1. Field of the Invention
The invention relates to generator stator core removal, and more particularly to field removal and reinstallation of assembled stator cores from non-vertically oriented generator frames, including horizontally-oriented generator frames.
2. Description of the Prior Art
During a generator major overhaul stator cores are removed from the generator frame. Old core windings and insulation are stripped from the stator core lamina stack and replaced with new ones. The replacement stator core is assembled within the generator frame. Generally the overhaul is performed at the power generation site, rather than transporting the entire generator to an offsite repair facility.
Some generator designs facilitate removal of their entire stator core assembly as a module by orienting the core axis in a vertical position and lifting the core module with a crane or other hoisting device that is coupled to a lifting plate affixed to an axial end of the stator core. When vertically lifting an entire stator core module care must be taken to avoid damaging either the core or the generator frame by inadvertent contact during lifting. Given the relatively large diameter, axial length and weight of a stator core, and the relatively small radial clearance with the generator frame a small yaw of the stator core during the hoisting operation may cause inadvertent impacts. Cranes, hoists and similar heavy moving equipment are expensive to purchase or lease, require logistic planning to have them available on a job site and skilled operating engineers, thus often necessitating retention of specialized subcontractors to complete the generator refurbishment. It is desirable to minimize the number of subcontractors needed to refurbish a generator, as well as minimize likelihood of generator damage that might result from impacts incurred during vertical stator core hoisting.
Other generator designs are not suitable for vertically lifting stator cores prior to their refurbishment. In those generator designs the stator core is disassembled in place by hand. Service personnel serially and repetitively remove layers of core windings, insulation and individual core lamina (often up to 75000 individual laminations) in the lamina stack with hand-held tools while the generator frame is oriented with its rotor rotational axis in a vertical or horizontal position (analogous to an archaeological excavation). Such hand labor is time consuming and expensive. A typical in-place rotor core disassembly within the generator frame requires 3-8 days' work by a service crew to remove layers of lamina, windings and insulation. Core disassembly external to the generator consumes less service time, and allows quicker generator service resumption.
Accordingly, an object of the invention is to remove a stator core from a generator as a module without vertically hoisting the core, so as to eliminate the need for cranes or other heavy hoisting equipment.
Another object of the invention is to remove a stator core from a generator as a module without vertically hoisting the core, so as to minimize likelihood of generator damage arising from inadvertent contact of the stator core and generator frame.
An additional object of the invention is to minimize hand labor required to remove a stator core from a generator, and specifically to avoid full core disassembly in place with hand labor.
These and other objects are achieved in accordance with the present invention by a method for separating an intercoupled stator core from a non-vertically oriented generator frame. The method features decoupling respective coupled stator core and frame coupling members. After the decoupling at least one sliding member is interposed between the stator core and frame. Thereafter the respective stator core and frame are slidably separated relative to each other on the at least one sliding member, so that they are separated from their initially coupled relative positions. The method of this invention avoids the need to hoist the stator core vertically out of the generator frame, or the need to disassemble the core in its entirety by hand.
The present invention also features an apparatus for separating a stator core having a first coupling member relative to a non-vertically oriented generator frame having a second coupling member in engagement with the first coupling member. The apparatus comprises a slidable member adapted for interposition between the disengaged stator core and generator frame. The slidable member enables relative sliding motion between the stator core and generator frame. In some embodiments the slidable member comprises a rail having a first surface for slidable engagement with one of the coupling members. In other embodiments the rail further comprises a second slidable surface for slidable engagement with the other of the coupling members. In yet other embodiments the slidable member comprises a roller adapted for rolling contact with one of the opposed stator core or generator structures and an engagement surface adapted for contact with the other structure. Interposition of a slidable member between the stator core and frame while the generator is oriented in a non-vertical position avoids inadvertent impact of the stator core and generator frame during their separation.
Other embodiments of the present invention feature a system for separating a stator core having axial ends and a first coupling member relative to a non-vertically oriented generator frame having axial ends and a second coupling member in engagement with the first coupling member. The system includes first and second raising end plates adapted for coupling to respective axial ends of a stator core. The end plates are adapted for projecting axially outwardly from respective axial ends of the generator frame, for coupling to a raise mechanism and thereafter separating the first and second coupling members when the raise mechanism raises stator core. The system also includes a slidable member adapted for interposition between the stator core and generator frame. The slidable member enables relative sliding motion between the stator core and generator frame. The invention system avoids the need to utilize cranes or other hoisting heavy equipment and avoids inadvertent impact of the stator core and generator frame during their separation.
The objects and features of the present invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art.
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
After considering the following description, those skilled in the art will clearly realize that the teachings of the present invention can be readily utilized in separation of stator cores from generator frames by orienting them in a non-vertical position, separating them radially, such as with a lifting jack or other lifting device, and interposing at least slidable member between them. Thereafter the stator core is separated axially relative to the generator frame by sliding it on the slidable member(s). In this manner cranes or other hoisting heavy equipment is not needed to separate the stator core from the generator frame, and likelihood of inadvertent damage caused by stator core/generator frame contact is avoided. By removing the stator core as a module extensive hand labor is avoided as compared to that needed to remove portions of the core while still in the generator frame.
Referring to
In the embodiment of
An alternate exemplary embodiment of a stator core separation system is shown in
The roller assembly 90 preferably comprises a height adjustment mechanism 96, such as a fluid jack, screw jack, or adjustable shim stack, which facilitates selective relative radial adjustment between the generator frame 30 and stator core 40. Advantageously if the height adjustment mechanism 96 is a lift mechanism or jack, it can be utilized to raise the stator core 40 away from the generator frame 30 without the need for end raising plates 72/raising plate extensions 74, frame end plates 76 or external raising mechanisms 78 that were described in connection with the previous embodiment of
Either stator core separation system embodiment may also be utilized to install a stator core 40 into a generator frame 30. In this manner, a stator core 40 can be removed or installed in a generator 20 as a modular structure, without a need to perform core assembly or disassembly by hand within the confined space of the generator frame 30.
Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.