Electrical 175 Flashcards
How many networks make up the electrical system on the airplane? Why?
2 independent networks
redundancy and fault isolation
what happens if a power generating source fails?
bus ties automatically connect to provide no systems
what components power the AC system?
2 integrated drive generators (IDGs) (40kVa, 115 VAC, 400 Hz)
Auxiliary power unit (APU)
Inverter (250VA - 28V DC to 115 VAC)
Ram Air Turbine (RAT 15kVA, 115 VAC, 400 Hz)
AC GPU receptacle
What powers the IDG?
respective AC BUS
What is Batt 2’s primary purpose?
Start APU
What is the minimum battery temperature for APU start?
-20 degrees C
What happens when you hit the GPU AVALi button?
it turns from Aval to In Use.
The AC GPU has priority over the batteries to power the electrical system
Correct frequency, amperage, voltage
When does GPU available button turn on?
External GPU cart is properly plugged in
Proper amperage, voltage, frequency
What’s the AC priority
Onside (IDG)
Inside (APU)
Outside (GPU)
Cross side (IDG)
How does ground service and maintenance get power for mx and flight preparation?
Pushing the respective button located on the front ramp panel or on the flight attendant panel at forward right galley
what is the purpose of the inverter? What bus is it connected to ?
converts 28VDC from batteries to 115 VAC to supply the standby AC bus when an AC power source is not available
When does the RAT automatically come online?
Whenever AC power sources are not powering AC buses.
What are the batteries powering during the 8 seconds of RAT deployment?
DC Ess Buses and Standby AC bus
Which pump for RAT drive and what does it do?
AC motor driven pump 3A for primary flight control tasks. high lift system actuation and power for essential avionics, communication and battery recharging.
What is the min speed for RAT? What does the RAT power?
130 kts
DC essential bus 1, 2, 3
AC essential bus
AC standby bus
Hot bat bus 1
Hot bat bus 2
What components power the DC system?
2 NiCad batteries (24 volt, 22 to start)
3 Transformer Rectifier Units (TRU) (rated at 300A, convert 115 AC to 28VDC)
DC GPU receptacle
What is the purpose of the DC GPU?
to start the APU if batteries are below 22 V and temperature is below 20 degrees C.
How many TRUs? Do they rely on each other or isolated?
3 and in isolation. Buses will automatically be powered by the remaining TRUs as long as the DC BUS TIES toggle switch is selected to AUTO
What does TRU 1 power?
provides DC power to DC BUS 1, DC Ess Bus 1, DC GND SVC Bus, HOT bat bus 1 and battery 1 charging
What does TRU 2 power?
provides DC power to DC BUS 2, DC ESS BUS 2, HOT BATT BUS 2 and battery #2 charging
What does TRU Ess power?
DC power to DC ESS BUS 3
what charges the batteries?
any AC source thru the TRUs, including the RAT and AC GPU.
How long do batteries last in an emergency?
10 min
How does IDG maintain a stable power output
a constant speed drive (CDS) attaches the IDG to the AGB (Accessory gear box)
what monitors and controls IDGs
each has a generator control unit (GCU)
What causes the amber IDG light on the overhead panel to illuminate?
High oil temperature
Low oil pressure
What is the primary purpose of the AC generators?
power the AC buses, AC essential bus which powers the 3 TRU (1,2, essential)
whats the minimum battery voltage to close the battery bus ties?
18 volts
what battery is used for APU start?
battery 2
what is the purpose of the inverter?
converts 28 VDC from the 115 VAC to power the AC standby bus when AC source is not available
What is on the AC standby bus?
engine exciters 1A and 2A
When is the RAT icon displayed on the electrical synoptic page
when the RAT is deployed
What manages the electrical system?
4 integrated control centers (ICC)
Left ICC
Right ICC
Emergency ICC
Auxiliary ICC
What is an ICC?
an electrical control device which provides power distribution and protection for electrical loads.
what is SPDA?
secondary power distribution assembly. an electrical load-management unit, powered by ICC, that distributes electrical loads to aircraft systems according to distribution logic and performs BITs (built in tests) on many components
Can the flight crew reset the ICC and SPDA remote electronic CBs?
ICC CB’s can only be reset by maintenance. SPDAs can be reset by crew in MCDU
What are LRU’s and LRMs
LRUs and LRMs allow quick access and easy replacement of electrical components. plug and play. take a module out and put a new one in with new system logic.
What’s on the AC essential bus?
flaps/slats
hydraulic pump 3A
Ac fuel pump 2A
Whats on DC hot bat bus 1?
Courtesy/service lights
ceiling lights
engine 1 oil level indication
engine 1A/2A fire extinguishing
engine fuel SOV 1
Hyd SOV 1
What’s on DC hot bat bus 2?
CMC
Engine 1B/2B fire extinguisher
engine fuel sov 2
hyd system sov 2
panel refuel 3
water and waste system
What turns on when you put Batt 1 on, Batt 2 AUTO?
what’s on AC standby Bus?
engine 1 exciter 1A
engine 2 exciter 2A
What is shed first when we load shed?
galleys and right windshield heating
