Hobart 6921 Series Operation And Maintenance Manual page 110

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets
Generator and Excitation Circuit (cont.)
Trouble, Symptom & Condition
No (or low) generator output
voltage in all phases.
Generator operating at 400 Hz
in AUTOMATIC mode.
(Continued)
Chapter 3-1
Page 18
Test or Inspection
f. Defective ballast resistor(s),
(See Fig. 5).
g. Defective Amphenol
connector at voltage
regulator, or defective
wiring from regulator to
exciter field.
h. Defective voltage regulator.
Corrective Action
If output voltage was produced
when the generator set was
operated in MANUAL mode, the
resistors are good. If no voltage
was produced in MANUAL
mode, resistors could be
defective. Refer to Fig. 5 and
connect a jumper lead across
the ballast resistors. If an output
voltage is now produced,
replace resistor(s) as required.
Disconnect voltage regulator
Amphenol connector (see 1-1;
Fig. 12). Using jumper leads
with clip and prod terminals,
connect ungrounded 12-V DC
to terminals "E" and "C" in loose
plug. Connect NEGATIVE to
terminal "E". Connect
POSITIVE lead to "C" terminal
(See Fig. 6).
If the generator will NOT
produce a normal voltage,
replace or repair Amphenol
connector and wiring between
voltage regulator and exciter
field as required.
All components in the excitation
circuit except the voltage
regulator have been tested in
steps (1) through (4) above.
This leaves only the regulator
as a cause of trouble. Replace
complete voltage regulator if the
magnetic amplifier regulator
430391C is used. If solid state
amplifier 489812A is used,
replace PC board.
February 28/94 Revised