Flashcards in Electronics Deck (37):
What is a pair of unbalanced AC electrical power generators?
I sense the voltage of all 3 phases in the generator and if they are not equal I will adjust them accordingly, what am I?
A voltage regulator
What is the purpose of a CSD (constant speed drive)
A CSD is a variable hydraulic pump and motor, connected together so that regardless of engine speed the output will be constant
What is the required output of an alternator?
What does an IDG consist of?
A CSD and an Alternator
For what reason is there a CSD disconnect mechanism provided?
If there was an alternator or CSD failure the pilot may disconnect the input shaft from the drive to prevent any damage
Is IDG disconnection reversible in flight?
No, it can only be reconnected on the ground with engines shut down to avoid damage to the drive shaft clutch device.
What is fitted to the aircraft for IDG reconnection?
A mechanical reset handle
The IDG converts varying engine accessory gearbox speeds of 4500 - 9125 rpm to a constant generator speed of?
12000 +- 120 RPM and 400 +- 4 Hz
What is the voltage and power output of an IDG?
115/200 VAC, 90 KVA
What is the IDG oil used for?
When is the emergency power system provided?
When the normal power generation fails
What are 2 ways that the emergency generator can be driven?
Air driven or Constant speed motor/generator driven
How does an emergency air driven generator work?
An ADG is projected into the airstream and drives a shaft directly to the generator. There is a built in governor that adjusts the blade angle for a constant generator speed. (25 KVA)
How does a constant speed motor/generator work?
A RAT drives a shaft at a hydraulic pump, the pump provides hydraulic pressure for the most essential systems and helps drives a motor that drives a generator (5KVA)
In a TRU why are there 6 diodes connected in parallel in each of the rectifiers?
To reduce overheating and produce a steady current output
What is the output of a TRU?
28vdc, 100 - 200 Amps
What does a TRU contain?
A primary transformer and 2 secondary transformers that are linked to 2 rectifiers.
What is the purpose of a static inverter?
Transforms 14 or 28v DC to 400Hz AC
What is the aircraft batteries voltage and capacity?
24-28Vdc and 20 - 50Ah
What is differential current protection?
It protects the damage of the electrical wiring and the generator windings between the two detection current transformers
Name two types of power distribution systems?
Split-Bus system and Parallel Power system
Explain a split bus system?
Generally fro 2 engine aircraft where each engine provides power to its own bus. in the event of generator failure the generator breaker will open and the BTB close.
Explain a Parallel power system?
This is usually for aircraft with 3 engines or more. it works by having all generators connected to a common bus and sharing the loads equally
Under which condition can generators be paralleled?
Terminal voltages must be equal, frequencies must be equal and output voltages must be in phase.
How is the aircraft structure used in electricity?
It is used as the return path or ground
What are the three main types of fuses?
Glass Tubular, Slow Blow fuse and Current Limiters (current limiters only used by maintenance personnel)
What are the two types of circuit breakers?
Heat operated and magnetic operated
Explain Induced current protection?
A reversed bias diode is placed across a coil so when the voltage spikes and travels in the reverse direction it is transferred back through the coil and dissipated.
What is the voltage of a lead acid cell?
What is the electrolyte in a lead acid battery?
Sulphuric acid and Water
How is a lead acid battery charged?
Using the constant current or constant voltage method
What is an advantage of a Ni-Cad battery or Lead Acid?
They can furnish high rates of current without the voltage drop
What are the plates in a NiCad battery?
Positive - Nickel Hydroxide and Negative - cadmium Hydroxide separated by a thin piece of plastic
What is the solution in a NiCad battery?
Potassium Hydroxide and water
What is the voltage of a NiCad cell?