Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
  • H01F41/06—Coil winding
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
  • H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
  • H01B13/26—Sheathing; Armouring; Screening; Applying other protective layers by winding, braiding or longitudinal lapping
• • 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
  • H01F27/2823—Wires

Definitions

• the present invention relates to a transposed cable for making windings in electric machines, of the type comprising a core consisting of a plurality of electric conductors of a substantially rectangular or flattened section, disposed in at least two side by side stacks and individually transposed, sequentially in the longitudinal extension of the cable, from one to the other of said stacks, and wrapping means disposed around the core to hold said conductors so as to structurally stabilize the cable.
• the invention relates to transposed cables to be employed in low-voltage windings of electric transformers or, more generally, in making windings in electric machines submitted to high intensity but relatively low voltage currents, so that, to dispose them in the winding, a high electric insulation between the coils forming the winding itself is not required.
• transposed cables usually employed in making electric windings in transformers and the like, essentially comprise a core consisting of a plurality of conductors of a substantially rectangular section, usually referred to as "flattened wires", currently made of copper and individually coated with one or more layers of electrically insulating paint .
• These flattened wires are currently disposed in mutually superposed relationship so as to form two stacks arranged side by side relative to each other.
• each flattened wire has a slightly inclined path so that it will progressively take up all positions between the base and the top of the stack to which it belongs .
• each flattened wire is diverted onto the adjacent stack so as to successively take all positions included between the base and the top of the latter. Consequently, in the longitudinal cable extension, each flattened wire progressively takes all positions within the section of said cable.
• wrapping means usually consisting of one or more paper ribbons helically wound around the core itself so as to form partly overlapped turns.
• wrapping means usually consisting of one or more paper ribbons helically wound around the core itself so as to form partly overlapped turns.
• pores in the covering material are provided with a size of from 0.2 to 10 mm , the area occupied by the pores being from 20 to 80% of the overall area of the covering material .
• the core wrapping can be advantageously carried out either by helical winding, around the core itself, of a continuous thread-like element or by a plurality of continuous thread-like elements helically wound in the same direction or in opposite directions, but not interlaced with each other.
• transposed cable for making windings for electric machines, characterized in that said wrapping means comprise at least one or more thread-like elements helically wound around the core, substantially in the absence of points of mutual interlacing.
• two or more thread-like elements can be provided which are disposed parallel to each other and wound in sequentially alternated turns, or helically wound in respectively opposite directions.
• each thread-like element can be made in the form of a single thread of a diameter of from 0.1 to 0.8 mm, or in a flattened form of the same strength, with a width of from 0.30 to 0.60 mm.
• each of said thread-like elements is formed of a polyester yarn of a size of from 1000 to 3000 dtex.
• each thread-like element has a tensile strength at break between 50 and 250 N, and an elongation at break between 5 and 20%.
• each thread-like element is wound with a tension of from 5 to 25 N, with a winding pitch between 0.5 and 3 times the cable width, and/or in such a manner that the turns formed by said one or more thread-like elements on the core are mutually spaced by an amount, measured perpendicularly to the thread-like element direction of extension, equal to the pitch divided by the number of thread-like elements, or, alternatively, at least equal to six times the dimension of the thread-like element measurable in the same direction.
• At least one tearable ribbon-like element preferably of paper material, may be advantageously arranged on the cable in reference, said ribbon-like element being helically wound around said conductors and said at least one thread-like element.
• At least one tear thread may also be provided, extending longitudinally along the cable between the paper ribbon and said at least one thread-like element, said tear thread being arranged to be pulled along away from the cable to cause tearing and removal of the tearable ribbon-like element.
• At least one adhesive tape may be applied longitudinally along the cable on the outside of the tearable ribbon-like element, to keep turns joined together when said ribbon-like element is torn and removed from the cable .
• It is a further object of the invention a process for manufacturing a transposed cable to be employed for making windings in electric machines comprising the following steps: making a core formed of electric conductors of flattened section disposed in at least two side by side stacks and individually transposed from each other of said stacks, sequentially in the longitudinal cable extension; covering said core with wrapping means disposed around the core for holding the individual conductors, so as to cause a structural stabilization of the core, characterized in that said covering step is carried out by helically winding one or more thread-like elements substantially in the absence of mutual interlacing points.
• the covering step comprises winding of a continuous thread-like element; alternatively, it can be carried out by helically winding at least two continuous thread-like elements disposed either parallelly or in opposite winding directions.
• a tension of from 5 N to 25 N is applied to each thread-like element, and winding of said one or more thread-like elements is carried out in such a manner that turns are spaced apart from each other by the same distance according to a value included between 0.5 and three times the cable width.
