11.6 Flashcards
what are the electrical voltages mainly used on an aircraft?
28vdc
115/200 VAC 400Hz
Batt 24 VDC
what does the electrical power system consist of?
Generation subsystem
Distribution subsystem
what is used to convert AC to DC from the IDG?
transformer rectifier unit
what are some electrical sources on an aircraft?
IDG
APU
RAT
GPU
what are aircraft batteries used for?
emergency power
APU starter motor power
when are the batteries charged?
during normal operation of the electrical power system
how is dc converted to ac?
a static inverter
what is the dc power source in flight?
IDG (this is AC)
why are the batteries semi-sealed (vented)?
to allow gases to escape but prevent spillage of the electrolyte
are secondary cells rechargeable?
yes
in an emergency how long should the battery supply power for?
30 mins
where are batteries vented to?
overboard/outside non return valve to prevent reverse flow
what is the purpose of a battery tray?
catch split electrolyte
what are the two types of batteries on auto pilot?
ni-cad
lead acid
what voltage are individual cells:
during charging?
during discharge?
charging - 1.5v
discharging - 1.0v when fully discharged
what should battery checks consist of?
storage capability
electrolyte condition
how is the change level checked in a Ni-cad battery?
only possible by monitoring the voltage and current during charging
what batteries are highly susceptible to thermal runaway?
Ni-cad
what are the charging methods?
constant voltage
constant current
what type of battery uses constant current charging?
Ni-cad
what are batteries monitored for?
their temperature
when is the hot battery bus connected to the battery?
always
where would electrical info be displayed?
ECAM/EICAS
when removing and installing a battery what order are loads removed/installed?
Removal
neg first
install
neg last
what are some advantages of lithium over NI-cad?
high v and i production
improved power quality
recharge quick
30% lighter
compact
no memory degradation
a dc generator is required to supply a constant voltage within set limits under what conditions?
full range of engine speeds
no loads up to full load
share load with over gens
what is shown on the generator identity plate?
rotation direction
what is the purpose of the equalising coils?
equalise outputs from the IDG in parallel systems
