Electrical Power Supply And Distribution System - Beechcraft C-12C Operator And Technical Reference Manual

OFF position. In the OFF position, the blower will not
operate.
(3) The aft vent blower is controlled by a
switch, placarded AFT VENT BLOWER / OFF / AUTO
/ ON. The single speed blower operates automatically
through the CABIN TEMP mode selector when the
Section IX. ELECTRICAL POWER SUPPLY AND DISTRIBUTION SYSTEM
2-81. DESCRIPTION C D1
The aircraft employ both direct current (dc) and
alternating current (ac) electrical power.
electrical supply forms the basic power system
energizing most aircraft circuits. Electrical power is
used to start the engines, to power the landing gear
and flap motors, and to operate the standby fuel pump,
ventilation blower, lights and electronic equipment.
Two inverters operating from dc power produce the
required single-phase ac power. The three sources of
dc power consist of one 20-cell 34-ampere hour
battery and two 250-ampere starter-generators. DC
power may be applied to the aircraft through an
external power receptacle on the right nacelle. The
starter generators are controlled by generator control
units. The output of each generator passes through a
cable to the respective generator bus.
Figures 2-27 and Table 2-7. Other buses distribute
power to aircraft dc loads, and derive power from the
generator buses. The generators are paralleled to
balance the dc loads between the two units. When
one of the generating systems is not on-line, and no
fault exists, aircraft dc power requirements continue to
be supplied, from the other generating source. Most
dc distribution buses are connected to both generator
buses but have isolation diodes to prevent power
crossfeed between the generating systems, when
connection between the generator buses is lost. Thus,
when either generator is lost because of a ground
fault, the operating generator will supply power for all
aircraft dc loads except those receiving power from the
inoperative generator's bus that cannot be crossed.
When a generator is not operating, reverse current
and over-voltage protection is automatically provided.
.
The dc
Refer to
AFT VENT BLOWER switch is placed in the AUTO
position with the landing gear extended. The blower
will automatically shut off when the landing gear is
retracted. The blower operates continuously when the
switch is placed in the ON position and there is a cool
command. In the OFF position, the blower will not
operate.
2-82. DESCRIPTION D2 T
The aircraft employ both dc and ac electrical
power. The dc electrical supply forms the basic power
system, energizing most aircraft circuits.
power is used to start the engines; power the landing
gear pump motor; power the flap motors; operate the
standby fuel pump; power the ventilation blower, lights
and electronic equipment.
operating from dc power produce the required single-
phase ac power. The three sources of dc power
consist of one 20 cell 34-ampere hour battery and two
250-ampere starter-generators.
applied to the aircraft through an external power
receptacle on the right nacelle. The starter generators
are controlled by generator control units. The output
of each generator passes through a cable to the
respective generator bus.
Sheets 1 and 2, and Tables 2-8, 2-9, and 2-10. Other
buses distribute power to aircraft dc loads, and derive
power from the generator buses. The generators are
paralleled to balance the dc loads between the two
units. When one of the generating systems is not on-
line, and no fault exists, aircraft dc power requirements
continue to be supplied, from the other generating
source. Most dc distribution buses are connected to
both generator buses but have isolation diodes to
prevent power crossfeed between the generating
systems, when connection between the generator
buses is lost. Thus, when either generator is lost
because of a ground fault, the operating generator will
supply power for all aircraft dc loads except those
receiving power from the inoperative generator's bus
that cannot be crossfed.
operating, reverse current and over-voltage protection
is automatically provided.
TM 1-1510-218-10
.
Electrical
Two 750-VA inverters
DC power may be
Refer to Figure 2-28,
When a generator is not
2-93