Electrical Questions Flashcards

1
Q

How man networks make up the electrical system on the airplane? Why?

A
  • 2 independent networks

- Redundancy and fault isolation

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2
Q

What happens if a power generating source fails?

A
  • BUS ties automatically connect to provide no system degradation
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3
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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4
Q

What components power the DC system?

A
  • 2 NiCad batteries
  • 3 transformer rectifier unit (TRU)
  • DC GPU receptacle
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5
Q

How does the IDG maintain a stable power output?

A
  • A constant speed drive (CSD) attaches the IDG to the AGB (Accessory Gear BOX)
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6
Q

What monitors and controls the IDG’s?

A
  • Each has a Generator control unit (GCU)
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7
Q

Can one IDG supply the entire electrical system?

A

Yes

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8
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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9
Q

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

A
  • No. This is a maintenance function
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10
Q

What is the primary purpose of the AC Generators?

A
  • To power the AC BUSSES and AC ESS BUS

- Power the 3 transformer rectifier units (TRU) 1,2 and ESS

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11
Q

What is the purpose of the transformer rectifier unit?

A
  • To convert 115 VAC to 28 VDC
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12
Q

Can the APU replace a failed IDG?

A
  • Yes
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13
Q

What is the AC electrical system priority?

A
  • Onside (IDG)
  • Inside (APU)
  • Outside (GPU)
  • Cross-side (other IDG)
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14
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 the 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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15
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 the use

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16
Q

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

A
  • Deselect the GPU button before the next GPU connection
17
Q

What will charge the batteries?

A
  • Any AC power source
18
Q

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

A
  • 10 min
19
Q

What is the purpose of the DC GPU receptacle?

A
  • For APU start when batteries < 22.5 VDC or

- If battery temp os < -20 C

20
Q

What is the minimum battery temp for APU start?

A

-20 C

21
Q

What is the minimum battery voltage to close the battery’s-ties?

A

18 Volts

22
Q

What battery is used for the inverter?

A
  • BATT 2 powers the APU start BUS

- BATT 1 powers the FADEC & EICAS for monitoring

23
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 and AC source is not available
24
Q

What is the AC STANDY BUS?

A
  • Engine exciters 1A and 2A
25
Q

What powers the Ram Air Turbine (RAT)?

A

Airflow turns the RAT propeller which spins the turbine inside

26
Q

When will the RAT deploy?

A
  • Automatically deploys if AC BUSSES are not powered

- Manually by pilot

27
Q

How long after deployment before the RAT will supply power?

A
  • 8 Seconds
28
Q

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

A
  • No. Batteries supply power to the DC BUSSES and AC STANDBY BUS
29
Q

What does the RAT power?

A
  • ESS BUSSES
30
Q

What is minimum airspeed for the RAT?

A
  • 130 Kias

- Load shedding occurs below 130 Kias

31
Q

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

A
  • When the RAT is deployed
32
Q

What manages the electrical system?

A
  • 4 Integrated Control Centers (ICC)

- 2 Secondary power distribution assembles (SPDA)

33
Q

What is an ICC?

A
  • An electrical control device, which provides power distribution and protection for electrical loads.
34
Q

What is an SPDA?

A
  • An electrical load-management unit (powered by the ICC’s) that distributes electrical loads to the aircraft systems according to distribution logic.
35
Q

Can the flight crew reset the ICC and SPDA remote electronic CB’s?

A
  • ICC CB’s can only be reset by maintenance

- SPDA CB’s can be reset via the MCDU