Electronics Flashcards

1
Q

What is a pair of unbalanced AC electrical power generators?

A

Circulating currents

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2
Q

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

A voltage regulator

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3
Q

What is the purpose of a CSD (constant speed drive)

A

A CSD is a variable hydraulic pump and motor, connected together so that regardless of engine speed the output will be constant

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4
Q

What is the required output of an alternator?

A

400 Hz

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5
Q

What does an IDG consist of?

A

A CSD and an Alternator

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6
Q

For what reason is there a CSD disconnect mechanism provided?

A

If there was an alternator or CSD failure the pilot may disconnect the input shaft from the drive to prevent any damage

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7
Q

Is IDG disconnection reversible in flight?

A

No, it can only be reconnected on the ground with engines shut down to avoid damage to the drive shaft clutch device.

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8
Q

What is fitted to the aircraft for IDG reconnection?

A

A mechanical reset handle

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9
Q

The IDG converts varying engine accessory gearbox speeds of 4500 - 9125 rpm to a constant generator speed of?

A

12000 +- 120 RPM and 400 +- 4 Hz

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10
Q

What is the voltage and power output of an IDG?

A

115/200 VAC, 90 KVA

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11
Q

What is the IDG oil used for?

A

IDG cooling

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12
Q

When is the emergency power system provided?

A

When the normal power generation fails

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13
Q

What are 2 ways that the emergency generator can be driven?

A

Air driven or Constant speed motor/generator driven

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14
Q

How does an emergency air driven generator work?

A

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)

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15
Q

How does a constant speed motor/generator work?

A

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)

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16
Q

In a TRU why are there 6 diodes connected in parallel in each of the rectifiers?

A

To reduce overheating and produce a steady current output

17
Q

What is the output of a TRU?

A

28vdc, 100 - 200 Amps

18
Q

What does a TRU contain?

A

A primary transformer and 2 secondary transformers that are linked to 2 rectifiers.

19
Q

What is the purpose of a static inverter?

A

Transforms 14 or 28v DC to 400Hz AC

20
Q

What is the aircraft batteries voltage and capacity?

A

24-28Vdc and 20 - 50Ah

21
Q

What is differential current protection?

A

It protects the damage of the electrical wiring and the generator windings between the two detection current transformers

22
Q

Name two types of power distribution systems?

A

Split-Bus system and Parallel Power system

23
Q

Explain a split bus system?

A

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.

24
Q

Explain a Parallel power system?

A

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

25
Q

Under which condition can generators be paralleled?

A

Terminal voltages must be equal, frequencies must be equal and output voltages must be in phase.

26
Q

How is the aircraft structure used in electricity?

A

It is used as the return path or ground

27
Q

What are the three main types of fuses?

A

Glass Tubular, Slow Blow fuse and Current Limiters (current limiters only used by maintenance personnel)

28
Q

What are the two types of circuit breakers?

A

Heat operated and magnetic operated

29
Q

Explain Induced current protection?

A

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.

30
Q

What is the voltage of a lead acid cell?

A

2.1v

31
Q

What is the electrolyte in a lead acid battery?

A

Sulphuric acid and Water

32
Q

How is a lead acid battery charged?

A

Using the constant current or constant voltage method

33
Q

What is an advantage of a Ni-Cad battery or Lead Acid?

A

They can furnish high rates of current without the voltage drop

34
Q

What are the plates in a NiCad battery?

A

Positive - Nickel Hydroxide and Negative - cadmium Hydroxide separated by a thin piece of plastic

35
Q

What is the solution in a NiCad battery?

A

Potassium Hydroxide and water

36
Q

What is the voltage of a NiCad cell?

A

1.25v

37
Q

What is the TRU protected against?

A

Overheating via overheat switches and overcurrent or below a certain minimum current will open the TRU contactor