Electrical Flashcards
TRU ESS switch
In off position isolates TRU ESS from ESS Bus three
DC BUS TIE switch
Opens DC TIE contacter and both ESS TIE contacters when in the off position
BATT ONE selector knob
On: Connects batt one to DC ESS Bus one
OFF: supplies power to hot batt bus one only
IDG EICAS Messages
Output always displayed even if zero.
If output is out of range or is invalid digits are then replaced by three amber dashes.
IDG EICAS ICON indications
Green: IDG is available and knob in auto position
White: IDG is available and selecter knob in off position or engine not running.
Amber Dash: invalid information
AC GCU Icon indications
Green: GPU connected and GPU button pushed in
White: GPU connected and button is pushed out.
Amber Dashed: invalid information
Components of AC System
Two IDGs APU One inverter One RAT ONE AC External power unit
IDG Switches
Auto: allows automatic operation of the electrical system.
Off: opens the contacter and isolates the IDG from the perspective AC bus.
Disc: must be held in this position for IDG to disconnect.
APU Switch
Push in, allows automatic operation
Push out, opens and isolates APU from the AC BUS TIE
AC BUS TIES knob
1 or 2 OPEN,,, opens the bus tie contactor segregating the selected side from the other side.
AUTO,,,,, Allows the system operational logic to control the system automatically.
GPU Button
Push in,,,, connects AC GPU to system according to source priority.
Pushed out, isolates GPU from system..
AVAIL,,,, indicates GPU is avail with proper voltage, amps and frequency
IN USE, GPU is powering system.
BATT EICAS ICONS
Green,,,,, Voltage is greater than 18V
White, less than 18 V
Dashed Amber,,,,, invalid information or value is out of range.
Batt icons always displayed
APU START BATT
Batt 2 is isolated to power the APU start bus.
What must be done with GPU push button after each use once APU takes over?
Us the pushed out even if the IN USE light is out. This must be done for the next connection to work.
Inverter
Converts 28 volt DC from the batteries to 115 Volts AC to supply the STANDBY AC BUS when an AC power source is not available.
RAT rating
15 kVA 115 volts AC 400 Hz three-phase
Number and type of batteries
Two nickel cadmium
Number or TRUs
3 transformer re citified units convert AC to DC.
What distributes electrical power?
Four integrated control centers,,,, ICCs and two secondary power distribution assemblies,,,,, SPDAs
Function of constant speed drives?
Convert variable engine speeds into constant generator speed.
Power output of IDG?
40 kila volt amp, 115 volt, 400 hertz three phase
What is a GCU?
Generator control units… They monitor and control the IDGs
What is the fail safe disconnect for IDG?
Input shear shaft and thermal disconnect operation.
What EICAS message is displayed if loss of electrical power and RAT fails to deploy?
BATT DISCHARGING warning message.
Inverter operation
Converts 28 VDC to 115 VAC 400 Hz frequency stabilized single phase when only battery is providing power.
What is the main source of DC power when AC power is being used?
Three TRUs
Location of each TRU?
TRU ONE is in left integrated control center, TRU TWO is in right ICC and number three is in the emergency integrated control center.
TRU input and a output?
115 volts AC, 400 Hz frequency stabilized input converting that to 28VDC 300 AMPs
Location of batteries?
Number one in front eBay and two in aft eBay.
Do the batteries provide power to anything if BATT switches are off?
Yes, hot battery busses one and two.
Locations of ICCs
Left and right are in middle E bay
Emergency is located in forward e bay
Auxiliary ICC is in the aft e bay
What is in each ICC?
AC and DC busses, thermal circuit breakers line replicable modules.
Breakers are remote breakers
EICAS message for tripped remote breakers?
Cyan, REMOTE CB TRIP
What does ICC power?
AC ONE, DC ONE and AC and DC ground services busses.
What line replacement modules are in ICC ONE?
TRU 1
GCU 1
And external power module
Several thermal breakers
Right ICC powers what?
AC and DC busses two
DC ESS BUS2
What replaceable modules are in right ICC?
TRU 2
GCU 2
Auxiliary GCU
Several breakers
Location of DC ESS bus2?
Right ICC TO PROVIDE DC ESS loads in case of damage to forward e bay.
What is in EMERGENCY ICC
.
AC ESS busses one and three Hot batt bus one Line r mods are TRU ESS Several breakers
Aux ICC provides power and protection to what?
Start bus
Hot bat bus two
Also has several breakers
What are secondary power distribution assemblies and how many?
Two… Manage electrical power and distribute that power based on login and aircraft configuration … Power provided by ICCs
Location of SPDAs
One in front e bay and number two in mid e bay
Can SPDA remote breakers be reset from flight deck?
Yes, through the MDCU
Type of breakers in SPDA?
Electronic and can be reset during flight
What do IDG one and two power?
One powers AC bus one and two powers AC bus two and AC ESS bus
Electrical logic
Onside
APU
GPU, if on ground
Opposite side IDG
Does RAT power full system?
No, just the ESS busses which are AC ESS which powers AC standby as well as TRU ESS. Then TRU ESS powers DC ESS one two and three
What are tie busses
If either IDG fails the tie busses tie that side with the other side allowing full system to be powered.
Types of ground power and functions
AC and DC. AC provide full power to aircraft on ground.
DC can be used to start APU
AC outlet is on front left and DC on aft left
Messages if brake released and hooked to GPU?
GPU connected caution message