• a step involving helical winding of at least one tearable ribbon-like element around the core carrying said at least one thread-like element may be also carried out.
• provision may be also made for insertion of a tear thread extending longitudinally between said at least one tearable ribbon-like element and the core carrying said at least one thread-like element .
• Insertion of said tear thread is preferably carried out by pulling the thread itself by means of the cable moving forward to a winding station conveniently arranged for carrying out winding of the tearable ribbon-like element.
• the process according to the invention preferably also provides for application of at least one adhesive tape externally of the tearable ribbon-like insert wound over the cable .
• the invention further proposes a new method of making an electric winding by means of a transposed cable, said cable comprising a core made up of a plurality of electric conductors of flattened section disposed in at least two side by side stacks and individually transposed from each other of said stacks, sequentially in the longitudinal cable extension, at least one tearable ribbon-like element helically wound around said core, said method being characterized in that during winding of the cable around the core, removal of the tearable ribbon-like element is carried out by pulling at least one tear thread laterally of the core, said tear thread being arranged longitudinally along the cable between said tearable ribbon-like element and said core.
• the tear thread is pulled in correspondence with an extension length of the cable comprised between the winding core and the braking means acting on the cable to give it a desired tensioning.
• transposed cable in particular for making windings in electric machines, in accordance with the present invention, as well as of a manufacturing process of same and a method of making a winding by said transposed cable.
• Fig. 1 is a perspective view of a transposed cable made in accordance with the present invention, with an auxiliary paper covering partly removed;
• Fig. 2 is a diagrammatic plan view of a production line of the transposed cable in accordance with Fig. 1 ;
• FIG. 3 is a diagrammatic top view of a winding step of the transposed cable in accordance with the invention with simultaneous removal of the auxiliary paper covering in order to make a winding for an electric machine.
• transposed cable in particular for making windings in electric machines in accordance with the present invention has been generally identified by reference numeral 1.
• the transposed cable 1 has a core 2 comprising a plurality of flattened wires 3, i.e. conductors made of copper or another electrically-conductive appropriate material, of a substantially rectangular flattened section and individually coated with an electrically insulating paint, not shown in the accompanying drawings.
• a core 2 comprising a plurality of flattened wires 3, i.e. conductors made of copper or another electrically-conductive appropriate material, of a substantially rectangular flattened section and individually coated with an electrically insulating paint, not shown in the accompanying drawings.
• the flattened wires are disposed in mutual superposed relationship in a first and a second stack 4a, 4b respectively arranged side by side, optionally alternated with a partition insert 5 made of paper or another appropriate material .
• Each flattened wire 3 substantially lies in a plane perpendicular to the separation plane between the two stacks 4a, 4b and extends following a slightly inclined path so as to occupy, progressively along the cable extension 1, all the positions within the corresponding stack 4a, 4b.
• the path of each flattened wire 3 is diverted onto the adjacent stack 4b by a transposed length 3a intersecting the separation plan between the stacks 4a, 4b.
• the flattened wire 3 which is transposed from the first stack 4a to the second stack 4b extends obliquely until it reaches the opposite end of the new stack 4b, to be again diverted onto the adjacent stack 4a.
• Cable 1 further comprises wrapping means 6 disposed around the core 2 to hold the flattened wires 3 so as to obtain a certain structural stabilization of cable 1, thereby conveniently inhibiting undesired movements of flattened wires 3 in a radial direction relative to the geometric axis "X" of the cable.
• This wrapping means 6 comprises one or more thread-like elements 6a, 6b helically wound around core 2.
• each thread-like element 6a, 6b consists of a single thread made of polyester, rayon, polypropylene, PPS (polyphenylene sulfide) , PCDA (polycyclohexanedimethyleneterephthalate) , having approximately a diameter of from 0.1 to 0.8 mm and preferably from 0.3 to 0.6 mm.
• Microtapes may also be used, namely thread-like elements of flattened section and equivalent strength, of a width preferably between 0.2 and 1 mm, made of the above materials; microtapes of polyester, polypropylene, PPS, PCDA may be for example used, which have sections of from 0.2 mm x 0.4 mm to 0.4 mm x 0.6 mm, depending on the desired strength features.
• each thread-like element 6a, 6b should have a tensile strength at break of from 50 to 250 Newton and an elongation at break between 5 and 20%.
• the number of thread-like elements 6a, 6b to be used may vary depending on requirements, and basically the greater is the number of flattened wires 3 forming core 2, the greater is the number of these thread-like elements .
