Generac 00919-0 Field Boost, Automatic LOW OIL Pressure Shutdown, Overvoltage Protection

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® GENERACCORPORATION

Generac NP-50LPG Recreational Vehicle Generator

Induction type motors (such as those that run the vehicle’s furnace fan, refrigerator, air conditioner, etc.) need about 2- 1/2 time more watts of power for starting than for running (for a few seconds during motor starting). Be sure to allow for this when connecting electrical loads to the generator. First, figure the watts needed to start electric motors in the system. To that figure, add the running wattages of other items that will be operated by the generator.

Do not apply heavy electrical loads for the first two or three hours of operation.

ADDITIONAL INFORMATION

FIELD BOOST

The Controller Circuit Board houses a field boost diode and resistor which are part of a “field boost” circuit (Figure 5). During engine cranking only, a positive DC (battery) voltage is delivered 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 suffi- ciently strong magnetic field is available to produce “pick-up” voltage in the stator windings.

This section discusses some the the engine protective devices,

Figure 5 — Field Boost Circuit

overload protection and breaking in a new generator.

 

 

AUTOMATIC LOW OIL PRESSURE

SHUTDOWN

The engine is equipped with a normally-closed (N.C.) oil pres- sure switch (Figure 4). Engine oil pressure holds the switch open during cranking and operation. Should oil pressure drop below a pre-set level, the switch contacts close and the engine automatically shuts down.

HIGH TEMPERATURE SHUTDOWN

 

A temperature switch (Figure 4) with normally-open (N.O.) con-

OVERVOLTAGE PROTECTION

tacts is mounted near the oil filter. If engine temperature were

to exceed about 284°F (140°C), the switch contacts close

A solid state voltage regulator (Figure 6) controls the gener-

and the engine shuts down.

ator’s AC output voltage. This regulator supplies an excitation

Figure 4 — Switches for Engine

current to the rotor. By regulating the rotor’s excitation cur-

rent, the strength of its magnetic field is regulated and, in

Safety Shutdown

turn, the voltage delivered to connected electrical loads is

 

HIGH TEMPERATURE

controlled. When the AC frequency is 60 Hz, voltage is reg-

SWITCH

ulated at 120 volts (voltage-to-frequency ratio is 2-to-1).

 

Figure 6 — Solid State Voltage Regulator

LOW OIL PRESSURE SWITCH

 

R e c r e a t i o n a l V e h i c l e G e n e r a t o r

 

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Contents Generac Generac NP-50LPG Recreational Vehicle Generator Reference Number Identification 20-29 HOW to Obtain Service Operation and MaintenanceRead this Manual Thoroughly Generator Applicability InstallationSafety Generator AC Connection SystemFuse START/STOP SwitchFuel Primer Main BreakerBefore Starting the Engine Starting the GeneratorStopping the Generator Applying Loads to GeneratorAutomatic LOW OIL Pressure Shutdown Field BoostOvervoltage Protection Hour Check UP Operating PrecautionsHour Break in Period Effects of Moisture and DirtFuel Consumption SpecificationsFuel Requirements Engine OIL RequirementsChecking Engine OIL Level Change OIL FilterEngine AIR Cleaner Clean or Replace AIR FilterBattery Cleaning the GeneratorSpark Arrestor Muffler Drive Belt OUT of Service ProtectionReturn the Unit to Service After Storage Exercising the GeneratorProblem Cause CorrectionElectrical Data Drawing NoElectrical Data Exploded View Base and Pulleys Repair Parts Base and Pulleys Description QTYExploded View Alternator and Panel Repair Parts Alternator and Panel Exploded View Engine Enclosure Repair Parts Engine Enclosure QTY DescriptionExploded View GN-410 Engine Drawing No. B2195Repair Parts GN-410 Engine Exploded View Engine Accessories Repair Parts Engine Accessories California Emission Control Warranty Statement Emission Control System Warranty Three Year Warranty Schedule