Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-04-24
2001-05-01
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C029S605000
Reexamination Certificate
active
06225726
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to turbine generators and more particularly to a clamping apparatus for clamping of stator coil windings within a turbine generator.
BACKGROUND OF THE INVENTION
Turbine generators for producing electric power are well known and typically include an end winding portion that includes a stator core having several slots that receive and support conductors. The end windings may not be adequately supported within the core slots during operation of the generator and are often subject to severe vibrations and stresses which may cause adverse structural deformations. Structural deformation may also arise from electromagnetic forces which occur during abnormal short-circuit or fault conditions.
Several techniques have been developed in an attempt to prevent the end windings from undergoing negative structural deformations, such as that disclosed in U.S. Pat. No. 4,563,607 to Cooper et al. for a radial clamp assembly for dynamoelectric machine stator coil end turns. Top and bottom coils disposed within slots stator iron core are supported with a radial clamp, braces, brackets, rings, and strain blocks. The radial clamp Is typically positioned in the mid-involute region between the axial extreme of the end winding and the core.
The support blocks are located radially above and below a respective pair of end turns so that one support block bears against two parallel bottom coils and the other support block bears against two parallel top coils.
Upper and lower pins are disposed across the support block transverse to the orientation direction of the coils. A tensioned banding loop disposed continuously around the pins on each side of the coils so that the banding loop bears against the pins which, in turn, bear against their adjacent support blocks and coils.
With the banding loop in position, the pins are rotated to twist the banding loop for taking in excess slack, thereby, tightening the banding loop between the coils. Resin dispersed within the banding loop is then cured on site, typically by hot air flowing over the banding loop. The curing process requires additional time and expense to install. Typically, band curing extends work schedules, and consequently adds to the overall cost of the turbine generator. It would, therefore, be desirable to provide a more economical means of installing and maintaining a turbine generator. In addition, it would be desirable to reduce the number of components that must be accounted for during the installation of the radial clamps.
SUMMARY OF THE INVENTION
In view of the foregoing background, it is therefore an object of te present invention to provide an apparatus and related method for clamping coil windings using precured radial bands or the like. It is further an object of the present invention to reduce the components and processing steps typically used in clamping the stator coils of typical dynamo electric machines.
These and other objects, advantages and features of the present invention are provided by a clamping apparatus comprising a retaining platform for extending across a pair of coil windings positioned in a spaced relation, wherein the retaining platform has a bore extending therethrough. A connecting insert member is slidably carried within the bore of the retaining platform. The connecting insert member has a through-hole and means for admitting a rod into the through-hole. An elongated rod passes through the through-hole of the connecting insert member and includes a bulbous shaped end dimensioned for passing through the bore of the retaining platform while the through-hole of the connecting insert member prevents passage of the bulbous shaped end. therethrough. Thus, tension in the elongated rod biases the platform against the coil windings.
In one preferred embodiment, the connecting insert member comprises separable mating segments as the means for admitting a rod into the through-hole, and the through-hole of the connecting insert member includes a first dimension that permits passage of the bulbous end therein and a second dimension which prevents passage of the bulbous end therethrough. Further, one embodiment of the connecting insert member has a tapered cross-section for slidably securing within the bore of the retaining platform.
In a preferred embodiment, the elongated rod is formed from a precured and pretensioned banding material. A method aspect of the present invention includes forming the elongated rod by wrapping a band a multiplicity of times for forming a continuous loop, positioning first and second balls in a spaced relation within the loop, twisting the loop about an axis extending between the balls, and continuing the twisting until the balls are fully engulfed within the band to form a bulbous shape at each end. Further, a fiberglass tape impregnated and bonded with a resin is provided. Once the elongated rod is formed from the fiberglass tape, the twisted loop containing the balls is tensioned and the resin cured for forming a precured rigid elongated rod.
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Christodoulou Alex
Rowe Charles M.
Weltzien Thorsten
Dinh Le Dang
Ramirez Nestor
Siemens Westinghouse Power Corporation
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