Patent ID: 12255513

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views,FIG.1is a schematic diagram of an exemplary embodiment of a combined cycle power generation system10. The combined cycle power generation system10may include a gas turbine, a steam turbine, and a heat recovery steam generator (HRSG). Specifically, the combined cycle system10may include a gas turbine12for driving a first generator14to produce electrical power. The gas turbine12may include a turbine16, a combustor18, and a compressor20. The combined cycle system10also may include a steam turbine22for driving a second generator24. The steam turbine22may include a low-pressure section26(LP ST), an intermediate-pressure section28(IP ST), and a high-pressure section30(HP ST). Although the gas turbine12and the steam turbine22may drive separate generators14and24as is shown herein, the gas turbine12and the steam turbine22also may be utilized in tandem to drive a single load via a single shaft. The generators and components described herein and the like may be incorporated into other types of power generation systems.

The combined cycle system10also may include a multi-stage heat recovery steam generator32. Heated exhaust gas34from the gas turbine12may be directed into the heat recovery steam generator32to heat the steam used to power the steam turbine22. Exhaust from the low-pressure section26of the steam turbine22may be directed into a condenser36. Condensate from the condenser36may, in turn, be directed into a low-pressure section of the heat recovery steam generator32with the aid of a condensate pump38.

FIG.2is a sectional view of an example of a generator40that may serve as the generator14and/or the generator24in the combined cycle power generation system10ofFIG.1or in various other types of power generation systems. The generator40may include an annular frame42, a stator46, and a rotor48. The rotor48may be driven to rotate by a gas turbine, a steam turbine, a wind turbine, a hydro turbine, an internal combustion engine, or any other suitable device configured to provide a rotational output. The rotor48may include a wire winding about a magnetic core. The rotor48may be disposed within the stator46, which is configured to provide a stationary magnetic field. Rotation of the rotor48within the stator46generates electrical current within the wire winding, thereby producing an electrical output from the generator40.

FIG.3is a plan view of an embodiment of the generator rotor48of the generator40ofFIG.2. As is shown, the rotor48may include a coupling54, such as a mechanical mode or power turbine coupling, on one end. The rotor48extends in an axial direction50and rotates in a circumferential direction52. Further, the rotor48extends within the stator46in a radial direction53. On the other end of the rotor48, there may be collector rings56thereon to provide an electrical junction for the rotor field windings. A collector fan58may be located adjacent to the collector rings56. The rotor48may have a large diameter body60that holds coil windings62. The coil windings62may be disposed in axially oriented 50 slots that extend radially53outward from the middle of the rotor48to the axial ends of the rotor body60.

FIG.4shows a side view of a pair of the collector rings56positioned on the rotor48and a collector terminal64. The collector terminal64may be in the form of an elongated stud66that extends through a cut-out68in a collector ring flange70of the collector ring56and into a bore72in the rotor48. The stud66may have a hex-shaped head67and the like thereon. As described above, the collector rings56may be positioned adjacent to a brush holder74with a number carbon brushes76. Due to wear, carbon dust from the brushes76may accumulate about the cut-out68and the bore72of the collector terminal64. The visible collector terminal64one the left connects a left collector ring to an axial bore copper78at the bottom of the view. A right collector ring has the same configuration, just about rotated 180° and is in communication with an opposite axial bore copper80. Thus, current flows through the brush rigging into one collector ring, through the respective terminal and bore copper into the rest of the winding, into the opposite bore copper, through the other collector terminal, and out through the other collector ring and brush rigging.

FIG.5shows a collector terminal dust mitigation bushing assembly100as may be described herein. The collector terminal dust mitigation bushing assembly100may be a two piece combination. The collector terminal dust mitigation bushing assembly100includes an outer element105such as an outer bushing110and an inner element115such as an inner bushing120. The outer bushing110may have an outer substantially “D”-like shape130with an inner circular aperture140. The outer bushing110may be sized to fit within the cut-out68in the collector ring flange70of collector rings56used with air cooled generator rotors48and the like having static excitation systems.

The inner bushing120may have a circular outer shape150and a pointed inner shape160defining an inner bushing aperture165therein. The circular outer shape150of the inner bushing120fits within the circular aperture140of the outer bushing110. The pointed inner shape160of the inner bushing120accepts the collector terminal stud66of the collector terminal64at any orientation. In this example, the pointed inner shape160includes eighteen points170but any number of raised points170may be used. For example, six to eighteen or more raised points170may be used herein. The inner element115may be any type of interposing element or material that may accommodate the collector terminal stud66. For example, different types of sealants, fillers, shims, and the like may be used.

FIGS.6-9show variations in the inner bushing120. The relative positions of the rotor48, the collector ring56, and the collector terminal64may vary from unit to unit across the fleet. The collector terminal dust mitigation bushing100thus may have an inner bushing kit180with a number of differently configured inner bushings120that may be configured to accommodate the outer bushing110. For example,FIG.6shows the inner bushing120with the aperture165of the pointed inner shape160having a dead center positon190.FIG.7shows the inner bushing120with the aperture165of the pointed inner shape160having a first (axial) offset position200.FIG.8shows the inner bushing120with the aperture165of the pointed inner shape160having a second (axial) offset position210.FIG.9shows the inner bushing120with the aperture165of the pointed inner shape160having a third (axial) offset position220. Each offset may move the aperture165of the pointed inner shape160about 20 mils or so off of the dead center position190. Other distances and other directions may be used herein. In addition to axial offsets, different types of radial offsets also may be used. For example, one side of the inner bushing120may be thicker or deeper than the other side. Any number of variations and combinations may be used herein depending upon the nature of the fleet and the component therein. Other components and other configurations may be used herein.

