10 Generac®Power Systems, Inc.
Section 2 – Operation
PRIMEPACT 55G and 55LP Recreational Vehicle Generators
2.8.2 HIGH TEMP ERATURE SWITCH
This switch (Figure 2.3), which has normally open
(N.O.) contacts, is mounted near the oil filter. The
contacts close if the temperature should exceed
approximately 284º F (140º C), initiating an engine
shutdown.

Figure 2.3 – Low Oil Pressure and

High Temperature Switches

2.8.3 FIELD BOOST
The Controller Circuit Board houses a field boost
diode and resistor that are not part of the automatic
choke circuit. These two components are part of a
“field boost” circuit (Figure 2.4). During engine
cranking only, a positive DC (battery) voltage is deliv-
ered through the diode, resistor, brushes and slip
rings, and 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 “pickup” voltage in the
stator windings.

Figure 2.4 – Field Boost Circuit

2.8.4 OVERVOLTAGE PROTECTION
A solid-state voltage regulator (Figure 2.5) 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 electrical loads is controlled. When
the AC frequency is 50 Hertz, voltage is regulated at
115 volts.

Figure 2.5 – Solid State Voltage Regulator

The voltage regulator also incorporates a “voltage
surge protection circuit.” This circuit prevents trou-
blesome surges in the generator AC output voltage.
Voltage surge is a common cause of damage to elec-
tronic equipment.
2.8.5 25-HOUR BREAK-I N PERIOD
The first 25 hours of operation is the break-in period
for the generator. Properly breaking in the generator
is essential to minimize fuel consumption and pro-
vide maximum engine performance. During this 25-
hour break-in period, follow this procedure:
• Run the unit at varying electrical loads to help seat
the engine piston rings properly.
• Check the engine oil level frequently. Add oil if
needed. It is normal for the generator engine to
consume more oil than is normal until the piston
rings have properly seated.
• For the 75-hour operation following the break-in
period, avoid light electrical loads. Load the
generator at 50 percent (or more) of its rated
wattage capacity. Repeated light loads during these
75 hours can cause improper seating of engine pis-
ton rings, resulting in blowby and high oil con-
sumption.
• After operating the unit for 25 hours, complete the
tasks recommended under Section 2.8.6.
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