Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1998-09-29
2001-08-07
Enad, Elvin (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S062000, C310S063000, C310S065000, C310S260000
Reexamination Certificate
active
06271608
ABSTRACT:
This is a continuing application of International Application No. PCT/GB97/00931 filed on Apr. 1, 1997.
This invention relates to an alternating current machine and more particularly although not exclusively to an AC generator.
An alternating current machine comprises a rotor journalled for rotation within a stator comprising stator windings which are gathered together into an annular array at either end of the stator. The stator windings may be perfect lap windings or perfect concentric windings. Either way they comprise bundles of generally parallel conductors which are led from end to end of the stator and turned around at either end so as to be led back along the length of the stator. The bundles of conductors are led from end to end of the stator along generally parallel paths and form pairs of terminal leads at either end, the terminal leads being taken from one end of the stator to neutral and power output terminals of the machine to which they are connected.
If the terminal leads are bunched together as a solid mass, problems with hot spots arise. Also difficulties arise which cause the terminals to which terminal leads are connected to be located well spaced from the axis of rotation of the rotor. In practice there is no insulation between those terminals and the annular array of stator windings of the machine as is shown in DE-A-1144382.
U.S. Pat. No. 5,175,458 discloses an assembly for carrying stator terminal leads to a terminator to which an electrical connection can be made. The alternator for which this assembly is designed is relatively small. The assembly comprises an arcuate, or horseshoe-shaped member which is fitted to the appropriate end of the stator. The horseshoe-shaped member is solid and has three circumferentially extending channels defined in its outer surface. Each channel receives a terminal lead which is an extension of a stator winding and leads that terminal lead along the circumferentially extending track it forms to the terminator to which it is connected. The channels are axially spaced from one another. This arrangement would suffer from cooling problems if it were to be used in large alternating current machines because the terminal leads would be shielded from cooling air flow through the stator.
According to one aspect of this invention there is provided an alternating current machine as claimed in claim
1
. Preferred features of that alternating current machine are claimed in claims
2
.
DE-A-1144382 illustrates an arrangement of output terminals of an alternating current machine to which stator winding terminal leads may be connected. Each terminal to which such a terminal lead is connected is supported by a metal angle member to which it is riveted. The angle members are spaced from one another and are mounted at either end on a support fixed to the casing through a respective insulator. The electromagnetic forces that can be generated under fault conditions, such as sudden or sustained short circuit faults externally imposed on the machine by the power transmission or distribution system to which it may be connected, can cause the angle members to which the terminals are riveted to twist and in the extreme case, cause adjacent terminals to contact one another with undesirable consequences.
FR-A-2693848 disclose a mounting for distribution busbars in which the busbars are clamped between elongate mouldings which fill spaces between faces of adjacent busbars. The mouldings have a uniform cross-section with flat sides which are in face to face abutment with the faces of the busbars. Gaps remain between the edges of adjacent busbars and adjacent mouldings since the mouldings are spaced from one another by the thickness of the busbars. The stack of mouldings and busbars is clamped by nuts fitted to the ends of screws which extend through the gaps and through aligned holes in the mouldings.
It is desirable to arrange the busbars of the terminal arrangement of a three phase machine so that the leads can be connected to their positions below the structural panel permanently and adjustment between a series star connection and parallel star connection can be made from above the structural panel without altering the connection of the leads below. This is achieved by providing for each of the three power output busbars and the respective neutral busbars, a respective pair of spaced busbars which extend through the structural panel in substantially the same way as the neutral and power output busbars between which they are located. Each such respective pair of spaced busbars are connected together by a suitable link above the structural panel for a series star connection. On the other hand, one busbar of each such respective pair is connected to the adjacent neutral busbar and the other busbar of the respective pair is connected to the adjacent power output busbar for a parallel star connection, such connections between the busbars being made by suitable links above the structural panel.
The rotor of an alternating current machine may carry a fan at the end of the stator remote from the terminal leads. The fan would be operable to draw air through the stator from the remote end thereof in order to cool the stator windings.
DE-A2526532 discloses such a rotor and fan arrangement. The fan is within a casing which cooperates with it to provide a conduit for discharge of air flow from the fan, the conduit being in the form of a volute whereby its area increases progressively in the downstream direction. Although such use of a volute casing improves the cooling by increasing the volume of air that is drawn through the stator by the fan for discharge through the discharge passage formed by the volute casing, even more cooling is desirable.
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Research Disclosure, No. 342, Oct. 1992, p. 762, XP000326659 “Connection of Induction Motor Stator Neutral Wires to a Common Bus Ring With Copper ARC Spray/Plasma Spray Techniques”.
International Search Report, Jul. 8, 1997.
Bean John Ernst Clive
Haydock Lawerence
Wyles Peter John
Dang Dinh Le
Enad Elvin
Gron Gary M.
Newage International Limited
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