Once the correct inner bushing120has been selected, the inner bushing120may be bonded to the outer bushing110via conventional adhesives or other types of connection means. The collector terminal dust mitigation bushing assembly100then may be attached to the collector terminal64.FIGS.10and11show the collector terminal dust mitigation bushing assembly100as installed about a collector terminal64. A taper230may be machined into the outer bushing110for a smooth transition to the cut-out68of the collector ring56so as to accommodate a distribution strap240thereon. The taper230may be machined on site with minimal tooling for a custom fitting. Once in place, the combined collector terminal dust mitigation bushing assembly100eliminates surface discontinuity on the collector ring56so as to reduce cooling air turbulation.

In use, the correct inner bushing120may be selected to accommodate the position of the collector terminal64with respect to the collector ring56and the cut-out68. The inner bushing120fits into the outer bushing120and around the collector terminal stud66. The pointed inner shape of the inner bushing120will accept the collector terminal stud66at any orientation. Given that the inner bushings120are provided in the kit180, the installer can choose which inner bushing120to use based on the specific parts and configurations at hand. Any required tooling is minimal such that the overall installation does not require the parts to be sent out for machining. Therefore, the fit can be performed in a shop or onsite in a timely manner and with minimal external support.

The inner bushing120may be sealed to the standard outer bushing110. The combined collector terminal dust mitigation bushing assembly100then may be applied to the collector terminal64. The combined collector terminal dust mitigation bushing assembly100thus may flexibly accommodate offsets and misalignments between the respective components. The combined collector terminal dust mitigation bushing assembly100does not require that the components will always be in the same position relative to each other. Rather, the two-piece design accommodates any relative positioning.

The combined collector terminal dust mitigation bushing assembly100thus provides full blockage of the collector terminal bore72to prevent the entry of dust or other contaminates. Functionally, the outer bushing110blocks dust entry axially and radially. The inner bushing120completes the radial dust blockage and secures the outer bushing110in place.

The combined collector terminal dust mitigation bushing assembly100may be provided as an add-on to field rewinds, as a standalone offering during normal onsite maintenance, or as a mitigation to a forced outage. The combined collector terminal dust mitigation bushing assembly100prevents the entry of all dust and other contaminates as opposed to minimizing accumulation for an extended generator lifetime with reduced maintenance.

It should be apparent that the foregoing relates only to certain embodiments of this application and resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.

Further aspects of the invention are provided by the subject matter of the following clauses:1. A collector terminal dust mitigation assembly for use with collector terminals of generators to prevent dust entry into a collector terminal bore in a collector ring, wherein the collector terminals comprise varying positions with respect to the collector rings, the collector terminal dust mitigation assembly comprising: one of plurality of inner elements configured for a specific position of a collector terminal with respect to a collector ring; and a standard outer element sized to accommodate the inner element.2. The collector terminal dust mitigation assembly of any preceding clause wherein the inner element comprises an inner bushing.3. The collector terminal dust mitigation assembly of any preceding clause, wherein the inner bushing comprises a circular outer shape.4. The collector terminal dust mitigation assembly of any preceding clause, wherein the inner bushing comprises a pointed inner shape defining an aperture therein.5. The collector terminal dust mitigation assembly of any preceding clause, wherein the pointed inner shape comprises a plurality of raised points.6. The collector terminal dust mitigation assembly of any preceding clause, wherein the aperture comprises a center position in the inner bushing.7. The collector terminal dust mitigation assembly of any preceding clause, wherein the aperture comprises an offset position in the inner bushing.8. The collector terminal dust mitigation assembly any preceding clause, further comprising a kit of a plurality of inner bushings.9. The collector terminal dust mitigation assembly of any preceding clause, wherein the standard outer element comprises an outer bushing.10. The collector terminal dust mitigation assembly of any preceding clause, wherein the outer bushing comprises a substantial “D” like shape.11. The collector terminal dust mitigation assembly of any preceding clause, wherein the substantial “D”-like shape comprises a circular aperture.12. The collector terminal dust mitigation assembly of any preceding clause, wherein the circular aperture is sized to accommodate the inner bushing therein.13. The collector terminal dust mitigation assembly of any preceding clause, wherein the outer bushing comprises a taper thereon.14. The collector terminal dust mitigation assembly of any preceding clause, wherein the collector terminal comprises a stud with a head and wherein the inner element accommodates the head therein.15. A method of preventing entry of dust into a collector terminal positioned about a collector ring of a generator, comprising: selecting an inner bushing configured to accommodate a relative position of the collector terminal with respect to the collector ring; attaching the selected inner bushing to a standard outer bushing; applying a taper to the outer bushing; and installing the combined inner bushing and outer bushing onto the collector terminal.16. A collector terminal dust mitigation bushing assembly for use with collector terminals of generators to prevent the entry of dust into a collector terminal bore in a collector ring, wherein the collector terminals comprise varying positions with respect to the collector rings, the collector terminal dust mitigation bushing assembly comprising: a plurality of inner bushings; wherein one of the plurality of inner bushings comprises an aperture configured for a specific position of a collector terminal with respect to a collector ring; and a standard outer bushing sized to accommodate the inner bushing and to be sealed thereto.17. The collector terminal dust mitigation bushing assembly any preceding clause, wherein the inner bushing comprises a circular outer shape and an aperture therein.18. The collector terminal dust mitigation bushing assembly of any preceding clause, wherein the aperture comprises a center position in the inner bushing.19. The collector terminal dust mitigation bushing assembly of any preceding clause, wherein the aperture comprises an offset position in the inner bushing.20. The collector terminal dust mitigation bushing assembly of any preceding clause, wherein the outer bushing comprises a substantial “D” like shape defining a circular aperture sized for the inner bushing.