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|  YIL-G-24477(SHIPS)
4 .6.5 Governor tests.
4.6.5.1 Steady state speed regulation. Generator sets shall be tested as follows
for steady state speed regulation:
(a) At no load, and with manual or automatic control of generator excitation,
the generator set shall be adjusted to rated speed.
(b) The load shall be changed in 10.O percent increments from no load to 100
percent load and back to no load. At each point, the voltage shall be
adjusted to rated value and the speed shall be recorded.
(c) The speed regulation curve shall be plotted and furnished as part of the
test data.
4.6.5.2 Steady state governing speedband. At O, 25, 50, 75 and 100 percent rated
load, the steady state governing speedband shall be observed and recorded.
4.6.5.3 Momentary underspeed and overspeed. Momentary underspeed and overspeed tests
shall
be
conducted
as
follows:
(a) The generator set shall be adjusted to rated speed, voltage, and load. Rated
load shall then be removed in one step.
(b) The generator set shall be operated at rated speed, rated voltage, and no load.
A 100 percent resistance load shall then be suddenly applied in one step.
Readings of overspeed, underspeed, arid recovery time shall be recorded. The
(c)
method of measuring the speed changes and recovery time shall be approved
by the command or agency concerned. During these tests, manual or automatic .
control of generator excitation may be used. If manual control is used,
the no-load voltage for the underspend test shall be set at 105 percent of
rated voltage.
4.6.5.4 Overspeed trip. During the overspeed trip test, the regulating governor shall
be inoperative. The engine speed shall be increased above rated speed until the overspeed
trip acts to determine the r.p.m. at which the engine shall be shutdown.
4.6.6 Range of speed changer. Range of speed changer test shall be conducted as follows:
(a) At no load and with manual control of generator excitation, the generator set
shall be adjusted to rated speed and voltage. Operate the speed changer
so that the speed is at the minimum specified value.
Record speed. Operate
the speed changer so that the speed is at the maximum specified value.
Record speed and rate of change from minimum to maximum speed.
(b) At 100 percent load and with manual control of generator excitation, the
generator set shall be adjusted to rated speed and voltage. Operate the
speed changer so that the speed is at the minimum specified value. Record
speed. Operate the speed changer so that the speed is at the maximum
specified value. Record speed and rate of change. The load and voltage may
be maintained at rated valves when measurinq maximum speed.
4.6.7 Brush examination. During all tests, the performance of brushes should be noted
at each load point. Particularly, it should be noted if any injurious sparking occurs when
the entire load is dropped or applied in one step.
4.6.8 Generator voltage under manual control. Tests shall be conducted as follows
with the general field cold. the voltage regulator shall be made inoperative by position-
ing the manual-automatic voltage regulation switch in the manual position.
Operate the unit at a speed corresponding to no load. Adjust the manual
(a)
control so that the voltage is at the minimum specified value. Record
voltage and speed. Adjust the manual control so that the voltage is at the
maximum specified value. Record voltage and speed.
(b) Operate the unit at no load, and adjust the voltage to the minimum specified
valve. Add load (at rated p.f.) and adjust the voltage, Speed, and load
until the unit is operating at the minimum specified voltage with rated
load. Record voltage, current, and speed.
(c) Reduce the voltage and load to rated voltage and no load. Adjust the voltage
to the maximum specified value. Add load (at rated p.f.) and adjust voltage,
speed, and load until the unit is operating at the maximum specified voltage
with rated load. Record voltage, current, and speed.
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