Generac Power Systems 941-2, 940-2 Section SHUTDOWN FEATURES, Oil Pressure Switch, General

Section 6.5

SHUTDOWN FEATURES

GENERAL

The engine mounts an Oil Pressure Switch (LOP) and an Oil Temperature Switch (HTO). These two switch- es, in conjunction with the A6060 circuit board, pro- tect the engine against (a) low oil pressure and (b) high oil temperature.

The engine protective circuit Is shown in Figure 1.

OIL PRESSURE SWITCH

DESCRIPTION:

The Oil Pressure Switch has normally-closed contacts which are held open by engine oil pressure during cranking and running. Should oil pressure drop below approximately 5 psi, the switch contacts will close to complete the Wire 85 circuit to ground. A6060 circuit board action will then de-energize the Wire 14 circuit and the engine will shut down.

The A6060 circuit board provides a time delay to allow oil pressure to build during startup, to prevent premature shutdown.

TESTING THE SWITCH:

Use a volt-ohm-milliammeter (VOM) to test the oil pressure switch. Connect the VOM test leads across the switch terminal and the switch body. With the engine shut down, the meter should read "continuity" (a very small resistance is acceptable). With engine running, the meter should read "infinity".

OIL TEMPERATURE SWITCH

DESCRIPTION:

This thermostatic switch has normally-open contacts. Should engine oil temperature exceed a preset safe value (about 293° F.), the switch contacts will close. On closure of the Switch contacts, the Wire 85 circuit will be connected to frame ground. Engine shutdown will then occur.

Figure 1. Engine Protective Circuit

Figure 2. Engine Protective Devices

Figure 3. Testing the Oil Temperature Switch

TESTING:

See Figure 3. Remove the switch and place its sens- ing tip into oil. Place a thermometer Into the oil. Connect the test leads of a VOM across the switch terminals. The meter should read "Infinity". Heat the oil. When oil temperature reaches approximately 287°-296° F. (142°-147° C.), the meter should read "continuity" (a small resistance is acceptable).

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