• a single thread-like element 6a can be used, which is wound with a winding pitch of from 0.5 to 3 times the cable width, to obtain a sufficient holding for flattened wires 3.
• two thread-like elements 6a, 6b may be advantageously applied. These thread-like elements can be disposed parallel to each other, or wound in respectively opposite directions, as shown in the example of Fig. 1.
• two or more pairs of thread-like elements 6a and 6b can be arranged which are wound respectively in opposite directions.
• thread-like element or elements 6a, 6b should be devoid of points of mutual interlacing at the relevant crossing points. This can be easily viewed from Fig. 1 where the second thread-like element 6b is merely superposed on the first thread-like element 6a at their crossing point .
• the winding pitch of the individual thread-like elements preferably ranges from 0.5 to 3 times the cable width and each of the turns they form is spaced apart from the immediately adjacent turns by a distance equal to the pitch divided by the number of the thread- like elements.
• the distance between two adjacent turns measured perpendicularly to the extension of the thread-like element 6a, 6b should be at least equal to 6 times the diameter or size of the thread-like element itself measured in the same direction.
• the transposed cable 1 is further provided with at least one tearable ribbon-like element 7 helically wound around core 2 and thread-like elements 6a and 6b constituting the wrapping means 6, said ribbon-like element being superposed to said wrapping means.
• the ribbon-like element is preferably made of a paper of "clupack” or "kraft” type with a thickness included approximately between 0.05 and 1.15 mm.
• the tear thread 8 can be pulled laterally away from the cable core 2 to cause tearing and removal of the tearable ribbon-like element 7, as better clarified in the following, during the step of winding the cable 1 over a relevant winding core .
• At least one adhesive tape 9 is also provided, applied longitudinally to the cable 1 externally of the tearable ribbon-like element 7.
• This adhesive tape 9 enables turns formed by the tearable ribbon-like element 7 to be maintained together, so as to avoid an uncontrolled dispersion of said turns when the tape is torn and removed from the cable by means of the tear thread 8.
• a transposition unit 14 operates, cyclically intervening on the individual flattened wires 3 located at the base and on top of columns or stacks 4a, 4b to cause transposition from each other of said columns.
• Core 2 coming from the transposition unit 14 is moved longitudinally through a series of winding stations by which application of the wrapping means 6 and the tearable ribbon-like element takes place.
• a first winding station 15 is contemplated where winding of the first thread-like element or elements 6a is provided, preferably according to a winding tension included between 5 N and 25 N.
• a second winding station 16 Operating downstream of the first winding station 15 is a second winding station 16 carrying out application of the second thread-like element or elements 6b, in the same direction as the first thread-like elements 6a or in the opposite direction, the latter being in superposition relationship with the former at the respective crossing points.
• a third winding station 17 may be utilized, if necessary, for application of further thread-like elements .
• a fourth winding station 18 is finally provided to carry out winding of the tearable ribbon-like element 7 superposed on the wrapping means 6 consisting of the thread-like elements 6a and 6b.
• a feed and guide unit 19 is disposed for the tear thread 8, said thread being guided in correspondence to the cable entering the fourth winding station 18, so that the tear thread is laid down lengthwise on the cable externally of the wrapping means 6, to be engaged between the latter and the tearable ribbon-like element 7 wound in the fourth winding station 18.
• a unit 20 to apply an adhesive tape which, by means of suitable guide means, applies the adhesive tape 9, continuously supplied from a roll 9a, to the exterior of the tearable ribbon-like element 7.
• a dragging unit 21 located also downstream of the winding stations 15, 16, 17, 18, operates on the finished cable 1 to cause dragging of the latter in a longitudinal direction along the whole production line, and feeding of the cable itself to a collecting reel 22 located at the end of the production line.
• the tear thread 8 is pulled laterally of the cable 1 and optionally collected on a spool 25, concurrently with moving forward of the cable to the winding core 23. Consequently, the tearable ribbon-like element 7 is torn lengthwise of cable 1.
• Cable 1 wound around winding core 23 is therefore devoid of any paper ribbon.
• the presence of the thread-like elements 6a, 6b wound around core 2 ensures an excellent structural stability of cable 1, keeping the individual flattened wires 3 conveniently guided in their mutual slidings, such slidings being required so that the different radii of curvature according to which the radially outermost flattened wires are wound relative to the radially innermost flattened wires 3 may be followed, without any risks of undesired deformations and/or displacements of the individual flattened wires 3 away from the cable 1 axis.
• the invention enables a better cooling of the winding core consisting of the cable itself.
