Refurbishment of fatigue-cracked generator rotor forgings
In a paper presented at the 1994 IJPGC in Phoenix, AZ, TVA discussed the management of a fleet of fourteen generator rotors which had developed cracks in the axial cooling holes under the retaining rings and in the radial cooling holes in the rotor body. The management consisted of establishing the root cause of the crack initiation and propagation, initially establishing the flaw size distribution by eddy-current testing (ECT), performing reinspection at appropriate intervals, preheating the rotor prior to startup, lowering overspeed trip settings to 105%, confirming overspeed trip response by simulation rather than actual overspeed, and maintaining a spare generator rotor. Since the 1994 paper, one of the rotors developed an electrical liability, forcing its removal from service. While a replacement rotor which was on hand resolved the immediate crisis, the long term options were: (1) operate without a spare, (b) procure a new rotor with substantially improved mechanical properties and slightly improved electrical performance, or (c) refurbish the existing forging. After an exhaustive economic analysis, option C was identified as the most cost effective solution. This paper addresses the 43-inch rotor rehabilitation and rewind that has been successfully executed for less than half the cost of a new replacement rotor, without loss in operating flexibility.
- OSTI ID:
- 549974
- Report Number(s):
- CONF-961006-; ISBN 0-7918-1796-2; TRN: IM9753%%49
- Resource Relation:
- Conference: 1996 international joint power generation conference, Houston, TX (United States), 13-17 Oct 1996; Other Information: PBD: 1996; Related Information: Is Part Of 1996 international joint power generation conference: Proceedings. Volume 2; PWR-Volume 30; Kielasa, L. [ed.] [Detroit Edison Co., MI (United States)]; Weed, G.E. [ed.] [Eastman Kodak Co., Rochester, NY (United States)]; PB: 936 p.
- Country of Publication:
- United States
- Language:
- English
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