Aircraft AC Generation Systems Flashcards
What is the purpose of a constant speed drive (CSD)?
Maintain a constant generator shaft speed under various loads to ensure a constant generator frequency output
Maintain a constant generator shaft speed under various loads to ensure a constant generator voltage output
Maintain a constant generator shaft speed under various loads to ensure a constant current output
Connect the engine or gearbox to the generator control unit
Maintain a constant generator shaft speed under various loads to ensure a constant generator frequency output
Which component in the AC generation system provides cockpit load meter indications?
Autotransformer
Line contactor
Current transformer
PMG
Current transformer
Which function of the GCU protects the AC generator during system shutdown?
Voltage regulation
Feeder fault protection
Reverse-current detection
Improper phase detection
Reverse-current detection
What are the two types of inverters used in aircraft?
Static and non-static
Rotary and auto
Static and rotary
TR and GCU
Static and rotary
What is the purpose of a Constant Speed Drive (CSD) unit?
Regulates generator output voltage
Maintains a consistent generator frequency output
Provides excitation voltage to the main windings
Regulates a constant engine speed during normal operation
Maintains a consistent generator frequency output
What does a discolored autotransformer indicate?
Overheating
Normal wear
Over-frequency
Electrolyte leakage
Overheating
How does a brushless generator induce an exciter field voltage?
A signal from the generator’s exciter diode unit is sent to the voltage regulator.
A signal is sent through the commutator to the rotating field.
A signal from the generator’s permanent magnet is regulated and sent to the exciter coil of the generator.
Brushless generators do not require an exciter field.
A signal from the generator’s permanent magnet is regulated and sent to the exciter coil of the generator.
During flight, the IDG is disconnected due to an over temperature condition. How is the IDG re-connected?
Automatically, when the temperature returns to a normal range
Manually, by the flight crew
The cockpit switch is returned to ON.
The IDG can only be reconnected by maintenance personnel on the ground.
The IDG can only be reconnected by maintenance personnel on the ground.
If the GCU detects an abnormal voltage condition that it cannot correct, the GCU disables the AC generator by _______.
physically disconnecting the AC generator from the engine/gearbox
physically disconnecting the CSD from the engine/gearbox
generating a control voltage that opens the line contactor, which disconnects the generator from the bus
generating a control voltage to the PMG that shuts the generator down
generating a control voltage that opens the line contactor, which disconnects the generator from the bus
What is the typical maintenance process when an autotransformer fails?
Repair the coils of the autotransformer.
Flash the field to reintroduce the magnetic poles.
Remove and replace the autotransformer with a new unit.
Remove, disassemble, overhaul, and replace the autotransformer.
Remove and replace the autotransformer with a new unit.
When a helicopter is in flight, which GCU protection function is disabled?
Over-voltage
Under-voltage
Over-frequency
Under-frequency
Under-frequency
The rotary inverter combines two components to generate AC. They are _______.
AC motor and DC generator
DC motor and full-wave bridge rectifier
step-down transformer and DC generator
DC motor and AC generator
DC motor and AC generator
Line voltage is _______ greater than phase voltage.
equal to
- 5 times
- 73 times
- 5 times
1.73 times
What is the purpose of an instrument autotransformer?
Step down 115 VAC to 26 VAC
Step up 12 VDC to 28 VDC
Charge the aircraft batteries in flight
Step up 26 VAC to 115 VAC
Step down 115 VAC to 26 VAC
