Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K3/00—Details of windings
  • H02K3/46—Fastening of windings on the stator or rotor structure
  • H02K3/50—Fastening of winding heads, equalising connectors, or connections thereto
  • H02K3/505—Fastening of winding heads, equalising connectors, or connections thereto for large machine windings, e.g. bar windings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/308—Wires with resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/40—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes epoxy resins

Definitions

• the present invention relates to a structure for blocking heads of stator windings of electrical machines, in particular of electric generators, and to a method for blocking heads of stator windings of electrical machines, in particular of electric generators.
• the heads of the windings of a stator (end windings) of an electric generator (or other electrical machine) are the terminal portions of the stator bars that extend from the stator core.
• Said heads must be appropriately supported and blocked, as well as electrically insulated, and various systems are known for providing the mechanical insulating anchorage for the heads.
• ties around the heads the ties being formed by cords or tapes made of fibreglass englobed in polymeric resins, specifically epoxy resins, polyester resins, or mixtures thereof.
• An object of the present invention is to provide a structure and a method for blocking heads of stator windings of electrical machines, in particular of electric generators, that will be free from the drawbacks of the known art highlighted herein.
• an object of the invention is to provide an alternative structure and method for providing the insulated mechanical anchorage of the heads of the stator windings via ties impregnated with resin in a simple, fast, and effective way .
• an object of the invention is to provide the ties without resorting to polymeric compositions comprising solvents in such a way as to shorten the polymerization times and reduce safety risks and environmental problems.
• a further object of the invention is to make it possible to ascertain in a simple and precise way complete polymerization of the resin in such a way that the electrical tests following upon formation of the ties are always conducted in safety conditions, minimizing the risks of electrical discharges that might cause damage.
• the present invention relates to a structure and a method for blocking stator end windings of electrical machines, in particular of electric generators, as defined in basic terms in the annexed Claim 1 and Claim 9, respectively, as well as, for the preferred additional features, in the dependent claims.
• the blocking structure according to the invention is made with a polymeric system (comprising one or more base resins) having the following characteristics:
• FIG. 1 is a partial schematic view of a terminal region of an electrical machine provided with a structure for blocking the heads of the stator windings made according to the invention.
• the annexed figure is a schematic and partial illustration of a terminal region of an electrical machine 1, in particular an electric generator, having a stator 2 and a rotor 3 housed within the stator.
• the stator 2 comprises a stator core 4, extending from which are stator bars 5 provided with windings 6 and with respective heads 7 of the windings (end windings) .
• the stator core 4 has a circumferential flange 8 connected to a support 9.
• the heads 7 of the windings are tied together and/or anchored mechanically to the support 9 via an insulated blocking structure 10, which comprises a plurality of ties 11 formed by tie elements 12, in particular made of fibreglass, impregnated with a polymeric system.
• the tie elements 12 are, for example, cords, tapes, bands, etc., made of fibreglass, wound around the heads 7 of the windings and/or engaging holes and/or hooks 13 on the support 9.
• the polymeric system comprises a bi-component resin, formed by at least one polymeric base resin and at least one curing/polymerizing agent, and at least one chromatic additive sensitive to polymerization; preferably, the polymeric system is basically constituted by the components indicated; in particular, the polymeric system does not include solvents for the base resin nor solvents in general.
• the term "base resin” indicates a resin or a mixture of resins.
• the base resin is advantageously a modified epoxy resin free from solvents, which polymerizes in the presence of the curing/polymerizing agent, which is preferably an amine curing agent.
• the base resin is a glycidyl-epoxy resin and more precisely a glycidyl-ether epoxy resin, for example of the DGEBA (di-glycidyl-ether of bisphenol A) type.
• the curing agent is an aliphatic-amine-based agent.
• the bi-component resin i.e., the base resin and the curing agent
• the base resin and the curing agent is a resin with low viscosity (also at room temperature) and is free from solvents, and changes colour following upon polymerization thanks to the presence of the chromatic additive.
• the polymeric system has a viscosity lower than approximately 400 cP at room temperature.
• the bi-component resin polymerizes at room temperature at a controlled and relatively slow rate in such a way as to enable impregnation of the tie elements.
• the polymeric system (formed by the base resin, the curing/polymerizing agent, and the chromatic additive) has a pot-life at room temperature of approximately 6 hours (maximum viscosity 3000 cP) and reaches complete polymerization, once again at room temperature, in approximately 48 hours.
• the polymeric system and specifically the base resin changes colour as a result of the chromatic additive, which is an additive sensitive to the polymerization density, preferably with a prevalently inorganic base.
• the chromatic additive is able to change the colouring of the resin when polymerization of the resin is practically complete.
• formulations of the polymeric system are the following:
• a first container is provided containing the base resin and a second container is provided containing the curing/polymerizing agent and the chromatic additive in the due weight proportion.
• tie elements 12 for example, cords
• these are prepared so that they have the necessary length.
• the tie elements 12 there are mixed together and stirred, for example in a third container with stirrer, the contents of the first and second containers, to form the complete polymeric system.
• tie elements 12 are impregnated with the polymeric system, for example by being dipped in the third container.
• the impregnated tie elements 12 are then used for tying the heads 7 of the windings appropriately to form the ties 11 and the structure 10 as a whole.
• the tie elements 12 not impregnated are first used for tying the heads 7 of the windings, and then the elements 12 installed are impregnated with the polymeric system, for example by injection of the polymeric system with the aid of purposely provided implements (for example, syringes), in a number of points of the ties 11.
• purposely provided implements for example, syringes
• the colouring of the resin helps to verify proper impregnation of all the ties 11.
• the resin has a certain colouring.
• the resin and the polymeric system as a whole assume a different colouring, which indicates visually to the operators that polymerization is complete. After the change in colour has been noted, the operators can carry out the customary voltage tests.

Landscapes

• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Manufacture Of Motors, Generators (AREA)
• Synchronous Machinery (AREA)
• Insulation, Fastening Of Motor, Generator Windings (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

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Family Cites Families (4)

• 2010
  • 2010-10-18 IT ITMI2010A001904A patent/IT1402046B1/it active
• 2011
  • 2011-10-18 EP EP11805188.7A patent/EP2630720A2/de not_active Withdrawn
  • 2011-10-18 WO PCT/IB2011/054642 patent/WO2012052928A2/en not_active Ceased

Non-Patent Citations (1)

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