T.O. 35 C2-3-442-2
P-9-TM-457-35
TM 5-6115-457-34
TM-07464A-35
6-105. DC RELAY ASSEMBLY (A5).
tween the load contactor switch S3 and the
load contactor relay coil CB2, it will allow
Refer to paragraph 6-86 through
or prevent the contactor from being ener-
6-94 for dc relay assembly (A5) maintenance
gized. When this generator set is perfectly
instructions.
synchronized with the other sets, the volt-
age across the synchronizing lights will be
6-106. 400 HERTZ UNDER FREQUENCY
minimum (less than 7 VAC). This causes
RELAY (K12).
the permissive paralleling relay to close its
contacts and allow the generator set to be
6-107. ON EQUIPMENT TEST
paralleled with other generator sets by clos-
ing of its load contactor switch S3. If the
generator set is not perfectly synchronized,
a. Symptom and Isolation of Malfunc-
tion. A malfunction of the underfrequency
the voltage across the synchronizing lights
will be above 9 VAC. This causes the per-
relay K12 is usually indicated by the illu-
mination of the UNDERFREQUENCY fault
missive paralleling relay to have its con-
light or by failure of the load contactor to
tacts open and prevents the load contactor
close with the generator output frequency
CB2 from closing.
normal. To isolate the malfunction, pro-
e. The electronic components assembly
ceed as follows:
(A6) consists of Cl, R4, and R5. The as-
sembly connects to the `governor control
WARNING
unit and acts as a feedback circuit to provide
the governor with greater frequency stablil-
Exercise extreme care not to touch
zation.
exposed electrical connections when
working inside mode II relay box
with generator set operating.
f. The variable resistor (R29) is a
potentiometer which permits adjustment of
the reactive KVA between sets operating in
NOTE
parallel. Its slotted shaft, when rotated
Remove cover from mode II relay
clockwise, will cause the corresponding
set to increase its share of the total reactive
box to gain access to the test points,
KVA .
see figures 6-15 and 6-22.
g. The governor paralleling control is
1. With the generator set operat-
a rheostat (R28) which permits initial
ing at rated speed and voltage, measure
matching of the governor paralleling cir-
the voltage from terminal 1 to terminal
cuits for sets operating in parallel. Its
2 of the K12 relay. The nominal voltage
function is to ensure proper real load
is 120 VAC.
sharing. It has a slotted shaft with locking
device which when rotated counterclockwise
2. If the voltage at terminals 1
will cause an increase in signal appearing
and 2 is normal and fault light is still
at paralleling receptacles, causing the gen-
illuminated, remove the wire from ter-
erator to assume a greater share of the
minal 6 of K12 relay and reset fault lamp.
load.
If fault lamp can be reset, relay K12 is
defective.
Change 3
6-83
