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Systems > Electrical > Flashcards

Electrical Flashcards

1
Q

What is the purpose of the DC GPU receptacle

A

For APU start

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2
Q

Can you use the DC GPU to start the APU

A

YEs, as long as BATT 1 still works.

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3
Q

What does the AC System compose of

A
  1. 2 IDG
  2. APU
  3. AC External power receptacle
  4. RAT
  5. Inverter
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4
Q

What does the DC System compose of

A
  1. 2 22.5v NiCad Batteries
  2. DC External Receptacle
  3. 3 TRUs
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5
Q

Placing the IDG in the OFF position does what to the system?

A

It isolates that generator from its bus.

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6
Q

Placing the IDG in the DISC position does what?

A

It disconnects the IDG from Accessory gear box

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7
Q

Placing the AC BUS TIES in the open position does what?

A

It segregates that bus from the rest of the system

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8
Q

When does the available light illuminate in the AC GPU button

A

when ground power is properly suppling the correct Voltage, Amps, frequency to the system.

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9
Q

What happens when you place the TRU switch in the off position?

A

It isolates that TRU from its reactive bus.

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10
Q

Putting the DC BUS TIES in OFF position does what?

A

It opens the Ties removing them from the Auto logic.

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11
Q

When would the IDG Icon be White

A

When switch is in the off position or engine not running.

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12
Q

When would the AC GPU be white

A

When power is connected but the button is not pushed in.

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13
Q

What voltage does the battery ICON Turn white

A

Below 18v

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14
Q

The IDGs and APU Generator is rated at?

A

115V, 40kva, 400hz

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15
Q

When does the RAT come out?

A

When both AC BUS 1 and AC BUS 2 are not being powered

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16
Q

What BUS does the RAT power?

A

AC ESS BUS

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17
Q

When you get an IDG 1 (2) OIL EICAS msg, what other indication do you get

A

an amber light next to the IDG telling you which one to disconnect.

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18
Q

If disconnecting the IDG hold it for how many seconds

A

Hold it for 1 seconds. No more than 3 seconds.

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19
Q

Does the IDG auto disconnect?

A

Yes, IDG oil temperature reaches 366°F

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20
Q

Lets say your on AC ground power and you start the APU what does the auto logic do?

A

It removes the ground power and has the APU take over the electrical system, the ““IN USE” white light of the GPU turns to “AVAIL”. You must push out that button.

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21
Q

How can ground personnel have power to light up the plane for cleaning.

A

push the button on the front ramp panel or on the flight attendant panel at the forward right galley.

22
Q

What does the Inverter do?

A

Converts DC Power to AC power to power the AC STBY BUS

23
Q

What electrical power does the RAT provide

A

115v, 15kva, 400hz

24
Q

How long does it take the RAT to power and what does it power?

A

It powers the AC ESS BUS and it takes 8 seconds.

25
Q

When total electrical failure occurs and the RAT pops out, what powers the system while the RAT comes online

A

The batteries Power the DC ESS BUSes and also power the AC STBY BUS via the inverter.

26
Q

What basic Items does the RAT provide power to

A
  1. ACMP 3A
  2. High lift devices.
  3. Avionics
  4. Communication and
  5. Battery Recharging.
27
Q

What is the Minimum speed for the RAT? And what happens if we go below that?

A

130kts. If we below that speed, the RAT can only Power the AC ESS BUS and the batteries will provide power to the DC ESS BUSES eventually load shedding.

28
Q

The DC GPU can supply power to only what BUS

A

The APU START BUS only.

29
Q

What do the TRUs do?

A

They convert 115v AC power to 28v DC power for the DC system, at 300 amps

30
Q

What happens if one TRU fails?

A

As long as the system is in auto, the ties will close to have no systems degradation.

31
Q

Explain the Batteries

A

2 NiCad batteries rated at 22.8v 27 Amps, they can be charged by any AC source.

32
Q

The batteries can provide Emergency power for how long?

A

10 minutes

33
Q

What is the min temperature to use the batteries

A

-20

34
Q

On the ground if the batteries are the only source of power a horn will sound after?

A

5 minutes

35
Q

When would you use A DC GPU for APU Start?

A

if the outside temp is less than -20, or Battery 2 is less than 21 volts

36
Q

What will cause an Amber Light on the IDG panel?

A

High Oil Temp

Low Oil Pressure

37
Q

Can an APU replace a Failed IDG, up to what Altitude

A

yes, up to 33,000 feet.

38
Q

What is the AC electrical Power Priority

A
  1. Onside IDG
  2. APU
  3. GPU
  4. Opposite Side IDG
39
Q

How do you know if the GPU is ready to provide AC electrical load?

A

You get the “AVAIL” light on the over head panel and the GPU shows up on the EICAS Page.

40
Q

What batteries are used for APU start?

A

Both batteries are used.
BAT 1 Powers EICASE and FADEC
BAT 2 powers the APU START BUS

41
Q

What is the purpose of the inverter and what does it power.

A

It converts 28VDC to 115VAC it powers the AC STANDBY BUS any time AC power is not available.

The AC STANDBY BUS has the Igniters for DC Engine start.

42
Q

What is on the AC STANDBY BUS

A

Engine exciters 1A and 2A

43
Q

When will the RAT deploy?

A
  1. Any time the AC BUSES are not boing powered.

2. Manually by the pilot

44
Q

Why does BATT 2 Normal position AUTO

A

Because it isolates the APU BUS for APU starts and acts as a backup to the DC ESS BUSES. Also for DC GPU start.

45
Q

When only the Batteries are powering the system what do you see in the cockpit

A
  1. Screens 2 and 3
  2. IESS
  3. CLOCK
  4. MCDU #2
  5. Compass Light
46
Q

Can one AC power source power the entire system?

A

yes

47
Q

What are the batteries rated at?

A

22.8v and 27 amps.

48
Q

What 2 EICAS messages do you see when you are on RAT power.

A
  1. Emergency Power

2. BATT DiSCH -> this goes away when RAT is powering AC ESS BUS

49
Q

What speed do you need to be at when the RAT comes out for it to power the system?

A

150kts when it first comes out. Once out than 130kts.

50
Q

If the RAT is deployed, does it give you back the AC ESS BUS if you establish AC power with APU or IDG?

A

No, once RAT comes out it locks into AC ESS BUS and does not let go.

51
Q

How do the batteries get charged during Electrical Emergency Condition (RAT is out)

A

The RAT power the AC ESSN BUS, the AC ESS BUS power the TRU ESS which than charge the batteries, and the BATT DISC message goes away.

52
Q

Describe the IDG Switch Positions?

A
  • Off - Disconnects IDG From the BUS
  • Auto - Allows IDG to pick up power per power priority.
  • DISC - Spring loaded switch. disconnects from Engine.

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