Generator and Excitation Circuit (cont.)
Trouble, Symptom & Condition
Test or Inspection
Corrective Action
Load contactor (K1) will close
when control switch (20, Fig. 1
is held in momentary CLOSE
position. Opens immediately
when switch is released to
center ON position. (cont.)
d. “Blown” fuse (F2) (1-1; 17,
Fig. 9) in protective relay
tray.
Press lamp test switch (8, Fig.
1). If lamps do not glow, replace
fuse (F2).
e. Defective plug-interlock
relay (K2).
Place test-bank switch (S2) (34,
Fig. 1) in ON position. If load
contactor will now remain
closed, replace the
plug-interlock relay (K2) (Sect.
1-1; 1, Fig. 9) or the complete
protective relay tray.
f. Small contacts in load
contactor (K1) defective.
Connect a jumper lead between
small terminals N.O. and C on
the load contactor. If the load
contactor will now remain
closed, replace the complete
load contactor (K1).
g. Defective fuse interlock
relay (K 17) or resistor
(R46).
Open protective relay tray and
connect a jumper across the
resistor (R46) (Sect. 1-1; 21
Fig. 9). If the contactor will now
remain closed, replace fuse
interlock relay (K17) (Sect. 1-1;
2, Fig 9) or replace the
protective relay tray assembly.
5.
Load contactor opens during
power delivery. NO fault
indicating lights on.
a. Fuse (F1 or F2) blown.
Remove and inspect fuses (1-1;
16 and 17, Fig. 9.) Replace as
required.
b. A fault has developed in the
load contactor holding
circuit.
If the load contactor cannot be
closed by operation of the
control switch (S5) (20, Fig. 1),
check the circuit in accordance
with instructions 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. Cable accidentally
disconnected from aircraft.
Reconnect cable.
OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets
February 28/94 Revised
Chapter 3-1
Page 21
Summary of Contents for 6921 Series
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