Hobart 60PL20 Operation And Maintenance Manual page 95

TROUBLE, SYMPTOM
AND CONDITION
LOAD CONTACTOR OPERATING CIRCUIT (Continued)
3. Load contactor
opens during power
delivery. NO fault
indicating lights on
PROTECTIVE CIRCUIT
NOTE: The protective relays and protective monitor are not completely functional until the load
contactor is CLOSED. Since it is not advisable to vary voltages for test purposes while delivering
power to an aircraft, the generator should be connected to a load bank for trouble shooting the
protective circuits. To avoid repetition, it will be assumed that the reset switch [(6), Fig. 1] has been
pushed and theload contactor has been closed before commencing each test.
1. Load contactor
opens during power
delivery. Over-
voltage indicating
light ON
December 31/91 Revised
PROBABLE CAUSE
B. A fault has devel-
oped in the load
contactor holding
circuit.
C. Cable accidentally
disconnected from
aircraft.
A. The overvoltage con-
dition may have been
the result of a sud-
den drop in the load,
or possible tampering
with voltage regula-
tor potentiometer
(27, Fig. 1), and may
have been a normal
action.
B. Defective over-under-
voltage sensing mod-
ule (K26)
TEST, CHECK, AND/OR
REMEDY
B. If the load contactor cannot
be closed by operation of
the control switch (S5) (20,
Fig. 1), check the circuit
in accordance with instruc-
tions in Trouble 1, above
under LOAD CONTACTOR
OPERATING CIRCUIT. If the
load contactor can be closed, but
opens as soon as control
switch (S5) is released,
check for trouble under
Trouble 2, above.
C. Reconnect cable.
A. Press reset switch (6,
Fig. 1) and resume power
delivery. Observe voltmeter
(2, Fig. 1) to be certain
voltage is normal 115 V AC.
Adjust to normal if necessary. If
the load contactor is opened
again and an over-voltage condi-
tion is indicated by OV indicating
light, proceed to step B.
B. Use voltage adjusting
potentiometer (27, Fig. 1)
to reduce voltage to 110 V
AC. Observe voltmeter and
gradually increase voltage with
potentiometer. If the over-under-
voltage sensing module (K26)
functions to open the load
contactor at any value less than
134 VAC, it is defective. Replace
over-undervoltage module.
OM-2053
3-1
Page 17