Generac Power Systems 53187 - Manual (Page 54)

SECTION 1.9
OPERATIONAL TESTS & ADJUSTMENTS
L
PARTI
THE REVOLVING FIELD AC GENERATOR
Operational Tests (Continued)
If AC output voltage and frequency are not w ithin
the stated lim its, som e adjustm ents w ill have to be
m ade as follow s:
□ If voltage and frequency are both correspondingly
high or low , check and adjust the engine governor.
□ If AC frequency is good, but voltage is high or low ,
try adjusting the Voltage Regulator.
NO TE: Do NO T attem pt an adjustm ent If the engine
Is running rough. If engine runs rough or Is hard to
start, air m ay be present In the diesel fuel system .
If necessary, bleed the fuel system as outlined In
PART 4, "ENGINE FUEL SYSTEM ".
NO TE: If problem s are encountered, refer to the
appropriate troubleshooting section In this m anual.
See Section 1.6 If troubleshooting units w ith 15
Inch stator. See Section 1.7 for troubleshooting
units w ith 10 Inch stator.
CHECK OPERATION UNDER LOAD:
Turn on electrical loads equal to the generator’s
rated w attage and/or am perage capacity. Engine
speed (frequency) m ay drop off m om entarily w hen load
is applied, but should recover w ithin a short tim e. W ith
the unit loaded to its rated capacity, frequency should
not droop below about 58 Hertz.
Engine Governor Adjustment
You m ay w ish to read Section 1.5, ‘INTRODUC­
TION TO TROUBLESHO OT INCr.
Initial adjustm ent of governed speed should be
accom plished at no-load condition. Prior to engine
startup, turn OFF all electrical loads by w hatever
m eans available (such as the generator m ain circuit
breakers).
To adjust the engine governor, proceed as follow s:
1. Connect an accurate AC frequency m eter and volt­
m eter to the proper generator leads.
2. Start the engine, let it stabilize and w arm up at
no-load.
3. Read the no-load AC frequency and voltage from the
previously connected m eters.
a. AC frequency at no-load should be 60.5-63.0
Hertz.
b. Line-to-line voltage should be 242-254 volts.
c. Line-to-neutral voltage should be 121-127 volts.
4. Analyze the voltage and am perage readings as
follow s:
a. If frequency and voltage are both good, no adjust­
m ent is needed.
b. If frequency is high or low , go on to Step 5 of this
test.
c. If frequency is good, but voltage is high or low ,
adjust the voltage regulator.
5. If no-load AC frequency is high or low , adjust the /
engine governor as follow s Rgure 1):
a. Turn the GOVERNOR ADJUSTING SCREW S as
required to obtain a no-load frequency as close as
possible to 62 Hertz.
b. W ith no-load frequency close to 62 Hertz, apply
an electrical load as close as possible to the unit's
rated load. If frequency drops below 58 Hertz, repeat
Step 5(a), but set the no-load frequency slightly
higher than 62 Hertz. DO NOT EXCEED 63.5
HERTZ.
c. Again load to the unit to its rated load capacity.
Frequency under load should not drop below 58
Hertz.
d. Continue to check frequency at no-load and under
rated load until frequency at rated load is 58 Hertz or
m ore. DO NOT EXCEED A NO-LOAD SPEED OF
63.5 HERTZ.
Figure 1. Engine Governor Adjustm ent
Voltage Regulator Adjustment
UNITS W ITH 10 INCH STATOR:
To obtain correct AC voltage w hen frequency is
correct, proceed as follow s (Rgure 2):
1. Make sure the unit’s no-load frequency is correct.
Readjust the engine governor, if necessary.
2. W hen frequency is correct, and w ith unit running at
no-load, slow ly tum the VOLTAGE ADJUST potentiom ­
eter on the voltage regulator until voltage is w ithin the
specified lim its.
a. Line-to-neutral voltage should be 121-127 volts.
b. Line-to-line voltage should be 242-254 volts.
CAUTION: Do NOT force the Regulator’s adjust­
ment potentiometer past its stops or damage to
the Regulator can result.___________________
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