8-9
GOVERNOR
The governor controls engine speed, which directly
affects the frequency and voltage output of the gen-
erator. The governor reacts to the speed/frequency
differential between no-load and full-load condi-
tions, known as “droop”. Good overall governor op-
eration requires a proper amount of governor
droop. Too large a droop, and genset voltage/fre-
quency control may be adversely affected. Too
small a droop may cause erratic governor action or
alternately increase and decrease engine speed,
“hunting” for the proper speed.
Governor Adjustments
This procedure is used to adjust the governor to
bring frequency and voltage within the specified
range, and to set governor stability.
WARNING
Contact with moving parts can
cause severe personal injury. Keep clothing,
hair, jewelry, and fingers clear when adjusting
the governor.
WARNING
A hot genset can cause severe
burns. Always allow the genset to cool before
touching any components or removing any
parts.
CAUTION
An accurate voltmeter, frequency
meter and a load bank capable of providing a
load of 4000 watts are needed to properly set the
governor adjustments.
Equipment required for governor adjustment in-
cludes:
• Digital frequency/voltmeter with 0.3% frequen-
cy accuracy, 0.5% voltage accuracy. Recom-
mended: Fluke 8060A or 85 series
• Digital ammeter. Recommended: Beckman
4410
• Variable load bank with 4 kW capacity
Connect an accurate voltmeter,ammeter and fre-
quency meter to the generator. A small speed drop,
not noticeable without instruments, will cause an
objectionable voltage drop.
If a carburetion problem is suspected, make certain
that the carburetor is adjusted correctly before at-
tempting to adjust the governor (see the
Gasoline
Fuel System
section on Page 8-11).
A binding governor shaft, governor linkage, or car-
buretor throttle will cause hunting. Also a fouled
spark plug can cause missing and hunting. Check
for these conditions before making governor adjust-
ments.
CAUTION
Voltage/frequency-sensitive equip-
ment such as VCRs, televisions, computers,
etc. may be damaged by power line frequency
variations. Some solid-state devices are pow-
ered whenever connected to an AC outlet even
if the device is not in actual operation. For this
reason, disconnect all devices which are volt-
age or frequency-sensitive before attempting
any carburetor/governor adjustments. If dis-
connecting the devices is not possible, open
the circuit breaker(s) at the distribution panel or
at the genset, if so equipped.
Adjustments to the governor should be made in the
following sequence.
1. Run the genset at least 10 minutes at 50% to
75% of its rated load. Check that the choke is
completely open. If the governor is completely
out of adjustment, make a preliminary adjust-
ment at no load to attain a safe voltage and
speed operating range.
2. Check the governor linkage for binding or ex-
cessive looseness. Check the motion spring for
bending or damage and straighten or replace
as needed.
3. With unit operating at no-load, adjust the speed
adjustment screw (see Figure 8-7 on Page
8-10) on the governor linkage to obtain 62 Hz,
and 127.5
4.5 volts. Set 50 hertz units to ob-
tain 52.0
0.5 Hz at between 220 and 231
volts for 220 volt units and 240 to 252 volts for
240 units. To increase the engine speed, turn
the adjustment screw clockwise. To decrease
the engine speed, turn the adjustment counter-
clockwise.
4. Check the frequency and voltage first with a
load applied and then with no load applied. The
frequency and voltage should stay within the
limits shown in Table 8-1 on Page 8-10.
5. Adjust the governor sensitivity to give the clos-
est regulation (least speed and voltage differ-
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