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Sovereign Electrical System Flashcards

1
Q

What is a SPLIT Bus system?

A

Left and Right Electrical Buses are isolated from one another

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2
Q

What does the GCU do?

A
  1. Regulates voltage to 28.5 V
  2. Protects

U-R Under-voltage or Reverse Current Opens GEN relay
O-F-F Over-voltage, Feeder Fault or Fire Button Opens Field relay

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3
Q

How long will the batteries power the entire electrical system?

A

20 minutes

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4
Q

How long will the batteries power the electrical system after Load Shedding (L ELECT and R ELECT Buttons to EMER)?

A

1 hour

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5
Q

What causes the AVAIL light to illuminate?

A

GPU output is between 26.5 and 32 volts

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6
Q

What does the BUS TIE relay do?

A

Allows the entire electrical system to be powered from 1 generator

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7
Q

How can you confirm the GPU is disconnected?

A
  1. AVAIL light extinguishes and

2. Visual conformation

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8
Q

What does the INTERIOR Button do?

A

NORM - Turns ON Cabin electrical power

OFF - Turns OFF all electrical power to the Cabin

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9
Q

What is on the Right CB Panel?

A

Respective Right:
Main DC Bus
EMER Bus
Avionics Bus

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10
Q

What is on the Left CB Panel that’s not on the right?

A

Standby Instrument Bus

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11
Q

What bus must be powered for Cabin Entry Lights?

A

Right Battery Bus

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12
Q

When will the EMER lights illuminate?

A 
1. EMER lights switch ON
With EMER lights switch in the ARM position:
2. PAX SAFETY ON
3. Loss of Main DC Bus power
4. 5 G impact
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13
Q

What causes a RED BATTERY O’TEMP CAS message?

A

> 63 degrees C and assuming the first activation was reset the warning will recur > 71 degrees C

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14
Q

What should you do if you get a BATTERY O’TEMP on the ground?

A
  1. Unload Battery(ies)

2. Call Maintenance

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15
Q

Where do the EMER Lights get there Power from?

A

4 NICAD battery packs located above the ceiling panels in the Cabin

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16
Q

How long will EMER Lights last?

A
  1. Indefinitely using Main DC Bus power
  2. 60 minutes using EMER Bus power
  3. 10 minutes using Battery Packs
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17
Q

With the AVAIL light illuminated what happens when the EXT PWR Button is pressed?

A

Connects the GPU to the right EMER Bus

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18
Q

When the APU READY TO LOAD light is illuminated what happens when the APU GEN Button is selected ON?

A

Connects the APU generator to the Left EMER Bus

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19
Q

What Bus is powered when a battery is connected?

A

Respective BATT BUS

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20
Q

What happens when either the Left or Right BATT Button is selected ON?

A

Respective BATT relay closes connecting the BATT BUS to it’s respective EMER BUS and via the BUS TIE relay powers the opposite EMER BUS

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21
Q

Explain the logic of the BUS TIE relay?

A

On the ground the BUS TIE will automatically OPEN or CLOSE based on single primary power source and Engine or APU Start logic. In flight the BUS TIE is manually actuated.

Note: In flight, if the BUS TIE has been manually CLOSED, the BUS TIE will automatically OPEN for an Over Current (>600 amps) condition

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22
Q

How does the Main DC Bus receive power?

A

From its respective EMER BUS via its ELEC relay

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23
Q

What is the NORMAL position of the ELECT relays?

A

Closed (could also be referred to as Load Shedding relays)

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24
Q

What items are on the Left BATT BUS?

