Discontinue Power Delivery With Unit Shutdown; Normal Conditions; Emergency Conditions - Hobart 90CU24 Operation And Maintenance Manual

OM-2084 / Operation and Maintenance Manual
90CU24 / Series 500392 Generator Sets
(4) A condition of overvoltage, undervoltage, underfrequency, overfrequency, or overload in the
output circuit will automatically open the load contactor and turn on the applicable indicating light
to signal the operator which of the above faults caused the protective monitor system to operate.
After the fault has been corrected, press the test/reset push button switch (19, Fig. 1) to turn off
the indicating light and reset the protective relay system. Proceed with power delivery by
operating the load contactor push button switch.
CAUTION
e. Failed Power Delivery (See Fig. 1)
CAUTION
If the indicating light should go out as soon as the push button switch is released, and the no fault
lights are ON, it indicates that 28.5-V DC holding current is not being supplied from the aircraft to the
plug-interlock relay. Correct the condition and again operate load contactor control push button
switch (22 or 24).
The regulated/diagnostic switch (29) must be set to REGULATED for power delivery. This switch is
located inside the control box behind the control panel.
The No. 1 and/or No. 2 output switch (30 or 31) must be set to AIRCRAFT position. These switches
are located inside the control box behind the control panel.
See section 2-4 for other No. 1 and/or No. 2 Load Contactor Operating Circuit troubleshooting
procedures.
f. Discontinue Power Delivery with Unit Shutdown (See Fig. 1)

(1) Normal conditions

a. Push the load contactor push button switch (22 or 24) to open the contactor. The indicating
light (yellow or orange depending on the contactor used) on that switch will go OFF
immediately to indicate that the load contactor has opened and power is no longer being
delivered to the aircraft. The engine will remain at rated speed.
b. Push the red engine stop push-button switch (20) once to bring the engine down to idle
speed. This will begin the automatic shutdown sequence to shut off the engine, gauges,
lights, etc., after approximately 3 - 5 minutes.
c. Disconnect output cable from aircraft after engine is at idle speed only.

(2) Emergency conditions

a. Depress the EMERGENCY STOP BUTTON (sect. 1-1; 4, fig.1) located on the left front side
of the generator set canopy. When pushed, this button instantly shuts the generator set off
and must be pulled back to reset itself for restarting the generator set.
November 27, 1997
NEVER disconnect the output cable while power is being delivered. Output
contactors must be open prior to removal of the cable from the aircraft.
The generator set must be shut down so that the failed power delivery problems
can be diagnosed. Only licensed technicians should work on this generator set.
Chapter 1-3
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