Generac Power Systems IM Series - Manual (Page 22)

3. Start the generator engine, let it stabilize and warm up
at NO-LOAD.
Figure 14. Test Points fora-c Voitage/Frequency
4. Read the no-load a-c voltage and frequency. Indicated
readings should be 124 volts at 62 Hz.
Test Results:
A. Voltage and Frequency check GOOD: Go to Step 4.
B. Voltage and Frequency are both high or low: Go to
Step 5.
C. Low or no a-c voltage: Go to Step 6.
D. Frequency GOOD, Volts HIGH: Go to Step 10.
Step 4 • Check Load Voltage and Frequency
NOTE: If the no-load voltage and frequency were
within specified limits but operational problems
occur when electrical loads are applied, check the
a-c voltage and frequency under load.________________
Test Procedure: Proceed as follows:
1. Check that load leads are properly connected to a-c
output terminals T1 (red), T2 (white) and T3 (black).
2. Connect an accurate a-c voltmeter and frequency
meter to a-c output leads. Connect meters across leads
T1 (red) and T2 (white).
3. Start the generator engine, let it stabilize and warm up.
Then, turn ON electrical loads by whatever means
provided (such as doubie throw switch or circuit breaker).
Apply loads as dose as possible to the unit’s rated
maximum continuous wattage/amperage capacity.
4. With rated loads applied, check the a-c voitage and
frequency readings. Voitage shouid be at least 116 volts;
frequency should be at least 58 Hz (or higher).Test
Results: If voltage and frequency are good at no-load
but drop excessively when electrical loads are applied,
check the following.
A. Generator may be overloaded. Add up the wattage or
amperage of all electrical loads being operated at one
time. This total should be less than the generator’s rated
wattage/amperage capacity. Reduce electrical loading
as necessary.
B. A ground fault condition may exist in the generator or
on one or nwre connected electrical loads. This can
increase current flow dramatically and may cause circuit
breakers to trip. See INSULATION RESISTANCE
TESTS on Page 9.
C. Loss of engine power may have occurred. Check
engine for adequate air flow, clogged air cleaner, incor­
rect ignition timing, mechanical failure, incorrectly ad­
justed carburetor, etc. Complete repairs to engine as
necessary.
Step 5 - Check/Adjust Engine Governor
Test Procedure: If the no-load voltage and frequency
are both correspondingly high or low, adjustment of the
engine governor may be required. See ADJUSTMENTS
section. Following governor adjustment to the correct a-c
frequency, the a-c voltage must be checked. If engine
speed (frequency) is correct but a-c voltage is not, adjust­
ment of the Electronic Voltage Regulator may be re­
quired.
Test Results:
A. Voltage and Frequency are correct: STOP tests.
B. Voitage/Frequency still incorrect. Go to Step 6.
Step 6 - Check Field Boost Circuit
NOTE: Some "residual" magnetism Is normally
present in the Rotor (revolving field). This residual
magnetism should be adequate to create the neces­
sary "pickup" voltage In the Stator windings. For
that reason, failure of the Field Boost function will
not usually cause a problem unless the Rotor's
residual magnetism Is also lost.___________________
Test Procedure: Test the Field Boost circuit as follows
(Figure 15):
1. Disconnect Wires 4 from Pin 2 of the Choke Module
CM.
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