A
  1. AFT BAGGAGE Lights
  2. TAIL CONE Lights
  3. APU Test Panel
  4. NWS Accumulator Bleed
  5. Battery Voltage
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25
How many AMPS should the GPU be set to for Engine Start?
1000 to 1500 amps
26
What is on the Right BATT BUS?
1. Cabin Entry Lights 2. Under Pylon Lights 3. LAV Service 4. ELT Panel 5. Battery Voltage
27
Which Buses do the BUS TIE relay connect?
Left and Right EMER BUS
28
What happens to the APU generator when the Left Engine Generator comes on-line and why?
APU relay opens, because of priority logic and only 1 power source on that sides Bus at a time.
29
What monitors the Electrical System?
MAU's
30
What does a DC-DC Convertor do?
Maintains 24 Volts minimum during Engine Start
31
What powers EICAS?
Right EMER BUS
32
When does the BUS TIE close automatically?
On the ground ONLY: 1. When the Engine or APU start Button is pressed 2. Whenever a Single Primary Power Source is selected
33
With AVAIL illuminated what should the BATT VOLTS indicate?
28V
34
Why is APU limited to 275 amps?
Cooling issue, otherwise it's the same generator that's on the Engine
35
When must the BUS TIE be manually selected?
In Flight
36
Do the batteries effect BUS TIE operation?
No
37
What are the Primary Electrical Sources?
Engine Generators APU Generator GPU
38
How are the power sources prioritized?
Respective Engine has priority over APU and GPU
39
What happens if the BUS TIE remains closed on the ground with both engines running and respective generators supplying power?
An amber BUS TIE CLOSED message will appear on EICAS indicating the malfunction
40
When should you Manually Close the BUS TIE in flight?
To Start an Engine or APU
41
When is the DC GEN O'CURRENT EICAS message inhibited?
Engine Start + 2 minutes
42
What Flight Controls are on the EMER BUS?
Aileron Trim Rudder Trim Secondary Pitch Trim Rudder Bias O'RIDE
43
Does the Ignition System work on EMER power?
Yes
44
Do Fan Air valves for Pylon Pre-cooler cooling air operate on EMER power?
Yes
45
Which bus is Fire Detection on?
EMER BUS
46
On what bus is the Fuel and Hydraulic SOV?
EMER
47
On what bus is the Anti-Skid System?
EMER
48
What amperage should the battery be at prior to Takeoff and why?
20 amps, to ensure the batteries are fully charged in case you need emergency power
49
What is the maximum amps prior to the second Engine Start ?
100 amps
50
Does the BUS TIE work manually on the ground?
No, not even if the button illuminates when pressed
51
What does REMOTE CB TRIPPED EICAS message indicate?
CB on the aft J-Box has tripped Note: Not all CB's on the aft J-Box are monitored
52
Are the CB's on the Cabin J-Box monitored?
No, non-essential items for flight (DVD, LAV motor, Coffee Warmer, etc.)
53
What lights in the cabin would still come ON even with the INTERIOR light Button selected OFF?
Entry Lights and | EMER Lights
54
Which source of power is always used for Engine Start?
Batteries
55
Are engine generators ever used for Start in flight?
Never
56
When would you see Both START Buttons illuminate?
Cross generator start
57
What would happen if you Close the BUS TIE in flight and forget to re-open it?
The cyan BUS TIE CLOSED message would turn amber after 5 minutes
58
On what bus are the Thrust Reversers?
Main DC
59
You just started the right engine with the GPU and the Engine Generator is now On. What happens to the GPU?
GPU relay opens and AVAIL light illuminates
60
Why must the batteries be installed for the APU to operate?
Required for Fire Protection
61
Why is the battery volt meter on the BATT BUS?
To display Voltage during a BATT O'TEMERATURE, as the procedure require the battery be turned OFF
62
How many 5 G switches are there?
4, 1 for each Battery Pack
63
Why is it a good idea to start the right engine first when the APU is running?
You will charge the batteries quicker, using engine generator on the Right bus AND the APU generator on the Left bus
64
Why is it a good idea to start the left engine first when using a GPU?
You will charge the batteries quicker by using the engine generator on the Left bus AND the GPU on the Right bus
65
How do you know if the battery is really OFF after completing a BATT O'TEMERATURE procedure
1. BATTERY OFF L-R message, and | 2. No amp indication ((+/- 0)
66
On the ground after the second Engine Start, what can you try if the BUS TIE doesn't open automatically and you get an amber BUS TIE message?
Turn 1 Generator OFF, the BUS TIE message turns cyan, then turn the generator back ON and it should Force the BUS TIE open
67
How quickly must you react after a dual generator failure to get the full 60 minutes on the batteries?
EMER must be selected within 5 minutes
68
Why turn OFF the X-FEED after a dual generator failure?
To turn off the Standby Fuel Pump, a big draw item
69
Why should we leave icing conditions when on EMER power?
1. No Windshield Heat | 2. No EICAS, therefore no CAS to inform us on anti-ice system condition
70
What powers Flaps?
Main DC
71
What powers NWS?
Main DC
72
Do SPEED BRAKES/SPOILERS work on EMER power?
No
73
What is the Engine Start Primary assist sequence during Start?
1. GPU 2. APU Generator 3. Engine Generator
74
You just switched to EMER power, what must you do?
Advise ATC Note: Navigation is impaired, may need to request an altitude below FL200, diversion and priority handling may be required and exterior Lights are inoperative
75
What happens to the X-FEED valve when EMER power is selected?
Fails in last position
76
Does the autopilot work on EMER power?
No
77
What are the Primary uses for the batteries?
Engine or APU Start and EMER power
78
What powers FADEC during Engine Start?
START BUS up to 25%N2, then it reverts to its own PMA
79
What are STBY annunciators for?
Provides redundancy from independent sensors for FUEL LOW, STAB, GEN OFF and OIL PRESS warnings. All powered from the EMER Buses
80
Why does DUAL GENERATOR FAILURE procedure tell you to turn the EICAS OFF
Too much bogus information, better to have it OFF
81
Describe the Main Batteries?
25 Volt / 44 Amp/Hour Nicads
82
What are the advantages of a NICAD battery over Lead Acid?
1. Will hold Voltage longer and then drop off quickly 2. Can accommodate more Discharge and Charging cycles 3. Charges faster

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