nalinnes, Belgium, assignor t9 Ateliers de Constructions Electriques de 'Charlerol, Brussels, Belgium, a corporation of Belgium Filed May 28, 1959, Ser. No. 816,468

Claims priority, application France June 2, 1958 1 Claim. (Cl. 17434) The invention relates to a special type of conductor for windings of transformers and similar apparatus.

It is shown that, in power transformers, and apparatuses comprising similar arrangements, the conductors forming the windings, being submitted to the stray field, give rise to extra losses.

Figure 1 shows, as an example, an horizontal cut through a classic interleaved transformer made up from disc coils, showing a high voltage winding HT between two low voltage windings BT.

If one considers, for example, a flux line L of the stray field passing through the low voltage winding ET, the field F, at any point may be split up into an axial component F and a radial component F,. The extra losses developed in the conductors by these two components are proportional to the square of the field strength and to the square of the conductor dimensions.

The tendency to increase continuously the rating of the power transformers, leads to an ever increasing space filling factor, resulting in always higher flux densities.

Hence the reduction of the extra losses is of paramount importance. Several solutions to this problem are known.

Among these, one is currently used in transformer manufacture, and consists in winding up coils from subdivided insulated conductors which are interleaved during the winding operation.

Figure 2a presents, for example, a half out through a turn of a disc coil, the axis of which is shown as XX.

This turn is built up from three bundles comprising each three strands A, B, C, all being connected in parallel.

At a conveniently situated place of the coil, generally towards the middle, strands A and B interchange their position so that, on the average, these conductors will be submitted to a radial field corresponding to the one encountered at half thickness of the coil (it may be assumed that the radial field component varies linearly across the coil as shown in Figure 2b). In this Way the electromotive force induced in the various individual strands by the radial component of the flux, is roughly the same and they may be connected in parallel without any undue circulating current.

A further step is to compensate not only for the efiect of the radial flux F,, but as well for the axial component of the flux F,,. For example, Figure 3 presents a half cut through a turn, the axis of which is shown as XX, and incorporating nine strands A A A B B B C C C operated in parallel. Crossovers are applied not only in the coil itself among the strands from the same 2,978,536 Patented Apr. 4, 1961 bundle, but as well among the bundles themselves. This set up is used principally for low voltage windings and tapping coils.

If one wishes to reduce even more the eddy losses, it is necessary to reduce the dimensions of the conductors to the minimum possible size but there is a limit to this due to taping and winding difiiculties.

A solution to this is brought by our invention where the conductor is constituted in such a way that a marked reduction in extra losses is achieved. This conductor is made up from a cable comprising concentrically disposed strands twisted all in the same direction; said strands being formed by wires of small circular section insulated by enamel or any other suitable thin insulating material; strands from even layers are twisted in one way while those from odd layers are twisted the other; the cable so formed is then shaped to a rectangular cross section by pressing.

Figure 4 shows as a non-limitative example, a conduc tor incorporating the embodiments of the invention. It is made up from strands such as 1, 2 and 3, set in concentric layers. All these strands are twisted in the same direction and are formed by round Wires 4; said wires being of small cross section, enamel insulated and twisted in the way shown by arrows. Direction of twisting is alternated in each successive layer.

Figure 5 shows, diagrammatically, how the cable appears after having been formed into a rectangular cross section. Direction of twisting of the wires within the strands, is shown by arrows as in Figure 4. The conductor so formed may then be insulated, as commonly known in the art, by a material 5.

In a winding turn made up from a conductor as described in the invention, each of the wires 4 occupies all possible positions radially and axially and hence they are all submitted to the same average stray field.

I hereinafter claim as my invention:

An electrical conductor of rectangular cross-section comprising a plurality of strands arranged in a plurality of concentric, successive layers, said strands comprising electrically conductive wires helically twisted together in a common direction within respective strands in a given layer and twisted in opposite directions in alternate layers, insulation on each of said wires comprising a thin insulative coating, all of the strands in said conductor being helically twisted together in the same direction with the pitch of the helical twist being so chosen that the wires of two successive layers do not cross each other thereby to avoid damaging said thin insulative coating and preclude formation of short-circuited loops in the conductor.

