Erratic Voltage Regulation; Overvoltage Condition - Kohler 24RCL Manual

4. Determine if the controller is damaged. With the
generator set running, disconnect P4 from the
RDC2 controller and measure the voltage between
pins P4--2 (+) and P4--1 (--).
a. If this voltage is greater than 3 VDC, connect an
ammeter between pins P4--2 (+) and P4--1 (--)
and measure the current that the RDC2
controller can provide.
b. If the current is greater than 50 mA, check the
leads between the RDC2 and the activator
board for short circuits or damaged wiring.
c. If the RDC2 controller is not able to source
greater than 3 VDC when P4 is disconnected or
is not able to source greater than 50 mA to an
ammeter, and the generator is shutting down
on undervoltage after starting (indicating that
the controller is trying to excite the field), it is
possible that the RDC2 controller is damaged.
5. Determine if the leads between the RDC2 and the
activator board are damaged. Reconnect P4 to the
RDC2 controller. Disconnect the plug, P17, at the
activator board and measure the voltage between
wire 3B (+) and 5B (--), P17-1 and P17-6.
a. If the voltage between 3B and 5B is greater
than 3 VDC, connect an ammeter between wire
3B (+) and 5B (--) and measure the current that
the RDC2 controller can provide.
b. If the current between 3B and 5B is greater than
50 mA and the generator does not output any
voltage with the activator board connected and
the line circuit breaker open, verify that the
activator board is working properly.
c. If the the voltage between 3B and 5B is not
greater than 3 VDC or is not able to source
greater than 50 mA to an ammeter, and the
generator is shutting down on undervoltage
after starting (indicating that the controller is
trying to excite the field), leads 3B and 5B may
be damaged.
6. To troubleshoot the activator board and the
alternator for low voltage, see the alternator
service manual.
6.1.2

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
80 Section 6 Component Testing and Adjustment
producing flicker. If flicker is observed, it can be caused
by any of the following:
Load Fluctuation
D
Engine speed fluctuation. Refer to Section 6.5 and
D
the engine service manual for troubleshooting.
Alternator fault. Refer to the alternator service
D
manual for troubleshooting.
Outer loop gain (Voltage Regulator Gain Adjust) too
D
high. Try decreasing to 1 to see if erratic fluctuations
stop. See Section 6.4.4.
Incorrect cut-in frequency or slope for the Volts/Hz
D
curve. Verify that the settings match the factory
defaults. See Section 6.4.3, Volts/Hz and Cut-In
Frequency.
Loose connection(s) in wiring to the Activator board
D
or RDC2 controller.
6.1.3

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 activator board
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 activator
board.
4. Refer to the Alternator Service Manual for
additional troubleshooting procedures.
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