P-9-TM-457-35
T.O. 35C2-3-442-2
TM-07464A-35
TM 5-6115-457-34
Section IX. TACTICAL RELAY BOX
percent for 400 hertz sets. For 50/60 hertz
6-161.
GENERAL.
sets this current rating pertains to the 60
hertz rating. When the above fault occurs,
The tactical relay box (A29) is used
the short circuit relay will actuate. Upon
on both 50/60 and 400 hertz generator sets.
actuation, contacts within the short circuit
It contains the over voltage relay, reverse
power relay, short circuit relay, overload
relay; close to signal the fault locator and
relay, and the three current transformer
open to de-energize the load contactor, re-
sulting in display of the fault condition and
load resistors. Refer to schematic
removal of the load from the generator.
diagram figure 1-18.
a . The over voltage relay (K2) is a solid
d. The overload relay (K14) is a solid
state device which functions to protect the
state device whose function is to protect the
load in the event that generator voltage ex-
load in the event of an overload condition.
ceeds preset limits. It actuates after a time
An overload condition is defined as the state
delay from 180 to 800 milliseconds when gen-
when generator output current in any phase
erator voltage rises above 156 VAC (both
exceeds 110 percent of rated value. The
50/60 and 400 hertz sets). Upon actuation,
overload relay is a current sensing device
contacts within the over voltage relay, close
and operates on an inverse time principle as
to signal the fault locator and open to shut-
the current in any phase exceeds the over-
down the generator set.
load state. At the point just above 130 per-
cent of rated current the overload relay will
b. The reverse power relay (K15) is a
actuate within 8 2 minutes. For 50/60
solid state device which functions to protect
hertz sets this current rating pertains to the
the generator in the event of a reverse power
60 hertz rating. Upon actuation, contacts
operating state during parallel operation. It
within the overload relay; close to signal the
operates in conjunction with the load measure-
fault locator and open to de-energize the load
ment unit which produces a dc output voltage
contactor, resulting in display of the fault
whose polarity and magnitude is a function of
condition and removal of the load from the
the total load on the generator set, regard-
generator.
less of phase or power factor. When the re-
verse power flow into the generator exceeds
6-162.
OVER VOLTAGE RELAY (K2).
twenty percent of rated load; the load meas-
6-163.
ON EQUIPMENT TEST.
urement unit output has sufficient magnitude
and correct polarity to cause the reverse
a. Symptom and Isolation of Malfunction.
power relay to actuate. For 50/60 hertz sets
A malfunction of the overvoltage relay K2 is
this reverse power rating pertains to the 60
usually indicated by failure of the generator
hertz rating. Upon actuation, contacts with
fault monitoring system to detect and react
the reverse power relay; close to signal the
to a voltage rise beyond preset limits. To
fault locator and open to de-energize the load
isolate the malfunction, proceed as follows:
contactor, result in display of the fault con-
dition and removal of the load from the
generator.
WARNING
c. The short circuit relay (K13) is a
Exercise extreme care not to touch
solid state device which functions to protect
exposed electrical connections when
the load in the event generator output current
working inside tactical relay box
in any phase exceeds 425 25 percent of
with generator set operating.
rated current for 50/60 hertz sets and 180
6-126
Change 3
