Hobart 60CU24, Operation And Maintenance Manual With Illustrated Parts List, Page: 114 / 234

OM-2098C / Operation and Maintenance Manual
60CU24 / Series 500060C / 400 Hz. Generator Set
April 01, 2005 Chapter 2-4
Page 20
Trouble, Symptom, Condition Probable Cause Test, Check, and/or Remedy
Protective Circuit (continued)
NOTE: Protective monitoring is not completely functional until load contactor is CLOSED. Since it is not
advisable to vary voltages for test purposes while delivering power to an aircraft, the GPU should be
connected to a load bank for trouble shooting protective circuits. To avoid repetition, it will be assumed that
“
TEST/RESET ” push-button switch has been pressed and the load contactor has been closed before
commencing each test.
a. Frequency adjust switch is
enabled.
Set frequency adjust switch to
DISABLE 4. Load contactor opens during
power delivery. Under frequency
fault indicated.
b. Defective REG board. If under-frequency faults continue
after engine’s ECM is proven to be
good, and an under-frequency
condition does not exist, replace
REG board.
a. There may have been an
overload condition.
Observe ammeter. Check for
abnormal overload condition and
correct. If overload device
functions to open load contactor
when an overload does not exist,
proceed to step B. 5. Load contactor opens during
power delivery. Overload fault
indicated.
b. Defective CTL board. Replace CTL board.
Trouble, Symptom, Condition Probable Cause Test, Check, and/or Remedy
Generator
a. Shorted diode in exciter rectifier
(CR2).
Check diodes in accordance with
Section 2-3. If diodes are good,
proceed to step B.
b. Open or shorted exciter rotor
winding (G2)
Use ohmmeter to check for open
or shorted condition diodes in
accordance with Section 2-3. If
exciter rotor windings are good,
proceed to step C.
c. Open or shorted exciter field
windings (L2)
Check field resistance. See
Section 2-3 for normal values.
1. No (or low) voltage output
d. Open or shorted generator
rotor windings (L1)
Check resistance with ohmmeter
to determine if open or short
circuited diodes in accordance
with Section 2-3
2. Generator operates single
phase.
a. Open or short circuited winding
in generator stator (G1)
Check stator-winding resistances.
See Section 2-3 for normal values.
3. Generator overheats a. Loose connection causing high
resistance.
Check all output connections.
Look for discoloration caused by
heat. Tighten or replace as
required.