Resolving problems of high vibration in hydroelectric machinery
- Powertech Labs, Inc., Surrey, British Columbia (Canada)
High vibrations in hydroelectric machinery often will necessitate derating of a unit's capacity so that it remains in acceptable operating condition. Such was the case at B.C. Hydro's 700-MW Peace Canyon Generating Station. At this station, a 175-MW turbine-generator experienced high stator split-phase currents on cold starts and high turbine bearing vibration at high loads. The vibration, measured at 24 mils (0.024 inch) peak to peak, exceeded the as-set turbine bearing clearance of 14 mils (0.014-inch) diametrical. Consequently, the utility derated the machine by 25 MW for a period of approximately seven months. B.C. Hydro contacted Powertech Labs Inc., the utility's applied technology subsidiary, and assigned the task of resolving the problem and restoring the unit to design capacity. Using vibration amplitude and phase vibrations as functions of the unit's rotational speed and load, Powertech investigators concluded that the problem of high vibrations on both the generator and turbine bearings were the result of mechanical unbalance on the generator, an enlarged turbine bearing clearance, and a hydraulic unbalance on the Francis turbine. The first step Powertech investigators took to improve the vibration readings on the generator and turbine was to [open quotes]compromise balance[close quotes] the generator. In this approach, the machine is mechanically unbalanced to counter magnetic unbalance. With the generator unbalance corrected, Powertech investigators recommended that the turbine bearing be inspected and reset to the design clearance of 14 mils (0.014 inch) diametrical. Resetting of the bearing resulted in significantly lower turbine vibration readings at high loads (less than 10 mils).
- OSTI ID:
- 5890669
- Journal Information:
- Hydro Review; (United States), Vol. 12:5; ISSN 0884-0385
- Country of Publication:
- United States
- Language:
- English
Similar Records
Adjustment of wicket gates important to maintaining machine performance
Seal rubs can cause shaft deflections