12-11. OIL PRESSURE ALARM AND SHUTDOWN SWITCH OP1/OP2.
General. The oil pressure alarm and shutdown switch OP1 /OP2 shuts down the engine when the oil pressure
drops below the safe limit.
b. Apparatus. The following equipment is required to perform this test:
Oil pressure gage accurate to + percent.
Flexible oil line.
Preparation for test. With set not operating remove OP1/OP2 from the engine block and reconnect as
shown in Figure 12-4, with OP1/OP2 and oil pressure gage in approximately the same horizontal plane as
OP1/OP2 tap located on the engine (Figure 12-1). Remove the oil filler cap, and insert the open end of the
flexible oil line in the filler tube.
With the bleeder valve dosed and the shut-off valve in the oil pressure line open, start and
operate the set at rated speed and no load.
Open the bleeder valve slightly to purge air from the system.
Close the bleeder valve and record the oil pressure as indicated on the test gage.
Almost completely dose the shut-off valve.
Slowly open the bleeder valve until OP1/OP2 actuates the warning light and shuts down the
engine. Record the oil pressure when the warning light is actuated, and at the point of set
Results. Compare the value of the warning and shutdown pressure with the requirement of Table 12-3.
12-12. COOLANT TEMPERATURE SWITCH WT2.
General. The coolant temperature switch WT2 must be capable of protecting the engine in the set against
overheating for any reason.
Apparatus. Instrumentation for measuring engine temperatures and ambient temperatures shall be in
accordance with paragraph 12-3.
Preparation for test.
Connect the load instrumentation in accordance with 12-5.
Install the thermocouple and gage to measure the same temperature detected by WT2 (Figure 12-1).
Start and operate the generator set at rated voltage, rated frequency (speed), and rated load.
Close the radiator louvers.
If the engine falls to shut down when the temperature exceeds the maximum trip value
specified in Figure 12-3 the test shall be Immediately discontinued.
Continuously monitor the temperature on the thermocouple installed gage. Record the temperature at
which the coolant temperature indicator illuminates. Record the temperature at which WT2 actuates.
Results. The warning and trip points shall be in accordance with Table 12-3.