Figure 2-27. Overhead Circuit Breaker Panel
The switch is connected to the battery relay circuit and
must be ON when energizing the battery master power
switch. The key cannot be removed from the lock when
in the ON position.
Circuit Breakers. The overhead circuit breaker
panel (fig. 2-27) contains circuit breakers for most
aircraft systems. The circuit breakers on the panel are
grouped into areas which are placarded as to the
general function they protect. A DC power distribution
panel is mounted beneath the floor forward of the main
spar. This panel contains higher current rated circuit
breakers and is not accessible to the flight crew under
2-74. AC POWER SUPPLY.
Single Phase AC Power Supply. AC power for
the aircraft is supplied by inverter units, numbered No.1
and No.2 (fig. 2-24) which obtain operational current
from the DC power system. Both inverters are rated at
750 volt-amperes and provide single-phase output only.
Each inverter provides 115 volt and 26 volt, 400 Hz AC
output. The inverters are protected by circuit breakers
mounted on the DC power distribution panel mounted
beneath the floor. Controls and indicators of the AC
power system are located on the overhead control panel
and on the caution/, advisory annunciator panel.
AC Power WARNING/CAUTION Lights.
Two MASTER CAUTION lights and the illumination of
an annunciator caution light No.1 INVERTER or No.2
INVERTER indicates and inverter failure.
Instrument AC Light. A red warning light,
located on the warning annunciator panel, placarded
INST AC, will illuminate if all instrument AC busses
Inverter Control Switches. Two switches,
placarded INVERTER No.1 and No.2 on the overhead
control panel (fig. 2-12) give the pilot control of the
single-phase AC inverters.
voltfrequency meters (fig. 2-12) are mounted in the
overhead control panel to provide monitoring capability
for both 115 VAC buses. Normal display on the meter is
shown in frequency (Hz). To read voltage, press the
button located in the lower left corner of the meter.
Normal output of the inverters will be indicated by 115
VAC and 400 Hz on the meters.
Three Phase A C Power Supply. Three phase
AC electrical power for operation of the inertial
navigation system and mission avionics is supplied by
either of two DC powered 3000 voltampere solid state
three phase inverters.