11.6 Flashcards by Jayden Mcneil

Ac and dc voltages

Ac 115

Dc 28 -> 24

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In a 3 phase system what’s the voltage between each phase

120

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How long is emergency power from the battery for

At least 30m

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What is the battery used for

Emergency power and apu start

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What power source does the EDG provide during flight

Dc power source

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Why do we need vents on batteries

Gas to escape and prevent spillage

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How can you disconnect the battery in an emergency

By hand no need for wire cutters

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Cell voltage when discharged and charging

1v when discharged

1.5v when charging

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How often does maintenance occur on batteries

Every 2000 hours but never performed on aircraft

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Why is it necessary to avoid too many apu starts

Overheat the battery which reduces electrolyte level and melts plastic separator

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What voltage should you not discharge a battery

Under 22v

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What should you monitor on ni cad batteries

The voltage and current during charging

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What battery is constant voltage

Lead acid

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What battery is constant current

Ni cad

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When removing a battery what do you disconnect first and why

Negative lead to prevent shorts

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What is lead acid electrotype topped up with

Distilled water only

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What are the characteristics of lithium ion batteries

8 cells

28dc

75amph

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What’s the advantages of lithium ion batteries

30% lighter

Quicker recharge

No memory degradation

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Lithium ion charging stage

Constant current

Balence

Voltage source

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Source of power for DC

Battery

External

Generators

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How does the generator state the direction of rotation

On the identity plate or an arrow on the stator externally

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What does a tru do

Turn ac into dc voltage at 28v or 14v

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How does the parallel system work

Two or more generators connected to the sync bus

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How does non-parallel work

All the loads are supplied through the bus bar

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What does an equalising coil do

Makes sure the power supplied or consumed by the IDG is equal

What happens if one of the generators fails and bus tie breaker closes

The two bus bars connect with serviceable generator to supply both busbars

What 3 things generate ac current

Ac generators Static inverters Rotory inverters

What phase is ac generation

Three phase 400hz 115/200v

How is generator output controlled in ac

Integrated control and protection unit

What is AC wild

Faster the rotor turns, the higher the frequency

What does a csd do

Adapts variable engine speed into constant

What’s the purpose of fly weights

Keeps output at 400hz

What’s the oil circuit used for

Cooling and lubrication

What does a generator rotor do

Increase or decrease voltage of frequency outlet

What the two temperature indications

Absolute oil temperature and rise in temperature

What is underspeed

Input speed drops below normal control range

What a constant speed drive disconnect

Electrically actuated device that decouples the input shaft from the input spline shaft if futures transmission malfunction

How do you know if the csd disconnection is successful

Voltage and frequency will display 0

How do you operate the disconnect button

Press no longer then 3 seconds Don’t press more then once every 60 seconds

How does the constant speed drive unit work

Concert variable engine rpm to generator speed of 12000 rpm

What type of generator is csdu and what does it output

Brushless 200v at 400hz and also 90kva continuously

What are the 3 gcu functions

Regulation Protection Switching

What is a current transformer

Used as an amp clamp

Is there physical contact between cables and the transformer

How is emergency power generated

Battery and ram air turbine

What bus is the battery connected to

Hot battery bus

What is the essential bus connected to

Anything that will allow the aircraft to fly safe

What is voltage regulation done by

Gcu

How are the poles ordered

Always in pairs

How are poles ordered in DC

2,4,6 poles

What is an inverter

Dc to ac 28vdc becomes 26vac or 115vac

What inverter is better

Static as it quieter and has no moving parts

What does a transformer do

Steps voltage and current up & down Current and voltage work in opposite

What are rectifiers and the 2 types

Change ac to dc Half wave & full wave

What does a tru do

Convert 115vac from engine or apu to 28vdc

What is main power distribution

Electrical power to main consumers

Who is the emergency power distribution for

Consumers that can land aircraft safely

What are fuse and circuit breakers used to do

Prevent currents Higher then the maximum of the cross sectional area

What do you do with a blown fuse

Replace after blown

What do you when a circuit breaker pops

Reset after the circuit fault is removed

How many times can you replace a circuit breaker in flight

Once

Why are circuit breakers used as manual on/off switches

To allow deviation of circuits

What is a short circuit

Hard short between high voltage side to ground or different potential difference

What type of cb is push/pull pop out

Single-pole thermal device

What is the most common circuit breaker

Thermal & magnetic or electromagnetic

What voltage does an external ground power unit supply

115vac and 28vdc

How many pins in dc got

3 pins 2 positive 1 negative

How many pins does an ac gpu have

6 pins 4 larger ones 2 smaller

In an AC gpu what are the 4 pins

Phase A B C & nuetral