Method of Servicing a Power Generator
A method of servicing a stator frame of a power generator. The method includes removing a first stator core from a main housing of the stator frame, removing a plurality of first dove-tail shaped keybars that extend axially within and are coupled to a main support structure forming part of the main housing, and installing a plurality of second keybars in the main support structure. The second keybars are adapted to support a second stator core. Each of the second keybars has a generally rounded engagement surface and the second stator core includes recesses with shapes corresponding to the generally rounded engagement surfaces of the second keybars such that the second stator core can be securely supported in the main support structure by the second keybars.
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This application claims the benefit of U.S. Provisional Application Ser. No. 61/037,887, entitled CORE TO FRAME ATTACHMENT IN A UNIT WITHOUT BUILDING BOLTS, filed Mar. 19, 2008, the entire disclosure of which is incorporated by reference herein.
FIELD OF THE INVENTIONThe present invention relates to power generators, and more particularly, to a method of servicing stator frames in power generators.
BACKGROUND OF THE INVENTIONU.S. Pat. No. 5,875,540, the entire disclosure of which is incorporated by reference herein, discloses a process for forming a stator core in a stator frame. The process involves forming a plurality of core modules or donuts, each of which comprises a plurality of stator core rings laminated together. The stator frame is placed in an upright position. A predefined number of the core modules are then lowered into the upright stator frame. For a power generator which has been in operation for some time and is in need of a new stator core, turning its stator frame upright to receive a new stator core can be very difficult.
U.S. Pat. Nos. 7,302,754; 7,353,586; and 7,395,594, the entire disclosures of which are incorporated by reference herein, are directed at installing stator cores into stator frames without placing the stator frame in an upright position. U.S. Pat. No. 7,202,587, the entire disclosure of which is also incorporated by reference herein, discloses mounting stator core donuts having enlarged grooves in a stator frame using wedges that disperse forces to the donuts in a circumferential manner. The enlarged grooves make installing the donuts less difficult, while the wedges ensure a tight fit of the laminations within the stator frame.
In accordance with a first aspect of the present invention, a method of servicing a stator frame of a power generator is provided. The method comprises removing a first stator core from a main housing of the stator frame, removing a plurality of first dove-tail shaped keybars that extend axially within and are coupled to a main support structure forming part of the main housing, and installing a plurality of second keybars in the main support structure. The second keybars are adapted to support a second stator core. Each of the second keybars has a generally rounded engagement surface and the second stator core includes recesses with shapes corresponding to the generally rounded engagement surfaces of the second keybars such that the second stator core can be securely supported by the main support structure via the second keybars.
The main support structure may comprise a plurality of stator bore rings and a plurality of frame beams, wherein the second keybars are coupled to the frame beams.
Installing a plurality of second keybars in the main support structure may comprise bolting the second keybars to the frame beams.
Bolting the second keybars to the frame beams may comprise installing bolts into counter-bored holes until end portions of the bolts are inserted past a radially inner surface of the second keybars.
The method may further comprise installing the second stator core onto the second keybars.
The method may further comprise servicing the frame beams such that the second stator core can be more easily axially slid onto the second keybars without the second stator core contacting the frame beams.
Servicing the frame beams may comprise removing radially inner corner edges of the frame beams to create a radial clearance for a radial outer edge of the second stator core.
A portable milling machine may be utilized to remove the radially inner corner edges of the frame beams.
In accordance with a second aspect of the present invention, a kit for servicing a stator frame of a power generator is provided, wherein the stator frame includes dove-tail keybars installed therein supporting a first stator core within a main support structure of a main housing. The kit comprises a plurality of second keybars and fasteners to couple the second keybars to the main support structure of the main housing. Each of the second keybars has a generally rounded engagement surface and is adapted to replace the dove-tail shaped keybars installed in the main support structure. The second keybars are adapted to support a second stator core in the main support structure. The second stator core includes recesses with shapes corresponding to the generally rounded engagement surfaces of the second keybars.
The main support structure may comprise a plurality of stator bore rings and a plurality of frame beams, wherein the second keybars are coupled to the frame beams with the fasteners.
The fasteners may comprise bolts, which may be installed through counter-bored holes in the second keybars.
End portions of the second keybars may extend further radially inwardly than a radial end of the bolts.
The kit may further comprise a portable milling machine for removing radially inner corner edges of the frame beams to create a radial clearance for a radial outer edge of the second stator core.
While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed that the present invention will be better understood from the following description in conjunction with the accompanying Drawing Figures, in which like reference numerals identify like elements, and wherein:
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, specific preferred embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention.
After periods of electrical power generator use, it may become necessary to replace a stator core within a stator core frame of the power generator. As mentioned above, U.S. Pat. Nos. 7,302,754; 7,353,586; and 7,395,594 are directed at installing stator cores into stator frames without placing the stator frame in an upright position. Typically, the systems, structures, and methods disclosed by these patents are utilized with keybars having rounded engagement surfaces, i.e., the keybars are generally rounded in shape. This is because replacement of a stator core onto rounded keybars using a horizontal replacement process is believed to be easier and more efficient as compared to replacement of a stator core onto dove-tail shaped keybars.
