MULTIQUIP DCA Series Service And Troubleshooting Manual page 88

LOW VOLTAGE - NO LOAD
Verify Low
Voltage Output
Start unit and run at
1800 RPM. Verify output voltage
at top of circuit breaker with
multimeter. Phase to Phase
and Phase to
Neutral
FAIL
Is engine
speed running
at 1800 rpm?
NO
Adjust or repair
engine.
Is frequency
meter reading
lower than
40 Hz @
1800 rpm.
NO
Test Exciter
Field.
Disconnect 6 pin connector
from CN1 receptacle on AVR.
Measure resistance at pins
J and K on CN5 plug.
Reference Table 6
for correct
resistance
FAIL
Repair wiring or
replace Exciter Field
PAGE 88 — GENERATOR SERVICE AND TROUBLESHOOTING MANUAL — REV. #0 (08/29/23)
TROUBLESHOOTING FLOWCHARTS
Inspect and troubleshoot
PASS
voltmeter on control
panel/digital controller
Is voltage
balanced phase
YES
to phase and
phase to
neutral
YES
Does voltage
adjust with
rheostat?
NO
Loose, damaged
NO
or corroded
connectors
on AVR?
YES
PASS
Test Rotating
Rectifier. Reference
Rotating Rectifier
test section.
FAIL
Replace rotating rectifier.
Reference troubleshooting
NO
voltage unbalanced flowchart.
Voltage adjusts
YES
but is not high enough
Repair or replace
YES
faulty connectors
and retest unit.
Unplug 2-pin
connector on AVR,
measure resistance
0-1000 ohms
as VR knob is
rotated
FAIL
Manual
Excitation Field
Test
Disconnect 6 pin connector
fr om CN1 receptacle on AV R.
Connect 12 VDC battery to pins
J and K on CN5 plug
Reference Table 7
for correct
voltage
FAIL
With Rotating
PASS
Rectifier disconnected
test Exciter
Armature
FAIL
Replace or refurbish rotor
Adjust the coarse
potentiometer
on AVR.
PASS
Rheostat OK
Replace rheostat
and retest voltage.
If AC output voltage
meets values as
PASS
referenced in Table 7
Indicates faulty AVR,
Replace AVR and
retest unit.
With Rotating
PASS
Rectifier disconnected
test Main
Field
FAIL
Replace or refurbish rotor