Generac Power Systems 004709-0 owner manual Additional Information, ‹ 2.9.3 Field Boost

Section 2 – Operation

Recreational Vehicle Generator

‹2.9.3 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 2.3). During engine cranking only, a positive DC (battery) voltage is delivered through the diode, resistor, brushes and slip rings, 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 “pickup” voltage in the stator windings.

Figure 2.3 – Field Boost Circuit

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.

2.10 ADDITIONAL INFORMATION

‹2.10.1 ATTENTION REQUIRED AFTER SUBMERSION

If the recreational vehicle generator has been sub- merged in water, it MUST NOT be started and oper- ated. Following any submersion in water, have an Authorized Service Dealer thoroughly clean and dry the generator.

‹2.9.4 OVERVOLTAGE PROTECTION

A solid-state voltage regulator (Figure 2.4) 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 60 Hertz, voltage is regulated at 120 volts (voltage-to-frequency ratio is 2-to-1).

Figure 2.4 – Solid State Voltage Regulator

‹2.10.2 OPERATION IN HIGH GRASS OR BRUSH

Never operate the generator while the vehicle is parked over high grass, weeds, brush, leaves or any other combustible substance. Such materials can ignite and burn from the heat of the exhaust system. The generator exhaust system becomes extremely hot during operation and remains hot for a long time after it has shut down.

‹2.10.3 EFFECTS OF MOISTURE AND DIRT

Keep the generator set as clean and dry as possible. Protect the unit against excessive dust, dirt, corrosive vapors, road splash, etc. Permitting dirt and mois- ture 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 problems. Dirt will make the problem worse, since dirt tends to hold moisture in contact with windings. Salt (as from sea air) also will worsen the problem since it tends to absorb moisture from the air. Salt and moisture, when combined, form a good electrical conductor.

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