As shown in
In accordance with the present invention, after a stator core mounted to dove-tail shaped keybars 12 of a stator frame 10 is removed, the dove-tail shaped keybars 12 are then removed and replaced with generally rounded or cylindrical-shaped keybars followed by the installation of a new stator core onto the rounded keybars. By replacing the dove-tail shaped keybars 12 with rounded keybars, it is believed that installation of the new stator core within the stator core frame having rounded keybars will be accomplished in a more efficient manner.
Donuts 14 mounted on dove-tail shaped keybars 12, see
Once the stator core donuts 14 are removed from the stator frame 10, the dove-tail shaped keybars 12 are removed from the frame beams 16 by removing fasteners 22, such as bolts, extending through counter-bored holes 24 (see
In order for a replacement donut 30 (see
Replacement building bolts or keybars 32 are then installed on the frame beams 16′ in generally the same locations as the previously removed keybars 12. As shown in
The replacement keybars 32 include counter-bored holes 36 formed therein, as shown in
As shown in
In the illustrated embodiment, the grooves 50 are slightly oversized to allow for easier installation of the donuts 30 onto the replacement keybars 32. So as to create a tight fit between each donut 30 and the replacement keybars 32, first and second wedge structure assemblies 54 and 56 are provided in each groove 50 between the donut 30 and the corresponding keybar 32, see
As noted above, the replacement of a stator core onto rounded keybars using a horizontal replacement process is believed to be easier and more efficient as compared to replacement of a stator core onto dove-tail shaped keybars. Hence, replacing the dove-tail shaped keybars 12 with the replacement keybars 32 facilitates an easier replacement of a stator core within the stator frame 10. In particular, since tooling, methods, and structure have been developed to replace stator cores within stator frames using horizontal processes and cylindrical-shaped keybars, these developed tooling, methods, and structure can be utilized in the stator frames 10 once the replacement keybars 32 are installed. For example, the use of the replacement donuts 30 and the first and second wedge structure assemblies 54, 56 with the replacement cylindrical-shaped keybars 32 avoids developing new tooling, methods, and structure that would be required to use a horizontal process to replace a stator core in a stator frame that includes dove-tail shaped keybars.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Claims
1. A method of servicing a stator frame of a power generator comprising:
- removing a first stator core from a main housing of the stator frame;
- removing a plurality of first dove-tail shaped keybars that extend axially within and are coupled to a main support structure forming part of the main housing; and
- installing a plurality of second keybars in the main support structure adapted to support a second stator core, each of the second keybars having a generally rounded engagement surface, the second stator core having recesses with shapes corresponding to the generally rounded engagement surfaces of the second keybars such that the second stator core can be securely supported by the main support structure via the second keybars.
2. The method according to claim 1, wherein the main support structure comprises a plurality of stator bore rings and a plurality of frame beams, the second keybars being coupled to the frame beams.
3. The method according to claim 2, wherein said step of installing a plurality of second keybars in the main support structure comprises bolting the second keybars to the frame beams.
4. The method according to claim 3, wherein said step of bolting the second keybars to the frame beams comprises installing bolts into counter-bored holes formed in the second keybars.
5. The method according to claim 3, further comprising installing the second stator core onto the second keybars.
6. The method according to claim 5, wherein said step of installing the bolts into counter-bored holes formed in the second keybars comprises installing the bolts into the counter-bored holes until end portions of the bolts are inserted past a radially inner surface of the second keybars.
7. The method according to claim 2, further comprising servicing the frame beams such that the second stator core can be more easily axially slid onto the second keybars without the second stator core contacting the frame beams.
8. The method according to claim 7, wherein said step of servicing the frame beams comprises removing radially inner corner edges of the frame beams to create a radial clearance for a radial outer edge of the second stator core.
9. The method according to claim 8, wherein a portable milling machine is utilized to remove the radially inner corner edges of the frame beams.
10. A kit for servicing a stator frame of a power generator, the stator frame having dove-tail keybars installed therein supporting a first stator core within a main support structure of a main housing, said kit comprising:
- a plurality of second keybars each having a generally rounded engagement surface and adapted to replace the dove-tail shaped keybars installed in the main support structure, said second keybars being adapted to support a second stator core in the main support structure, the second stator core having recesses with shapes corresponding to the generally rounded engagement surfaces of the second keybars; and
- fasteners to couple said second keybars to the main support structure of the main housing.
11. The kit according to claim 10, wherein the main support structure comprises a plurality of stator bore rings and a plurality of frame beams, said second keybars being coupled to said frame beams with said fasteners.
12. The kit according to claim 11, wherein said fasteners comprise bolts.
13. The kit according to claim 12, wherein said bolts are installed through counter-bored holes in said second keybars.
14. The kit according to claim 13, wherein end portions of said second keybars extend further radially inwardly than a radial end of said bolts.
15. The kit according to claim 10, further comprising a portable milling machine for removing radially inner corner edges of said frame beams to create a radial clearance for a radial outer edge of said second stator core.
Type: Application
Filed: Jan 13, 2009
Publication Date: Sep 24, 2009
Applicant: SIEMENS ENERGY, INC. (Orlando, FL)
Inventors: Craig P. Notarange (Orlando, FL), David T. Allen (Longwood, FL)
Application Number: 12/352,732
International Classification: H02K 15/06 (20060101);