Operational Tests - Hobart JET-EX 4 Operation And Maintenance Manual

B. Operational Tests
(1) Start the engine as described in 1-3; Para. 3 (a), and let it warm at idle speed.
(2) Inspect for oil, fuel and coolant leaks.
(3) Check the engine ammeter (20, Fig. 1) for a slight charge. Check oil pressure gauge (1). It should
read 35 to 60 psi (240 to 414 kPa). Check coolant temperature gauge. It should read 180 to 200 deg.
F (82 to 93 deg. C.).
(4) Idle speed displayed on the tachometer (2) should be 900 to 1000 RPM.
(5) Check engine rpm's at operating speed:
(a) Governor
Place speed control switch (13) in RATED RPM (up) position. Tachometer (2) should show a
reading of 2600 rpm at no load speed.
(6) Depress the PUSH TO BUILD UP VOLTAGE Switch to build up output voltage of generator.
(7) Set current limit control (4, Figure 1) to maximum, full clockwise, position.
(8) Adjust the load bank for a load of 550 amperes.
(9) Place the contactor control switch (11) in the CLOSE position. CONTACTOR CLOSED light (12)
will glow and the contactor will close. Release the switch to the center ON position. The tachometer
(2) will indicate 2550 + 25 RPM.
(10) Disconnect the load bank and check the overvoltage protection by adjusting voltage regulator po-
tentiometer R46 (1, Fig. 3) to increase the voltage. The overvoltage relay will trip and open the load
contactor at 32 to 34 volts in 2 to 10 seconds.
(11) Readjust the voltage to 28.5 volts, connect the load bank, set it at 550 amperes, and close the
contactor.
(12) Remove load bank and check voltage regulation at no load. Voltage will be 28.5 volts. Reconnect
load bank and check voltage regulation with load bank set at 137, 275, 413, 550, and 660 amperes
and check voltage at each setting. Voltage will be 28.5 + 1 volts at each different load.
(13) Apply 600 to 700 amperes load to the generator and set the current limit control (4) to 400. Cur-
rent displayed on ammeter (6) will be 400 + 40 amperes.
NOTE: Voltage will not drop below 12 volts.
(14) Set current limit control to 1000. Apply 1200 amperes load. Current dispalyed on ammeter will be
1000 + 100 amperes and voltage will not drop below 12 volts.
(15) To check the overspeed relay, manually override the governor linkage at the ignition circuit and
shut down the engine at 3100 to 3200 RPM.
(16) Restart the engine, check the instruments as directed in step (3), and check the entire generator
set for unusual vibration and noises.
May 20/89
OM-2049
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