Minnesota Power applies concepts in EPRI manual to solve generator problem

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Hydro Review; (United States)

OSTI ID:6203633

Minnesota Power engineers returned a 35 year-old hydrogenerator to service at the utility's Thomsom Hydroelectric Station at minimum cost by consulting an Electric Power Research Institute manual, Synchronous Machine Operation With Cut-Out Coils. In the process, the utility realized a net benefit of more than $1 million by avoiding two more traditional approaches. The Thomsom Hydroelectric Station is part of the St. Louis River Hydroelectric Project. Following a routine maintenance outage of the 10-MW hydrogenerator to repair a bearing in 1991, Minnesota Power engineers found that oil from the bearing had spilled onto the stator coils, softening and weakening the insulation. Subsequent testing revealed several failed coils. The utility faces two options to return the generator to service: cut out the damaged coils or repair them. Facing a possible stator winding replacement costing $650,000 if simply cutting out the coils did not work, the EPRI guide enabled Minnesota Power to pursue a third solution, repairing the failed coils at a cost of $23,000. The utility chose this option even though the work-replacing two damaged coils and ten surrounding coils with epoxy mica coils-involved a longer outage than cutting out the failed coils would require. Minnesota Power saved $400,000 in replacement power by avoiding the three months of downtime that would be required to replace the entire winding. The utility also saved $650,000 it would have spent to replace the generator winding had it been destroyed. All in all, the utility realized a net benefit of more than $1 million.

• OSTI ID: 6203633
• Journal Information: Hydro Review; (United States), Journal Name: Hydro Review; (United States) Vol. 7:4; ISSN HYREE8; ISSN 0884-0385
• Country of Publication: United States
• Language: English

Related Subjects

13 HYDRO ENERGY
130700* -- Hydro Energy-- Power-Conversion Systems
COST BENEFIT ANALYSIS
DOCUMENT TYPES
ECONOMIC ANALYSIS
ECONOMICS
ELECTRIC COILS
ELECTRIC GENERATORS
ELECTRICAL EQUIPMENT
EPRI
EQUIPMENT
MAINTENANCE
MANUALS
REPAIR
WATER CURRENT POWER GENERATORS