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
  • H02K3/48—Fastening of windings on the stator or rotor structure in slots
  • H02K3/487—Slot-closing devices
• • 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
  • H01F27/288—Shielding
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K2203/00—Specific aspects not provided for in the other groups of this subclass relating to the windings
  • H02K2203/15—Machines characterised by cable windings, e.g. high-voltage cables, ribbon cables

Definitions

• the water- and oil-cooled synchronous machine described in J. Elektrotechnika is intended for voltages up to 20 kV.
• the article describes a new insulating system consisting of oil /paper insulation, which makes it possible to immerse the stator completely in oil. The oil can then be used as a coolant while at the same time using it as insulation.
• a dielectric oil-separating ring is provided at the internal surface of the core.
• the stator winding is made from conductors with an oval hollow shape provided with oil and paper insulation. The coil sides with their insulation are secured to the slots made with rectangular cross section by means of wedges.
• coolant oil is used both in the hollow conductors and in holes in the stator walls.
• Such cooling systems entail a large number of connections of both oil and electricity at the coil ends.
• the thick insulation also entails an increased radius of curvature of the conductors, which in turn results in an increased size of the winding overhang.
• the oil-cooled stator winding comprises a conventional high-voltage cable with the same dimension for all the layers.
• the cable is placed in stator slots formed as circular, radially disposed openings corresponding to the cross-section area of the cable and the necessary space for fixing and for coolant.
• the different radially located layers of the winding are surrounded by and fixed in insulated tubes. Insulating spacers fix the tubes in the stator slot.
• an internal dielectric ring is also needed here for sealing the coolant against the internal air gap.
• the design shows no tapering of the insulation or of the stator slots. The design exhibits a very narrow radial waist between the different stator slots, which implies a large slot leakage flux which significantly influences the magnetization requirement of the machine.
• the voltage of the machine can be increased to such levels that it can be connected directly to the power network without an intermediate transformer.
• the step-up transformer is thus ekminated.
• the object of the present invention is to solve this problem and thus prevent oscillations between the stator teeth. This object is achieved with the method and the device defined in the appended claims.
• Figure 2 shows an axial view of a sector in a stator core
• Figures 3 and 4 show axial views of the end of a slot situated at the air gap in the stator core, according to two embodiments of the invention
• Figure 5 shows an axial view of a sector of a stator core according to a third embodiment of the invention
• Figure 7 shows an axial section through the stator part corresponding to Figure 6, and Figures 8 and 9 show a radial and an axial view, respectively, partially in section, of the end part of the stator core near the air gap.
• a spacer or a slot wedge 11 is inserted into the opening of the slot 8.
• the wedge is made of a material which is electrically non-conducting and is non-magnetic, rigid and strong, e.g., glassfibre-reinforced plastic (epoxy plastic), and extends across the entire axial length of the stator.
• This wedge is inserted with radial force as indicated by the arrow 12 during assembly, thus providing tangentially stiff connections between the stator teeth at the air gap all round the stator. This stiff connection increases the natural frequency and offers greatly increased rigidity in each individual tooth, and even increased flexural rigidity in the whole stator core.
• the spacers 11 are wedge-shaped, as described. However, they may also be parallel-epipedic, in which case the tangentially stiff connection can be achieved in accordance with Figure 5. Adhesive joints may also be arranged between the spacers 11 and stator teeth 10, either as the sole fixing means or prior to fixing by means of tangential clamping.
• FIGS 6-9 illustrate how the slot wedges according to the invention can also be utilized to achieve axial compressive pre-stressing of the stator core 15.
• the pressure fingers 18 are arranged on each side of the core 15, immediately opposite the stator teeth 10, to act as a force-transmission device to convert the tensile force in the wedges 11 to a uniformly distributed compressive force in the stator core 15.
• the ends of the wedges are joined together by means of transverse pieces 19 which are able to cooperate with the pressure fingers 18.
• the transverse pieces 19 in the embodiment shown are joined to the wedges 11 by means of pins 20, slidable in the transverse pieces 19, which are loaded outwardly by means of a compression spring 21.
• One end of the pressure fingers 18 engages below the transverse piece 19, enabling it to load the transverse piece and thus the wedges in a direction outwards from the laminated core 15.
• the other end of the pressure fingers 18 is clamped between two devices 22 and 23 connected to the stator frame 17.
• slot wedges used for tangential positioning of the stator teeth are also utilized advantageously as tie-rods to achieve the requisite compressive stress in the stator core.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Insulation, Fastening Of Motor, Generator Windings (AREA)
• Iron Core Of Rotating Electric Machines (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=26662641

Family Applications (1)

Country Status (8)

Families Citing this family (6)

Family Cites Families (9)

• 1997
  • 1997-05-27 WO PCT/SE1997/000904 patent/WO1997045937A1/en not_active Application Discontinuation
  • 1997-05-27 BR BR9709613A patent/BR9709613A/pt not_active Application Discontinuation
  • 1997-05-27 EA EA199801057A patent/EA001098B1/ru not_active IP Right Cessation
  • 1997-05-27 CA CA 2255725 patent/CA2255725A1/en not_active Abandoned
  • 1997-05-27 EP EP97924480A patent/EP1016191A1/en not_active Withdrawn
  • 1997-05-27 AU AU29893/97A patent/AU2989397A/en not_active Abandoned
  • 1997-05-27 CN CN 97195052 patent/CN1220050A/zh active Pending
  • 1997-05-27 JP JP09542219A patent/JP2000512835A/ja active Pending

Non-Patent Citations (1)

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