Generac Power Systems 004992-0, 004992-1 Generator Fuel System, 1.7ENGINE PROTECTIVE DEVICES

Section 1 - General Information

Guardian 40kW Liquid-cooled Generators

1.6 GENERATOR FUEL SYSTEM NOTE:

The unit has been factory tested and adjusted using a natural gas fuel system. If propane (LP) gas is neces- sary, refer to Section 1.12 for conversion.

Fuel pressure for a natural gas set up should be five inches to 14 inches of water column (0.18 to 0.5 psi) at all load ranges.

Fuel pressure for an LP vapor set up should be 11 inches to 14 inches of water column (0.4 to 0.5 psi) at all load ranges.

NOTE:

A seperate gas line and regulator may be needed to assure proper gas pressure to the generator. Improper gas pressure can cause hard starting and affect engine durability.

Gaseous fuels such as natural and LP

!(propane) gas are highly explosive. Even the slightest spark can ignite such fuels and cause an explosion. No leakage of fuel is permitted. Natural gas, which is lighter than air, tends to collect in high areas. LP gas is heavier than air and tends to settle in low areas.

1.7ENGINE PROTECTIVE DEVICES

The engine has several safety switches which cause the engine to automatically shut down under the fol- lowing conditions: low oil pressure, high coolant tem- perature, engine overspeed, low coolant level or over- crank (Figure 1.3).

Figure 1.3 - Engine Protective Devices

Low Oil Pressure Switch

High Coolant

Temperature Switch

Low Coolant

Level Sensor

‹1.7.1 LOW OIL PRESSURE SWITCH

This switch is normally-closed (N.C.) but is held open by engine oil pressure during engine running. Should operating oil pressure drop below about 8-10 psi (55-68 kPa), the switch contacts close, the engine shuts down automatically, and the low oil pressure LED is turned ON (Figure 1.4).

The Low Oil Pressure, High Coolant Temperature and Low Coolant Level are not monitored for the first 10 seconds of engine run time.

Figure 1.4 - Low Oil Pressure Switch

‹1.7.2 HIGH COOLANT TEMPERATURE SWITCH

Normally open (N.O.) thermostatic switch has sens- ing tip which is immersed in captive coolant. Should coolant temperature exceed about 230°F (110°C), the switch contacts close. This causes the engine to shut down automatically and turns on the high coolant temperature/low coolant level LED (Figure 1.5).

Figure 1.5- High Coolant Temperature Switch

‹1.7.3 LOW COOLANT LEVEL SWITCH

Should engine coolant level drop below the level of the high coolant temperature switch, it is possible for the engine to overheat without automatic shutdown. To prevent such overheating without automatic shut down, the engine has a low coolant level sensor. If the engine coolant drops too low, the engine automatical- ly shuts down and turns on the high coolant temper- ature/low coolant level LED (Figure 1.6 on page 6).

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