Oil or water leaks.
With full pressure and flow, check threaded and flanged joints
of the various water lines to the unit for leaks. Check oil piping and bearing oil tubs
for leaks at joints.
When the unit checkout has been completed and the clearance for the overhaul
released, the unit can be watered up for startup. Maintenance personnel should be
stationed with two-way radios at strategic locations near the unit to listen and watch
for anything unusual when the unit is started. The wicket gates should be opened
just enough to start the unit turning and then shut. This should be done several
times to check for "rubs" or other problems. If no problems are noted, the wicket
gates should be opened to bring the unit to 100-percent speed. If at any point any
of the observers notice any unusual noise or other problems, they should notify the
operator to immediately shut the unit down. If no problems are noted, the unit
should continue to operate at speed-no-load until bearing temperatures stabilize.
If the governor was not adjusted before startup, it is possible that the unit will
"hunt." If this is the case, gradually close the governor dashpot needle until the
hunting stops. The governor can be adjusted for optimum response after the bearing
Once it is determined that the unit can be operated with no problems, the following
readings should be taken and compared to the preteardown readings. It is very
likely that, depending on what modifications have been made to the unit, a great deal
of other testing besides these readings will be required. These readings are
suggested only as basic indication of the unit's condition. Various index or
acceptance tests, as well as numerous tests of the electrical equipment, will be
required following any uprate or major overhaul.
Bearing heat run.
With the unit running at speed-no-load, the bearing metal
and oil temperatures should be recorded until the temperatures stabilize. If a
data logger is not available, the temperatures should be recorded manually every
5 minutes for the first 30 minutes of operation and every 15 minutes after that
until the temperatures stabilize. After the unit is brought online, again monitor
temperatures as the unit is loaded.
Shaft runout readings.
The runout readings can be taken with dial indicators
but are much more meaningful if taken by proximity probes. Readings should be
taken at various loads from speed-no-load to full load. Special attention should
be given to the runout at any rough zones the turbine may have. If proximity
probes are used, the signal should be recorded with a strip chart recorder so that
the wave form of the runout can be analyzed. A normal runout