Electrical Flashcards

1
Q

What happens if a power generating source fails?

A

Bus ties automatically connect to provide no system degradation.

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2
Q

What components power the AC system?

A
2 integrated drive generators (IDG)
Auxiliary Power Unit (APU)
Inverter
Ram Air Turbine (RAT)
AC GPU receptacle
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3
Q

What components make up the DC system?

A

2 NiCad batteries
3 Transformer Rectifier Units (TRU)
DC GPU receptacle

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4
Q

How does the IDG maintain a stable power output?

A

A constant speed drive attaches the IDG to the Accessory Gear Box

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5
Q

What monitors and controls the IDGs?

A

Each has a Generator Control Unit (GCU)

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6
Q

Can one IDG supply the entire electrical system?

A

Yes

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7
Q

What will cause the amber IDG light on the overhead panel to illuminate?

A

High oil temperature

Low oil pressure

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8
Q

If an IDG is manually disconnected can it be reconnected by the flight crew?

A

No, it is a maintenance function

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9
Q

What is the primary purpose of the AC generators?

A

To Power the AC BUSSES and AC ESS BUS which powers the 3 TRUs (1,2, and ESS)

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10
Q

What is the purpose of the TRUs?

A

To convert 115 VAC to 28 VDC

300 amps

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11
Q

Can the APU replace a failed IDG?

A

Yes

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12
Q

What is the AC electrical system’s priority?

A

IDG (onside)
APU (inside)
GPU (outside)
Other IDG (cross-side)

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13
Q

How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?

A

GPU button displays AVAIL and GPU icon is presented on the electrical synoptic page. Once the GPU button is pushed in, the button will display IN USE provided another AC power source is not available.

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14
Q

What does it mean if the AC GPU is plugged in and the outside GPU panel button displays IN USE?

A

Ground Service bus is in use

Cockpit GPU button will display AVAIL even though the ground service bus is in use

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15
Q

If the airplane is using the AC GPU and APU is started what should the pilot be sure to do?

A

Deselect the GPU button before the next GPU connection

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16
Q

What will charge the batteries?

A

Any AC power source

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17
Q

How long will the aircraft’s batteries last with no recharging?

A

10 minutes

18
Q

What is the purpose of the DC GPU receptacle?

A

For APU start when the batteries are less than 22.5 VDC or

If battery temp is less than -20 degrees C.

19
Q

What is the minimum battery temp for APU start?

A

-20 degrees C

20
Q

What is the minimum battery voltage to close the battery bus-tie?

A

18 volts

21
Q

What battery is used for the APU start?

A

BATT 2 powers the APU start Bus

BATT 1 powers the FADEC & EICAS for monitoring

22
Q

What is the purpose of the inverter?

A

Converts 28 VDC from the batteries to 115 VAC to power the AC STANDBY BUS when an AC source is not available

23
Q

What is on the AC STANDBY BUS?

A

Engine exciters 1A and 2A

24
Q

What powers the Ram Air Turbine (RAT)?

A

Airflow turns the RAT propeller which spins the turbine inside

25
Q

When will the RAT deploy?

A

Automatically deploys if AC BUSSES are not powered

Manually by pilot

26
Q

How long after deployment before the RAT will supply power?

A

8 seconds

27
Q

Is there a total loss of power during the 8 second RAT deployment?

A

No, Batteries supply power to the DC ESS BUSSES and AC STANDBY BUS

28
Q

What does the RAT power?

A

ESS BUSSES

29
Q

What is the minimum airspeed for the RAT?

A

130 KIAS
Load shedding occurs below this speed
Flaps 3 landing

30
Q

When is the RAT icon displayed on the electrical synoptic page?

A

When the RAT is deployed

31
Q

What manages the electrical system?

A

4 Integrated Control Centers (ICC)

2 Secondary Power Distribution Assemblies (SPDA)

32
Q

What is an ICC?

A

An electrical control device, which provides power distribution and protection for electrical loads

33
Q

What is an SPDA?

A

An electrical load-management unit (powered by the ICC’s) that distributes electrical loads to aircraft systems according to distribution logic

34
Q

Can the flight crew reset the ICC and SPDA remote electronic CBs?

A

ICC CB’s can only be reset by maintenance

SPDA CB’s can be reset via MCDU

35
Q

What are the IDGs rated to?

A

115 VAC
400 Hz
40 KVA

36
Q

What is the APU rated to?

A

115 VAC
400 Hz
40 KVA

37
Q

What is the AC GPU rated?

A

115 VAC
400 Hz
40 KVA

38
Q

What is the RAT rated to?

A

115 VAC
400 Hz
15 KVA

39
Q

What is the inverter rated to?

A

250 VA. AC power ratings are expressed in VA, DC power ratings in W (Watt).

40
Q

How many networks make up the electrical system?why?

A

2.

Redundancy and fault isolation.

41
Q

IDG RPM

A

12,000 RPM