Generac Power Systems A-2624 - Manual (Page 9)

25 HOUR CHECK-UP PERtOD
After the first 25 hours of operation have been com­
pleted, contact an Authorized Service Facility for the
following maintenance. The Owner/Operator is
responsible for any changes.
• Change engine crankcase oil and oil filter.
• Check all cooling system ventilation openings.
• Check engine carburetor adjustments.
• Check engine ignition system.
• Inspect the entire electrical system.
• Inspect the engine exhaust system.
AHENTION REQUIRED AFTER
SUBMERSION
If the generator has been submerged in water, it must
NOT be started or operated. Following any submersion
in water, have an authorized Generac Service Facility
thoroughly clean and dry the generator.
EFFECTS OF MOISTURE AND DIRT
Keep the generator set as clean and dry as possible.
Protect unit against excessive dust, dirt, corrosive
vapors, road splash, etc. Permitting dirt and moisture
to accumulate on generator windings will have an
adverse effect on the insulation resistance of those
windings.
When moisture is allowed to remain in contact with
windings, some of the moisture will be retained in voids
and cracks in the insulation. This causes a reduced
insulation resistance and will eventually cause prob­
lems. Dirt will make the problem worse, since dirt tends
to hold moisture in contact with windings. Salt (as from
sea air) will also worsen the problem since it tends to
absorb moisture from the air. Salt and moisture, when
combined, form a good electrical conductor.
AUTOMATIC LOW OIL PRESSURE
SHUTDOWN
The engine is equipped with a normally-closed (N.C.)
oil pressure switch (Figure 5). Engine oil pressure
holds the switch open during cranking and operation.
Should oil pressure drop below about 8-10 psi, the
switch contact? close and the engine automatically
shuts down.
Figure 5 — Oil Pressure and Temperature Switches
High
Temperature
Switch
Oii
Pressure
Switch
HIGH TEMPERATURE
SHUTDOWN
A temperature switch (Figure 5) with normally-open
(N.O.) contacts is mounted on the engine. Should
engine temperature exceed about 284°F (140°C), the
switch contacts close and the engine shuts down.
FIELD BOOST
The controller Circuit Board houses a field boost diode
and resistor. These two components are part of a
“field boost" circuit (Figure 6).
Figure 6 — Field Boost Circuit
CLOSEST TO
BEARING
During engine cranking only, a positive DC (battery)
voltage is delivered through the diode, resistor, brush­
es and slip rings, and to the generator rotor.
Application of this voltage to the rotor ‘Hashes 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.
OVER VOLTAGE PROTECTION
A solid state voltage regulator (Figure 7) controls the
generators AC output voltage. This regulator supplies
an excitation current to the rotor. By regulating the
rotor’s excitation current, the strength of its magnetic
field is regulated and, in turn, the voltage delivered to
connected electrical loads is controlled. When the AC
frequency is 60 Hz, voltage is regulated at 208 volts, 3-
phase.
Figure 7 — Solid State Voltage Regulator
-SENStNO
-4<*Hj_TOROTOW
(DRECT CURRENT)
FROM STATOR
EXCITATION WWDtNO
(ALIERNATINO CURREKT]
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 elec­
tronic equipment.
— 9 —