The invention relates to dry type transformers and, more particularly, to a radial drop winding for open wound medium voltage dry type transformers.
Dry type transformer windings incorporate a conductor, typically of aluminum or copper, and solid insulation to prevent dielectric failure. There are multiple conventional methods to control the geometry of these transformers to keep labor and material cost as low as possible. One of the metrics to determine material content is the fill factor or the amount of space inside a coil used for the conductor.
Radial drop winding techniques are typically used with coils that are vacuum cast using removable metal molds to hold the windings in place until the epoxy is rigid enough to support the mechanical forces.
Thus, there is a need to provide a radial drop winding for open wound/ventilated coils without relying on the vacuum cast or resin encapsulated process so as to reduce labor cost.
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is obtained by a method that provides a medium voltage radial drop winding for an open wound transformer. The method provides a plurality of non-electrically conductive posts arranged to define an interior space. Each post is of generally L-shape having a main body and a leg extending from a bottom end of the main body. During an open winding process, conductive wire is dropped to build up lengthwise along the posts to define at least one generally cylindrical winding segment supported by the legs of the posts.
In accordance with another aspect of the disclosed embodiment, a radial drop winding for an open wound transformer includes support structure having a plurality of non-electrically conductive posts. Each post is of generally L-shape having a main body and a leg extending from a bottom end of the main body. The posts are arranged so as to define an interior space. At least one generally cylindrical winding segment including conductive wire is disposed about the posts and supported by the legs.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:
With reference to
With reference to
The post 10 and spacer structure 20 are of non-electrically conductive material such as polyester glass. With reference to
With reference to
In the embodiment shown in
The posts 10 and spacer structure 20 ensure that the winding segment(s) hold a predictable shape and survive the manufacturing, shipping, installation, and energization processes.
This drop winding concept can be applied to medium voltage dry type transformers that use a dipped or sprayed varnish coating process for environmental protection and enhanced mechanical performance. It can be used with aluminum or copper windings, paper/film wrapped conductors or film coated conductors at voltages presently up to 36 kV and 2 MVA, although even higher distribution voltages and higher distribution MVAs are contemplated.
The medium voltage radial drop winding 62 for open wound/ventilated coils will reduce direct labor and increases the effective fill factor, while maintaining a nearly linear voltage distribution inside the winding. The open wound or open ventilated coils do not use solid epoxy to fill the space between the coils or turns in the same winding. The radial drop winding 62 solves the issue of how to apply radial drop windings on open wound transformers without relying the vacuum cast or resin encapsulated process.
Other advantages of the medium voltage radial drop winding 62 includes the reduction of material content, does not require vacuum cast or resin encapsulated processes, reduces manufacturing time, enhances mechanical performance versus a typical open wound disk configuration, and reduces overall footprint and weight.
The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
This application is a continuation-in-part of U.S. application Ser. No. 13/914,669, filed on Jun. 11, 2013, the content of which is hereby incorporated by reference into this specification.
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Entry |
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International Search Report and Written Opinion in PCT/US2014/067852 dated Mar. 13, 2015. |
Number | Date | Country | |
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20140361862 A1 | Dec 2014 | US |
Number | Date | Country | |
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Parent | 13914669 | Jun 2013 | US |
Child | 14101440 | US |