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Adjustments
ELECTRIC GOVERNOR ADJUSTMENT
Generator frequency is in direct ratio to engine speed
which is controlled by the governor. The generator set
uses a Cummins model EFC electric governor.
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FIGURE 15. EFC GOVERNOR CONTROL
The governor control has four potentiometers for mak¬
ing adjustments.
Gain
The gain control is a one-turn potentiometer. It is used to
adjust the sensitivity of the governor. A clockwise rota¬
tion of the potentiometer will shorten the response time
to load changes.
Droop
The Droop control is a one-turn potentiometer. It is
adjustable for zero % (isochronous) to 5% speed droop.
Fully counterclockwise rotation will decrease the speed
droop.
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Idle Speed
The Idle Speed control is a 20-turn potentiometer for
adjusting the idle speed. A clockwise rotation will
increase the idle speed.
Run Speed
The Run Speed control is a 20-turn potentiometer for
setting the desired no-load governed speed. A clock¬
wise rotation will increase the run speed.
Preliminary Adjustments
1. Idle Speed potentiometer.
a. Turn the screw counterclockwise 20 turns.
b. Turn the screw clockwise 10 turns.
c. This will set the idle speed potentiometer to its
mid position.
2. Run Speed potentiometer.
a. Turn the screw counterclockwise 20 turns.
b. Turn the screw clockwise 10 turns.
c. This will set the run speed potentiometer to its
mid position.
3. Gain potentiometer
a. Turn the screw fully counterclockwise.
4. Droop potentiometer
a. Turn the screw fully counterclockwise for
isochronous operation.
b. Turn the screw to approximately 40 for 3 per¬
cent droop.
c. Turn the screw to approximately 80 for 5 per¬
cent droop.
Governed Speed Adjustment
Generators which are to operate at 60 Hz full load, must
have the engine no load governed speed adjusted to:
60.0 Hz (1800 RPM) for isochronous operation
61.8 Hz (1854 RPM) for 3% speed droop
63.0 Hz (1890 RPM) for 5% speed droop
For generators which are to operate at 50 Hz full load,
the engine no-load governed speed must be adjusted
to:
50.0 Hz (1500 RPM) for isochronous operation
51.5 Hz (1545 RPM) for 3% speed droop
52.5 Hz (1575 RPM) for 5% speed droop
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