References Cited in the file of this patent UNITED STATES PATENTS 297,177 Shelboume Apr. 22, 1884 587,764 Short Aug. 10, 1897 1,904,162 Milliken Apr. 18, 1933 2,081,427 Firth et a1 May 25, 1937 FOREIGN PATENTS 309,596 Great Britain Feb. 20, 1930 855,005 France Apr. 30, 1940

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US297177 *Apr 22, 1884 shelbourne
US587764 *Aug 10, 1897 Wire for armature-windings
US1904162 *Aug 13, 1930Apr 18, 1933Humphreys MillikenElectrical cable
US2081427 *Feb 16, 1935May 25, 1937Bell Telephone Labor IncElectric communication cable
FR855005A * Title not available
GB309596A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3283280 *Dec 22, 1964Nov 1, 1966Westinghouse Electric CorpTransposition for electrical conductors
US4176905 *Aug 1, 1978Dec 4, 1979Societe d'Exploitation des Procedes Marechal SEPMFlexible electrical contact
US4431860 *May 24, 1982Feb 14, 1984Westinghouse Canada Inc.For use in an electrical apparatus
US4439256 *Feb 18, 1981Mar 27, 1984New England Electric Wire CorporationConductor core of copper or aluminum
US4538023 *Dec 30, 1983Aug 27, 1985Brisson Bruce AAudio signal cable
US4640983 *Apr 8, 1985Feb 3, 1987Institut Straumann AgConductor device, particularly for at least partial insertion in a human or animal body, comprising a spiral formed from at least one conductor
US4731506 *Oct 29, 1986Mar 15, 1988Noel LeeSignal cable assembly
US4734544 *Oct 29, 1986Mar 29, 1988Noel LeeSignal cable having an internal dielectric core
US4743712 *Mar 30, 1987May 10, 1988Noel LeeSignal cable assembly with fibrous insulation and an internal core
US4777324 *Mar 30, 1987Oct 11, 1988Noel LeeSignal cable assembly with fibrous insulation
US4829417 *Jul 9, 1987May 9, 1989Siemens AktiengesellschaftHigh-power transformer
US4859978 *Apr 29, 1988Aug 22, 1989Electric Power Research Institute, Inc.High-voltage windings for shell-form power transformers
US4864266 *Nov 29, 1988Sep 5, 1989Electric Power Research Institute, Inc.High-voltage winding for core-form power transformers
US4912446 *Jun 29, 1987Mar 27, 1990Westinghouse Electric Corp.High energy density hyperconducting inductor
US5483022 *Apr 12, 1994Jan 9, 1996Ventritex, Inc.For at least partial insertion in a human/animal body
US5508674 *Sep 22, 1993Apr 16, 1996Electric Power Research Institute, Inc.Core-form transformer
US6452101 *Aug 6, 1999Sep 17, 2002Hitachi, Ltd.Multi-core conductive wire and a method of manufacturing the same
US6649844 *Feb 16, 2001Nov 18, 2003Mitsunishi Denki Kabushiki KaishaCoil conductor for dynamoelectric machine
US7262537 *Jul 19, 2002Aug 28, 2007Hamilton Sundstrand CorporationElectric motor and generator component having a plurality of windings made from a plurality of individually conductive wires
US7863795 *Jan 31, 2008Jan 4, 2011Alstom Technology LtdMethod for producing a conductor bar of transposed stranded conductors
USRE33750 *Oct 4, 1988Nov 26, 1991 Signal cable assembly
DE2305957A1 *Feb 7, 1973Aug 15, 1974Siemens AgTransformator fuer schaltnetzteile
DE2741257A1 *Sep 14, 1977Mar 23, 1978Marechal SepmNachgiebiger elektrischer druckkontakt
EP0030580A1 *Dec 3, 1979Jun 24, 1981ETAT-FRANCAIS représenté par le DELEGUE GENERAL POUR L'ARMEMENTDevice for electric ignition by magnetic induction of a pyrotechnic substance
EP0092018A1 *Apr 21, 1982Oct 26, 1983Spezielektra Esslinger K.G.Reactor, particularly air isolated reactor without magnetic core
EP0118390A1 *Jan 30, 1984Sep 12, 1984Siemens AktiengesellschaftStranded conductor for flexible electrical cables
EP0119155A1 *Jan 30, 1984Sep 19, 1984Siemens AktiengesellschaftStranded conductor for flexible electrical cables and method of manufacturing it
EP1655740A1 *Aug 5, 2004May 10, 2006Soshin Electric Co. Ltd.Stranded wire, coil using this wire, noise filter device having this coil, and production method for stranded wire
WO1988003318A1 *Oct 20, 1987May 5, 1988Noel LeeImproved signal cable assembly
WO1988007749A1 *Oct 20, 1987Oct 6, 1988Noel LeeSignal cable assembly with fibrous insulation
WO1990006584A1 *Sep 5, 1989Jun 14, 1990Electric Power Res InstHigh-voltage winding for core-form power transformers
WO1995015569A1 *Nov 24, 1994Jun 8, 1995Asta Elektrodraht GmbhTwisted conductor
Classifications
U.S. Classification174/34, 174/128.1, 174/129.00R, 174/119.00R
International ClassificationH01B5/00, H01B5/08, H01F27/28, H01B13/02
Cooperative ClassificationH01B13/02, H01F27/2823, H01F2027/2838, H01B5/08
European ClassificationH01F27/28B, H01B13/02, H01B5/08