Electrical Flashcards
(55 cards)
What types of components
generally use AC power?
Aircraft components incorporating some type of
movement or motor function (e.g., motors, heaters, and
chargers).
Ref: AOM 2A
What types of components
generally use DC power?
Normally used for control functions or steady-state
operations.
Ref: AOM 2A
How many TRU’s convert AC to
DC power?
Five (5)
Ref: AOM 2A
What’s the difference between red
and black circuit breakers?
Red CB’s are related to essential circuits and black CB’s
are considered non-essential
Ref: AOM 2A
What’s the rating of IDG’s?
They’re rated at 40 kVA and provide three-phase, 400
Hz, 115 VAC power
Ref: AOM 2A
How can a GCU be reset?
By cycling associated generator control switch (L GEN,
R GEN or APU GEN) to OFF and then ON. This action
causes the software to re-initialize.
Ref: AOM 2A
Describe the APU generator
It’s mounted on APU, is usable on ground, or in flight
and produces 3-phase, 400 Hz, 115V AC power. It’s
physically and distinctly different from IDG’s but
produces the same type of power.
Ref: AOM 2A
What’s the purpose of GCU’s?
They work with aircraft electrical system to provide
“quality power”
Ref: AOM 2A
True/False: All non-failure AC
power transfers are NBPT’s,
except between external AC power
and APU power sources.
True
Ref: AOM 2A
Would transfer of power between
the APU generator and external
AC power be a break or no-break
power transfer?
APU generator and external AC power are not frequency
controlled by GCU and BPCU; therefore, power transfer
between these two sources are, break power transfers and,
result in momentary power loss during transfer.
Ref: AOM 2A
How is electrical power normally
controlled?
By two (2) BPCU’s and three (3) GCU’s. BPCU’s are the brains of the system and control most of the contactors. Ref: AOM 2A
What causes “AC” legend of
AC/DC RESET switchlight to
activate?
Fault in Main AC or Emergency AC bus, logic fault
within BPCU, or by relay or component failure
Ref: AOM 2A
What happens when you depress
RESET switch?
It resets lockout and allows tripped contactors to close if
the fault no longer exists
Ref: AOM 2A
When would you select L/R Bus
Tie to ISLN?
When directed by checklist. It prevents the associated
contactor from closing and isolates respective main AC
bus from other power sources.
Ref: AOM 2A
If both AC and DC external power
is connected, which has priority?
External AC
Ref: AOM 2A
Describe RAT deployment.
It’s totally manual and is accomplished by pulling the
guarded RAT DEPLOY handle.
Ref: AOM 2A
What’s the rating of the RAT?
15 kVA
Ref: AOM 2A
What does the RAT power once it
reaches operating speed (usually
5-8 seconds)?
FCC UPS bus and EBHA bus through Emerg AC bus,
and both Essential DC buses through Left and Right
ESS TRU’s
Ref: AOM 2A
How is the RAT stowed?
On ground using an installed hand-operated piston
pump that is mounted above RAT assembly: it cannot
be stowed in flight.
Ref: AOM 2A
What happens as airspeed falls
below the limit of RAT operation
(180 knots)?
RAT stops operating and Main, UPS and EBHA
batteries begin to power flight critical systems for up to
16 minutes
Ref: AOM 2A
What’s the source of power for
personal electronic devices,
electric razors, hair dryers,
blender, toaster, etc.?
50 or 60 Hz power system comprised of two converters.
One converter is active while the other operates in
standby. New architecture has converters operating in
parallel for more power: if one fails, it reverts to single
converter operation.
Ref: AOM 2A
True/False: CABIN / GALLEY
and 60 HZ Master switches are
wired in series (i.e., both must be
selected ON for converters to
produce power).
True. CABIN / GALLEY Master switch also controls
28 VDC to cabin. It’s a single switch for load shedding
all power to cabin.
Ref: AOM 2A
When are L and R AUX DC buses
load shed?
During single generator operation, Aux TRU is not
powered, or when Aux TRU is powering another DC
bus. Load shed feature is inhibited on ground.
Ref: AOM 2A
Describe the purpose of fifth or
Aux TRU.
It serves as backup to primary TRU’s. When not serving
in backup role, Aux TRU powers Left and Right Aux
DC buses which provide 28 VDC power to cabin loads.
Ref: AOM 2A
