Electroplating method for sealing liquid-cooled generator stator bar structures

Abstract

The interior of a stator bar clip that is joined to the end of a stator bar is electroplated so that a metallic barrier coating overlies the braze joint between the stator bar and the clip to define a seal at and around the joint that is substantially impermeable to liquid.

Description

BACKGROUND OF THE INVENTION [0001] Water-cooled stator bars for electrical generators are comprised of a plurality of small rectangular solid and hollow copper strands brazed to one another to form a bar. The ends of the strands are brazed to an end fitting, typically referred to as stator bar clip. A cover is brazed to the clip window. The end fitting serves as both an electrical and a cooling flow connection for the stator bar. [0002] The hollow end fitting typically includes an enclosed chamber for ingress or egress of stator bar cooling liquid, typically deionized water. At one end, the end fitting receives the ends of the strands of the stator bar. The fitting and the peripherally outermost copper strands of the stator bar are brazed to one another. The opposite end of the fitting is connected to a stator cooling conduit. [0003] Liquid cooled stator bar clips have gone through design changes over the years. However, they typically contain mixed solid and hollow strands brazed t...

AI Technical Summary

Benefits of technology

[0008] The invention proposes an electroplating method to deposit a thin layer of metallic barrier coating on a part of or the entire interior surface of a liquid-cooled stator bar clip. The metallic layer provides a corro

Problems solved by technology

Over time, leaks can develop about the connection between the stator bar ends and the stator bar fitting, between cover and clip as well as between adjacent strands.

This coolant contact with the braze joint and cooper strands is believed to cause corrosion and consequent leakage.

Thus, the process is labor intensive and requires 100% inspection.

As a result, the process can be labor intensive, takes a long time to complete, and can produce defects.

There are also other leak issues in liquid cooled generators.

Indeed, there are many types of leaks associated with water-cooled generators.

But other leaks are caused by porosity, cracking and localized damage during manufacturing rather than as a result of corrosion.

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