TP-6811 7/16 77Section 6 Component Testing and Adjustment
6.2.2 Erratic Voltage Regulation
Dramatic variations in the alternator voltage (more than
5 VAC) while the generator is operating at a steady load
may cause flicker. Connect a flicker lamp to the
generator output to determine if the generator is
producing flicker. If flicker is observed, it can be caused
by any of the following:
D Load Fluctuation
D Engine speed fluctuation. Refer to Section 6.6 and
the engine service manual for troubleshooting.
D Rotating exciter board failure (single SCR or diode
failure) indicated by erratic voltage regulation being
load-dependent.
D Alternator fault. Refer to the alternator service
manual for troubleshooting.
D Outer loop gain (Voltage Regulator Gain Adjust) too
high. Try decreasing to 1 to see if erratic fluctuations
stop. See Section 6.5.4.
D Incorrect cut-in frequency or slope for the Volts/Hz
curve. Verify that the settings match the factory
defaults. See Section 6.5.3, Volts/Hz and Cut-In
Frequency.
D Loose connection(s) in wiring to the stationary L ED
board (SLB) or RDC2 controller.
6.2.3 Overvoltage Condition
The alternator field can be overexcited, causing
excessive output voltage. If this failure is observed,
ensure that the line circuit breaker is open and that no
customer loads can be damaged by continued testing of
this condition. Do not run the generator set for extended
periods of time in an overvoltage condition.
To further isolate the cause of an overvoltage condition:
1. Remove the connector from P4 on the RDC2
controller. If the overvoltage conditions clears (the
voltage should decay to a few volts), check the
voltage sensing wiring and verify the configuration
and metering accuracy of the RDC2 controller.
Check the system voltage setting and the voltage
calibration.
2. If the configuration in the controller is correct and
the voltage is being metered accurately (shuts
down for overvoltage) the RDC2 controller may be
damaged. Check the wiring and the SLB to
determine the cause of the controller failure.
3. If the overvoltage condition persists with P4
unplugged, check for both AC and DC voltage
between 3B (+) and 5B (-) of the disconnected P4.
If voltage is found, check the wiring to the SLB.
4. If no voltage is found between 3B (+) and 5B (-),
verify that the back cover from the alternator is
intact and that no light is reaching the
photoreceptor on the rotating exciter board.
5. Refer to the Alternator Service Manual for
additional troubleshooting procedures.
6.2.4 LED Optic Board Test Procedure
This procedure is also included in the alternator service
manual.
The following procedure provides information on testing
the alternator’s LED optic board. Certain steps require
that the generator set be running. When the generator
set is not running, disable the generator set. See the
safety precautions listed below. Disconnect all load
from the generator set during this test.
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