Graphic representations shall include the actual instrument trace
of voltage and frequency showing: charts marked at start of test;
observed steady-state band; mean of observed band; momentary
overshoot and undershoot (generator terminal voltage and
frequency) and recovery time for each load change together with
the voltage and frequency maximum and minimum trace excursions for
each steady state load condition prior to and immediately
following each load change. Generator terminal voltage and
frequency transient recovery time for each step load increase and
decrease.
(1.) Perform and record engine manufacturer's recommended
prestarting checks and inspections.
(2.) Start the engine, make and record engine manufacturer's
after-starting checks and inspections during a reasonable warm-up
period and no load. Verify stabilization of voltage and frequency
within specified bandwidths.
(3.) With the unit at no load, apply the Maximum Step Load
Increase.
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NOTE: For applications where the Maximum Step Load
Increase is 100%, delete steps 4., 5., and 6.
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(4.) Apply load in steps equal to the Maximum Step Load Increase
until the addition of one more step increase will exceed the
Service Load.
(5.) Decrease load to the unit such that addition of the Maximum
Step Load Increase will load the unit to 100% of Service Load.
(6.)
Apply the Maximum Step Load Increase.
(7.) Decrease load to zero percent in steps equal to the Maximum
Step Load Decrease.
(8.)
Repeat steps 3. through 7.
j.
Test Voltage Unbalance with Unbalanced Load (Line-to-Neutral) to
the performance criteria specified in paragraph GENERATOR.
Prototype test data is acceptable in lieu of the actual test.
This test may be performed using any prime mover.
(1.) Start and operate the generator set at rate voltage, no
load, rated frequency, and under control of the voltage regulator.
Read and record the generator frequency, line-to-neutral
voltages, and the line-to-line voltages.
(2.) Apply the specified load between terminals L1-L2, L2-L0, and L
3-L0 in turn. Record all instrument readings at each line-neutral
condition.
(3.) Express the greatest difference between any two of the
line-to-line voltages and any two of the line-to-neutral voltages
as a percent of rated voltage.
SECTION 16263A
Page 71
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