Electrics Flashcards
How many volts of AC does the aircraft use, and from what sources?
115 VAC:
Two variable frequency generators(VFG’s) provide primary power
An APU VFG provides auxiliary power
A ram air turbine (RAT) provides a lower rated generator for emergency power
An external connection provides ground power
How many volts DC power and from what sources?
Three transformer rectifier units (TRU’s) provide primary DC power
Two nickel cadmium (NiCad) batteries provide emergency DC power and allow APU startup when external AC power is not available
Two permanent magnet alternator generators (PMAG’s) provide power for the FBW and FADEC
The engine and APU VFG’s are controlled with what in the cockpit.
The L GEN, R GEN, and APU GEN switch/lights on ELEC panel.
How many kVA do any of the three VFG’s produce, where are they located, and how are they cooled?
75 kVA ,and both VFG are located on engine accessory gearbox, APU is located on APU accessory gearbox.
*Engine VFG’s are cooled and lubricated by a self-contained oil system.
The APU VFG….
Mounted on the APU accessory gearbox, provides up to 75 kVA up to FL 365, amperage output gradually decreases at higher altitude.
The Generator Control Units (GCUs). What do they do?
Regulate VFG voltage
Control contactors that connect and disconnect the VFGs to/from the main AC buses
Protect the electrical channels from generator faults
Provide generator status information.
External AC power is located where and function in what two modes?
Located at left forward fuselage.
Two modes:
Ground Service Mode
External Power Mode(connected for correct voltage frequency and phase).
Pressing the EXT PWR SERV(on the electrical service panel)switch/light activates what?
Activates the Ground Service Mode
What does the Ram Air Turbine(RAT) do and how much power does it supply?
- Deploys automatically in flight when AC power is lost
- A 10 kVA inter grated generator supplied emergency AC power to the AC ESS BUS, and DC ESS BUS 3 through TRU 3, at 148 KIAS and above.
Can the RAT be retracted in flight?
No
The batteries are rated @, and what do the batteries automatically supply power to?
There are two 24 VDC(volts DC) NiCad batteries, each rated @ 42 Amp/hour.
Note: Batt automatically provides power for BATT DIR BUSES and DC EMER BUSES
If an engine is not running, or in the event of a Permanent Magnet Alternator Generator(PMAG) failure, each FADEC Ch. receives power from?
DC ESS BUSES
Makes sense when AC is loss
The BATT rotary switches control:
the Bus Powered Control Units (BPCUs) and the battery chargers.
What happens when the OIL light illuminates on the L/R DISC switch for the Variable Frequency Generator?
Low oil pressure or high oil temperature.
If the VFG oil continues to increase beyond high limit threshold, what happens?
The VFG will automatically disconnect from the engine gearbox.
