Electrical Flashcards
(41 cards)
What happens if a power generating source fails?
Bus ties automatically connect to provide no system degradation.
What components power the AC system?
2 integrated drive generators (IDG) Auxiliary Power Unit (APU) Inverter Ram Air Turbine (RAT) AC GPU receptacle
What components make up the DC system?
2 NiCad batteries
3 Transformer Rectifier Units (TRU)
DC GPU receptacle
How does the IDG maintain a stable power output?
A constant speed drive attaches the IDG to the Accessory Gear Box
What monitors and controls the IDGs?
Each has a Generator Control Unit (GCU)
Can one IDG supply the entire electrical system?
Yes
What will cause the amber IDG light on the overhead panel to illuminate?
High oil temperature
Low oil pressure
If an IDG is manually disconnected can it be reconnected by the flight crew?
No, it is a maintenance function
What is the primary purpose of the AC generators?
To Power the AC BUSSES and AC ESS BUS which powers the 3 TRUs (1,2, and ESS)
What is the purpose of the TRUs?
To convert 115 VAC to 28 VDC
300 amps
Can the APU replace a failed IDG?
Yes
What is the AC electrical system’s priority?
IDG (onside)
APU (inside)
GPU (outside)
Other IDG (cross-side)
How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?
GPU button displays AVAIL and GPU icon is presented on the electrical synoptic page. Once the GPU button is pushed in, the button will display IN USE provided another AC power source is not available.
What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?
Ground Service bus is in use
Cockpit GPU button will display AVAIL even though the ground service bus is in use
If the airplane is using the AC GPU and APU is started what should the pilot be sure to do?
Deselect the GPU button before the next GPU connection
What will charge the batteries?
Any AC power source
How long will the aircraft’s batteries last with no recharging?
10 minutes
What is the purpose of the DC GPU receptacle?
For APU start when the batteries are less than 22.5 VDC or
If battery temp is less than -20 degrees C.
What is the minimum battery temp for APU start?
-20 degrees C
What is the minimum battery voltage to close the battery bus-tie?
18 volts
What battery is used for the APU start?
BATT 2 powers the APU start Bus
BATT 1 powers the FADEC & EICAS for monitoring
What is the purpose of the inverter?
Converts 28 VDC from the batteries to 115 VAC to power the AC STANDBY BUS when an AC source is not available
What is on the AC STANDBY BUS?
Engine exciters 1A and 2A
What powers the Ram Air Turbine (RAT)?
Airflow turns the RAT propeller which spins the turbine inside
