the DC power system. Both inverters are rated at 750
volt-amperes and provide single phase output only.
Each inverter provides 115 volts, 26 volts, and 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
CAUTION annunciators, and the illumination of the # 1
INVERTER and/or # 2 INVERTER caution annunciator
indicates inverter failure.
Instrument AC annunciator. A red INST
AC warning annunciator, will illuminate if all instrument
AC buses fail.
Inverter control switches. Two switches,
placarded 1f INVERTER # 1 and # 2 on the overhead
control panel (fig. 2-15), control the single-phase AC
frequency meters (fig. 2-15) are mounted on the
continuous monitoring of voltage and frequency on each
115 VA. bus. Normal bus conditions will be indicated by
a reading of 115 VA. and 400 Hz on each meter.
Three Phase AC Power Supply. Three phase
AC electrical power (fig. 2-33) for operation of the
inertial navigation system and mission avionics is
supplied by two DC-powered 3000 volt-ampere solid
state three phase inverters.
Three phase inverter control switches.
Two three-position switches, placarded # 1 IN RESET -
ON -OFF and # 2 IN RESET -ON -OFF, located on the
mission control panel (fig. 4-1), control three phase
Three phase volt/frequency meters. Two
digital three-phase volt/frequency meters, mounted on
the mission control panel (fig. 4-1), monitor and display
the voltage and frequency outputs of the three phase
Three phase loadmeters. Two digital
three-phase loadmeters, mounted on the mission control
panel (fig. 4-1), monitor inverter output level.
Three phase AC off annunciator. An
annunciator placarded 3f AC OFF, located on the
mission annunciator panel (fig. 4-1), indicates a problem
with one of the three phase AC power busses.
Three phase AC external power. External
three phase AC power for operation of the inertial
navigation system or mission equipment can be applied
to the aircraft through an external power receptacle
located on the underside of the left wing just outboard of
the engine nacelle (fig. 2-1 and 2-2). The receptacle is
installed inside the wing structure, accessible through a
hinged access panel. The AC electrical system is
automatically isolated from the external power source if
the external power is over or under voltage, over or
under frequency, or has an improper phase sequence.
The annunciator placarded EXT AC PWR ON, located
on the mission annunciator panel (fig. 4-1), indicates
that external AC power is connected to the 3 phase
busses. The EXTERNAL POWER annunciator in the
advisory annunciator panel indicates that an AC GPU
plug is mated to the AC external power receptacle.
External AC power control switch.
The switch placarded EXT PWR -RESET -ON -OFF,
located on the mission control panel (fig. 4-1), controls
application of three phase AC power to the aircraft.