Powder coating for generator stator bar end fitting and method for applying the power coating

• US 20060102702A1
• Filed: 11/09/2004
• Published: 05/18/2006
• Est. Priority Date: 11/09/2004
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Wang, Yu, Lusted, Roderick Mark, Mall, Waheed Tony
• Granted Patent: US 7,150,091 B2
• Time in Patent Office: Days
• US Class Current: 228/248.100
• CPC Class Codes: H02K 15/0093 Manufacturing or repairing cooling fluid boxes, i.e. terminals of fluid cooled windings ensuring both electrical and fluid connection
• CPC Class Codes: H02K 15/12 Impregnating, heating or drying of windings, stators, rotors or machines
• CPC Class Codes: H02K 3/44 Protection against moisture or chemical attack; Windings specially adapted for operation in liquid or gas
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine

Abstract

A method of sealing a generator stator bar and a stator bar end fitting receiving the end including the steps of: brazing the fitting to the end of the stator bar with a braze material; applying a powder coating material to the end of the stator bar in the fitting; and curing the powder coating material to form a barrier coating on the end of the stator bar and the adjoining interior surfaces of the fitting.

Claims

1. A method of sealing the junction of a generator stator bar end and a stator bar end fitting receiving the bar, comprising:

attaching the fitting to the end of the stator bar with a braze material;

applying a powder coating material at least to the end of the stator bar attached to the fitting, through a chamber in the fitting; and

curing the powder coating material to form a barrier coating on the end of the stator bar and the adjoining interior surfaces of the fitting.

2. The method as in claim 1, wherein said curing includes heating the fitting.

3. The method as in claim 1, wherein attaching the fitting comprises brazing the fitting and stator bar with a phosphorous copper braze alloy and the powder coating material comprises a thermosetting epoxy.

4. The method as in claim 1, wherein said applying comprises electrostatically charging the powder coating material and spraying said powder coating material into said chamber.

5. The method as in claim 1, wherein the fitting comprises a stator bar clip.

6. A method of sealing a stator bar end to a stator bar clip, the clip having a chamber for receiving a liquid through an opening and in communication with hollow strands in said stator bar to enable coolant liquid flow through the hollow strands, said method comprising:

brazing the clip to the end of the stator bar;

electrostatically charging a powder coating material and spraying said powder coating material into said chamber; and

curing the powder coating material to form a barrier over the end of the stator bar in the fitting.

7. The method as in claim 6, wherein said curing includes heating the fitting.

8. The method as in claim 6, wherein said stator bar further comprises solid strands and said hollow strands extend into said chamber a distance greater than said solid strands.

9. The method of claim 6, wherein brazing the clip comprises brazing the clip and stator bar with a phosphorous copper braze alloy and the coating material comprises a thermosetting epoxy.

10. An assembly comprising a stator bar end and a fitting receiving the end to define a seal substantially impermeable to liquid, the fitting having a chamber for receiving a liquid through an opening in the fitting and in communication with hollow strands forming at least a portion of said stator bar and for flow of the liquid through the hollow strands, wherein at least a portion of an interior surface of said chamber has a polymer layer powder coated and cured on a surface thereof.

11. An assembly as in claim 10, wherein said polymer layer extends substantially continuously over a junction of said fitting and said stator bar end.

12. An assembly as in claim 10, wherein said polymer comprises a thermosetting epoxy.

13. An assembly as in claim 10, wherein the polymer layer has a thickness of about 0.002 to about 0.050 inches.

14. An assembly as in claim 13, wherein the polymer layer has a thickness of about 0.018 to about 0.020 inches.

15. A fitting for a stator bar of a generator comprising:

a fitting housing having a collar at a first end and a cooling fluid coupling at an opposite end, wherein said collar is configured to be brazed to an end of the stator bar;

a chamber extending from the first end to the opposite end of the fitting; and

a polymer coating on an end of the stator bar in said chamber and forming a seal between the end and a remaining portion of the chamber.

16. A fitting as in claim 15, wherein said polymer layer extends substantially continuously over a junction of said fitting and said stator bar end.

17. A fitting as in claim 15, wherein said polymer comprises a thermosetting epoxy.

18. A fitting as in claim 15, wherein the polymer layer has a thickness of about 0.002 to about 0.050 inches.

19. A fitting as in claim 18, wherein the polymer layer has a thickness of about 0.018 to about 0.020 inches.

20. A method of coating the interior of a stator bar clip including the steps of electrically grounding the stator bar clip, spraying an electrostatically charged powder into the stator bar clip to form a layer of the powder thereon to a predetermined thickness and curing the powder spray-coated on the stator bar clip to form a substantially continuous corrosion barrier layer on an exposed interior surface thereof.