• the paper covering in accordance with the known art will substantially perform the only function of structurally holding the cable core and mechanically protecting the same while it is being unwound, without practically performing any function of electric insulation, differently from that which happens, on the contrary, in high-voltage windings or windings of different typology.
• the presence of the thread-like wrapping element or elements 6a, 6b does not at all hinder passage of oil or other cooling fluid in intimate contact with the individual flattened wires 3, thereby enabling an efficient heat removal.
• the core wrapping made in accordance with the present invention further enables a better dimensional definition of winding 26 with respect to wrappings made of paper or net-like ribbons.
• ribbons of paper material or net-like ribbons leave empty spaces between the ribbons and flattened wires, above all at transposed segments.
• the cable wrapping paper or ribbons cause dimensional unreliability, because, firstly, dimensions of the empty spaces depend on different variable factors such as ribbon-winding modalities, ribbon tensioning during winding, and geometric features of the cable.
• these empty spaces can be eliminated or in any case reduced in an unspecified manner only by pressing winding 26 before or during heat treatments performed during production phase of the latter. Therefore, it is impossible to know in advance the exact dimensional features of the finished winding 26.
• the cable wrapped with thread-like elements 6a, 6b supplies repeatable and easily verifiable dimensions, thereby avoiding dimensional correction measures a posteriori .
• the higher dimensional accuracy of the cable allows a remarkable size reduction of the finished winding 26, namely a better filling factor expressed as ratio between the volume occupied by copper or other material forming flattened wires 3 and the overall volume of winding 26.
• a better filling factor expressed as ratio between the volume occupied by copper or other material forming flattened wires 3 and the overall volume of winding 26.
• the invention appears to be an improvement also with reference to known cables wrapped with net-like ribbons, which have higher production costs as compared with the thread-like elements employed in accordance with the present invention.
• Wrapping with net-like ribbons further causes the use of a greater amount of material to perform wrapping, and consequently a reduction of heat removal from flattened wires.
• the cable in accordance with the present invention can be used in any other circumstances when current values for which the cable is designed do not make it necessary the presence of an electric insulating layer of paper material.
• tearable ribbon-like insert may be advantageously used also in cables having a wrapping consisting of net -like ribbons or completely devoid of wrapping, as well as in any circumstances when it is desirable to protect the cable from mechanical stresses or weathering agents or from the attack of other substances present in the environment with which the cable may be brought into contact during transportation and/or storage, as well as during the step involving manufacturing of winding 26.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Insulated Conductors (AREA)
• Manufacture Of Motors, Generators (AREA)
• Storage Of Web-Like Or Filamentary Materials (AREA)
• Processes Specially Adapted For Manufacturing Cables (AREA)
• Manufacturing Of Electric Cables (AREA)
• Manufacturing Cores, Coils, And Magnets (AREA)
• Paper (AREA)
• Electric Cable Installation (AREA)
• Control Of Velocity Or Acceleration (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Country Status (13)

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Citations (3)

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• 1997
  • 1997-02-13 IT IT97MI000292A patent/IT1290307B1/it active IP Right Grant
• 1998
  • 1998-02-06 ES ES98102034T patent/ES2224298T3/es not_active Expired - Lifetime
  • 1998-02-06 EP EP98102034A patent/EP0859381B1/en not_active Expired - Lifetime
  • 1998-02-06 DE DE69824770T patent/DE69824770T2/de not_active Expired - Fee Related
  • 1998-02-06 AT AT98102034T patent/ATE270462T1/de not_active IP Right Cessation
  • 1998-02-12 WO PCT/EP1998/000789 patent/WO1998036431A1/en active IP Right Grant
  • 1998-02-12 CZ CZ0285099A patent/CZ297435B6/cs not_active IP Right Cessation
  • 1998-02-12 TR TR2000/02025T patent/TR200002025T2/tr unknown
  • 1998-02-12 PL PL98335820A patent/PL186734B1/pl not_active IP Right Cessation
  • 1998-02-12 HU HU0000879A patent/HU223014B1/hu not_active IP Right Cessation
  • 1998-02-12 BR BR9807336-2A patent/BR9807336A/pt active Search and Examination
  • 1998-02-12 TR TR2000/02024T patent/TR200002024T2/tr unknown
  • 1998-02-12 JP JP53534598A patent/JP2001511939A/ja not_active Ceased
  • 1998-02-12 TR TR1999/01938T patent/TR199901938T2/tr unknown
• 1999
  • 1999-08-12 NO NO19993902A patent/NO321392B1/no not_active IP Right Cessation

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