P-9-TM-457-35 T.O. 35C2-442-2
TM-07464A-35 TM 5-6115-457-34
Section VII. MODE II RELAY BOX ASSEMBLY
b. The underfrequency relay (K12) is
6-104. GENERAL.
a solid state device which funtions to pro-
tect the load in the event generator fre-
The mode II relay box assembly
quency decreases below preset limits. It
(A27) is a junction box which is utilized to
actuates when generator frequency drops
interconnect certain electronic componentry
below 370 5 hertz. Upon actuation, con-
for 400 hertz precise generators sets. The
tacts within the underfrequency relay close
relay box contains the dc relay assembly,
to signal the fault locator and open to de-
the under frequency relay, under voltage
energize the load contactor, resulting in
relay, permissive paralleling relay, engine
display of fault condition and removal of
crank relay, governor paralleling control,
load from generator.
voltage regulator paralleling control gov-
ernor feedback capacitor, frequency adjust
c. The under voltage relay (K11) is a
device fixed resistors, cross current trans-
solid state device which functions to protect
former and burden resistor, and the battery
the load in the event generator voltage de-
charging ammeter shunt. Refer to schematic
creases below preset limits. It senses
single phase 120 VAC. The time lag be-
tween an under voltage condition and activa-
a. The dc relay assembly (A5) is a
tion of relay switching depends upon the
component mounted printed circuit board.
magnitude of the voltage sensed. When the
It contains the field flash relay K5, figure
input voltage drops below 48 VAC, the de-
1-16, parallel operation voltage sensor
vice shall operate instantaneously. For
rectifier bridge CR4 and relay K7, fuel
voltages above 72 VAC, the device shall
level relay K8, start circuit diode CR3,
fuel pumps diode CR6, and paralleling lights
operate in 6 2 seconds. Upon actuation,
contacts within the under voltage relay,
resisters R6 through R9. Resister R3,
close to signal the fault locator and open to
rectifier bridge CR4, and relay K7 are con-
de-energize the load contactor, resulting
nected in parallel with winding T6-T9 of the
in display of the fault condition and removal
generator assembly. When the generator
of the load from the generator.
output is connected for 120/208 VAC output;
T9 is reconnected to T3 and T6 is connected
d. The permissive paralleling relay
to T12. The voltage across this phase coil
is rectified by CR4 and then applier to relay
(K16) is utilized only on precise generator
sets. Its function is to ensure that a gen-
K7. This causes its contacts to short out
erator set cannot be paralleled with other
resisters R9 and R6 in series with the
generator sets until synchronization is ac-
synchronizing lights DS4 and DS5. When the
generator output voltage is reconnected for
complished. It accomplishes this by sensing
the voltage drop across one of the synchron-
240/416 VAC; terminals T6 and T9 are con-
ization lights. When the voltage exceeds 9
nected together. This de-energized relay
VAC, the relay contacts are open. When
K7, and resistors R6 and R9 are connected
in series with synchronizing lights DS4 and
the voltage is less than 7 VAC, its contacts
DS5.
close. Since its contacts are connected be-
6-82
Change 3
