Electrical Flashcards
The AC system is composed of:
- two integrated drive generators (IDGs)
- one auxiliary power unit generator (APU)
- one inverter
- one Ram Air Turbine (RAT)
- one AC external power unit
The DC system is composed of:
- two NiCad batteries
- three transformer rectifier units (TRUs)
- one DC external power input
IDG 1 or 2 Selector Knob AUTO
allows automatic operation of the electrical system; closes IDG contactor connecting IDG to the respective AC BUS
IDG 1 or 2 Selector Knob OFF
opens IDG contactor isolating the IDG from the respective AC BUS
IDG 1 or 2 Selector Knob DISC
must be held for one second to mechanically disconnect the IDG.
APU Generator Button PUSH IN/OUT
IN - allows auto operation by connecting APU generator to the AC BUS TIE according to source priority
OUT - opens the APU generator contact
AC BUS TIES Selector Knob 1 OPEN/AUTO/2 OPEN
1 OPEN - opens the Bus Tie Contactor 1, segregating AC BUS 1 from AC BUS 2
AUTO - allows auto operation according to system logic
2 OPEN - opens the Bus Tie Contactor 2, segregating AC BUS 2 from AC BUS 1
GROUND POWER UNIT Button PUSH IN/OUT
IN - connects the AC GPU to the AC BUS TIE according to source priority
OUT - isolates the AC GPU from the AC BUS TIE
TRU Toggle Switches AUTO/OFF
AUTO - allows auto operation by connecting the TRU to their respective DC Bus
OFF - isolates the TRU from their respective DC Bus
BATT 2 Selector Knob AUTO/OFF
AUTO - allows auto operation by connecting battery 2 to the DC ESS BUS 2
OFF - the battery supplies power only to the HOT BATT BUS 2
DC BUS TIE Toggle Switch AUTO/OFF
AUTO - allows auto operation by controlling the operation of the DC Tie Contactors according to system logic
OFF - opens all tie contactors
BATT 1 Selector Knob ON/OFF
ON - the battery is connected to the DC ESS BUS 1
OFF - the battery supplies power only to the HOT BATT BUS 1
IDG and APU gen rating
115 VAC, 40 KVA, 400 HZ, three-phase
Can you reconnect an IDG after manual disconnection
NO
Describe the inverter
the AC/DC inverter converts 28 volt DC power from batteries to 115 volt AC power to supply the STANDBY AC BUS when an AC power source is not available
Ram Air Turbine rating
115 V, 15 KVA, 400 Hz, three-phase AC
When is the RAT automatically deployed
when the AC ESS BUS loses power
What buses does the RAT power after deployment
AC ESS BUS; DC ESS BUSES are powered through the ESS TRU
What hydraulic system does the RAT power after deployment
AC motor driven hydraulic pump (ACMP 3A) from primary flight control tasks
Min speed for RAT to power AC/DC ESS BUSES
130 knots
What will a DC GPU provide power for
APU START BUS
TRUs are rated at
300 A; convert 115 VAC into 28 VDC
TRU 1 provides power to
- DC BUS 1
- DC ESS BUS 1
- DC GND SVC BUS
- HOTT BATT BUS 1
- Batt 1 charging
TRU 2 provides power to
- DC BUS 2
- DC ESS BUS 2
- HOT BATT BUS 2
- Batt 2 charging
TRU ESS provides power to
- DC ESS BUS 3
Battery rating
NiCad 24 VDC, 27A
How are batteries charged
any AC source through the TRUs including the GPU and RAT
Battery power will last how long in an emergency with RAT not fully deployed or RAT stalled
10 minutes
Minimum temperature for Batt 2 for APU start
-20ºC
What provides power for APU start with DC GPU connected
DC GPU and not Batt 2
When is the DC GPU used
when batt 2 is not available or temp is below -20ºC
What is an ICC
Integrated Control Center is an electrical-electronic integrated device providing power distribution and protection for the airplane electrical loads, the secondary power distribution assemblies (SPDAs) and the circuit breakers that are located on the cockpit sidewall panels
Name the four ICCs and their locations
- left integrated control center (LICC) in Center E-BAY
- right integrated control center (RICC) in Center E-BAY
- emergency integrated control center (EICC) in FWD E-BAY
- auxiliary integrated control center (AICC) in AFT E-BAY
What is an SPDA
Secondary Power Distribution Assemblies - electrical load management unit that received power from the ICC AC/DC electrical buses and distributes it to the airplane systems
Where is SPDA 1 located
FWD E-BAY
Where is SPDA 2 located
Center E-BAY
Which remote CBs can the flight crew reset?
SPDA; ICC must be reset by Mx on ground
Electric source priority
- Respective IDG
- APU Gen
- GPU
- Opposite IDG
BATT 1 or 2 OVERTEMP warning
associated battery temperature is above 70C
BATT DISCHARGING warning
batteries are discharging in an electrical emergency with no RAT assistance, or on the ground when the battery is the only power source supplying the airplane
ELEC EMERGENCY warning
in flight, AC main buses are de-energized
GPU CONNECTED caution
AC or DC GPU connected and parking brake released
IDG 1 or 2 OIL caution
high oil temp or low oil pressure; QRH will lead to disconnect IDG
REMOTE CB TRIP advisory
remote thermal or electronic CB has been tripped
What items are connected to DC HOT BATT BUS 1?
Batt 1 Courtesy/Service lights FWD DC Ceiling Lights Engine 1 Oil level indication (in engine oil panel) Engine 1A fire extinguisher Engine 2A fire extingusher Engine 1 Fuel SOV Hydraulic 1 SOV
What items are connected to DC HOT BATT BUS 2?
Batt 2 CMC Engine 1B Fire Extinguisher Engine 2B Fire Extinguisher Engine 2 Fuel SOV Hydraulic 2 SOV Refueling Panel Water/Waste system Controls
