10
Table 1.--Tolerances for vertical hydrounit assembly
1
Measurement
Tolerance
Stator air gap
± 5% of nominal design air gap
Stator concentricity
(Relative to turbine guide bearing)
(Relative to turbine guide bearing)
5% of nominal design air gap
Upper generator guide bearing concentricity
(Relative to turbine and lower
generator guide bearing)
(Relative to turbine and lower
generator guide bearing)
20% diametrical bearing clearance
Lower generator guide bearing concentricity
(Relative to turbine and upper
generator guide bearing)
(Relative to turbine and upper
generator guide bearing)
20% diametrical bearing clearance
Seal ring concentricity
(Relative to turbine guide bearing
and each other)
(Relative to turbine guide bearing
and each other)
10% diametrical seal ring clearance
Circularity of stator
± 5% of nominal design air gap
Circularity of rotor
± 5% of nominal design air gap
Stator verticality
(Relative to plumb)
(Relative to plumb)
± 5% of nominal design air gap
Rotor verticality
(Relative to generator shaft)
(Relative to generator shaft)
± 5% of nominal design air gap
Shaft Straightness
Static shaft runout
(Orbit diameter)
(Orbit diameter)
No reading point deviates more than 0.003 inch
from a straight line connecting the top and bottom
reading point.
from a straight line connecting the top and bottom
reading point.
0.002 inch multiplied by the length of the shaft from
the thrust bearing to the point of runout
measurement divided by the diameter of the thrust
runner. All measurements in inches.
the thrust bearing to the point of runout
measurement divided by the diameter of the thrust
runner. All measurements in inches.
Plumb of center of shaft runout
0.000025 multiplied by the length of the shaft from
the highest plumb reading to the lowest plumb
reading.
the highest plumb reading to the lowest plumb
reading.
Distance from wicket gate to unit center
(® - figure C1)
(® - figure C1)
± 0.0002 X R
Distance between wicket gates
(D - figure C1)
(D - figure C1)
± 0.0001 X D
Plumb of wicket gates
20% of minimum diametrical wicket gate bushing
clearance
clearance
Parallelism of facing plates
20% of total (top + bottom) wicket gate clearance
Levelness of facing plates
2
20% of total (top + bottom) wicket gate clearance
1
These tolerances are intended to be used when manufacturer's tolerances are not available. Always
consult the equipment manufacturer first, if possible. This table is based on the table "Bureau of Reclamation Plumb
and Alignment Standards for Vertical Shaft Hydrounits," by Bill Duncan, May 24, 1991.
and Alignment Standards for Vertical Shaft Hydrounits," by Bill Duncan, May 24, 1991.
2
Plumb of wicket gate and levelness of facing plates can be outside these tolerances as long as the facing
plates meet the criteria for parallelism and the gates are within 20 percent of the minimum diametrical wicket gate
bushing clearance of being perpendicular to the facing plates.
bushing clearance of being perpendicular to the facing plates.