GE A4021 - Manual (Page 11)

AUTOMATIC LOW OIL
PRESSURE SHUTDOWN
The engine is equipped with a normally-open (N.O.)
oil pressure switch (Figure 4). Engine oil pressure
holds the switch open during cranking and operation.
Should oil pressure drop below about 8-10 PSI, the
switch contacts close and the engine automatically
shuts down.
Figure 4 — Switches for Engine Safety Shutdown
HIGH TEMPERATURE SHUTDOWN
An oil temperature switch (Figure 4) with normally-
open (N.O.) contacts is mounted near the oil filter. If
oil temperature were to exceed a preset temperature,
the switch contacts close and the engine shuts down.
FIELD BOOST
The Controller Circuit Board Houses a field boost
diode and resistor which are not part of the automatic
choke circuit. These two components are part of a
“field Boost’ circuit (Figure 5). During engine crank­
ing only, a positive DC (battery) voltage is delivered
through the diode, resistor, brushes and slip rings,
and to the generator rotor. Application of this voltage
to the rotor “flashes the field” whenever it is started.
Flashing of the field each time the generator starts
makes sure that a sufficiently strong magnetic field is
available to produce the required “pick up” voltage in
the stator windings.
Figure 5 — Field Boost Circuit
OVER VOLTAGE PROTEaiON
A solid state voltage regulator (Figure 6) controls the
generator’s AC output voltage. This regulator sup­
plies an excitation current to the rotor. By regulating
the rotor’s excitation current, the strength of its mag­
netic field is regulated and, in turn, the voltage deliv­
ered to connected electrcal loads is controlled. When
the AC frequency is 60 Hz, voltage is regulated at 120
volts (voltage-to-frequency ratio is 2-to1).
Figure 6 — Solid State Voltage Regulator
SENSING
0» ■ ■4(»U TO ROTOR
Oa.O<-)—/(DIRECT CURRENT)
&-2—] FROM STATOR
EXCfTATtON WINDING
(ALTERNATtNG CURRENT)
The voltage regulator also incorporates a “voltage
surge protection circuit.” This circuit prevents trouble­
some surges in the generator AC output voltage.
Voltage surge is a common cause of damage to elect-
tronic equipment.
25-HOUR BREAK IN PERIOD
The first 25 hours of operation are for “breaking in”
the new generator. Correctly breaking in the genera­
tor is essential to minumize fuel consumption and pro­
vide maximum engine performance. During this 25-
hour break in period, comply with the following:
• Run the unit at varying electrical loads, to help seat the
engine piston rings properly.
• For the 75 hours of operation after the “break in” period,
avoid light electrical loads. Load the generator at 50% (or
more) of its rated wattage capacity. Repeated light loads
during the break in period can cause improper seating of
engine piston rings, which could cause blowby and high
oil consumption.
• During the break in period, check engine oil level fre­
quently. It is normal for oil consumption to be high during
the breaking in period.
• After the 25-hour break in period, complete the tasks rec­
ommended under “25-Hour Check Up.”
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