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NCR 744 > 6 - Electrical > Flashcards

6 - Electrical Flashcards

1
Q

What happens when you push the BUS TIE Switches to AUTO? (2)

A
  • ‘ARMS’ automatic AC bus tie circuitry

* ‘CLOSES’ related DC isolation relay (DCIR)

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2
Q

What happens when the Bus Isolation (ISLN) Light illuminates? (2)

A
  • BTB open

* AC bus isolated from synchronous bus

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3
Q

Generator Drive Disconnect (DRIVE DISC) Switches - Push (2)

A
  • disconnects IDG from engine (when above idle speed)
  • opens related Generator Control Breaker (GCB)

Note: Ground maintenance action required to reconnect IDG

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4
Q

What does a Generator DRIVE Light indicate? (3)

A
  • IDG oil pressure low, or
  • IDG oil temperature high
  • GCB open due to uncorrectable generator frequency fault

(EICAS - ELEC DRIVE)

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5
Q

Generator Control (GEN CONT) Switches

ON - (1)

OFF - (3)

A

arms GCB to close when generator power quality acceptable

  • opens generator field and GCB
  • resets fault control logic circuitry
  • isolates generator from its related AC bus
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6
Q

Split System Breaker OPEN Light

Illuminated (white) -

A

split system breaker open

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7
Q

The Electrical synoptic displays the configuration of the AC power system in a _____ schematic format. DC power flow is ___ represented. The depiction is generated by the status of various system breakers and conductors and ______ represent actual power flow. Therefore, the display ______ an accurate representation of system operation

A

simplified

not

does not

does not

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8
Q

The electrical system is ______

Electrical faults are ______ detected and isolated

A

automatic

automatically

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9
Q

Electrical system overload protection is provided by a _____ system configured to ensure power is available to ______ equipment

A

load management

critical and essential

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10
Q

The load management system sheds _____ by priority until the loads are _____ of airplane or ground power generators

A

AC loads

within the capacity

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11
Q

Utility bus loads are shed one at a time through _____ in a programmed sequence until the overload condition is relieved. When an additional AC power source is available, loads are restored in ______
During load shedding, the ELEC UTIL BUS L and R messages and utility off lights are _____

A

ELCUs

reverse order

inhibited

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12
Q

The main AC electrical power sources are: (3)

A
  • four IDGs
  • two auxiliary power sources (APU generators)
  • two external power sources
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13
Q

Each IDG incorporates: _________ with _______ lubricating system and _____ control and protection components

A

AC generator drive unit

self-contained

automatic

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14
Q

Each IDG can be mechanically disconnected from its engine accessory gearbox by pushing the ______

When an IDG is disconnected, generator power output is lost and cannot be _____ by flight crew action

A

Generator Drive Disconnect switch

restored

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15
Q

The EICAS message ELEC DRIVE displays for: (3)

A
  • low IDG oil pressure
  • high IDG oil temperature
  • GCB open due to uncontrollable frequency fault

(Generator DRIVE light illuminates)

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16
Q

Auxiliary power is available only ______ from ___ generator(s) mounted on the APU. External power is available from ground sources through two power receptacles located _______

A

on the ground

2

on the lower right forward fuselage

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17
Q

When cargo handling is required, selecting ______ or _____ ON ensures the main deck cargo handling bus remains powered

A

only the number ONE; auxiliary or external power source

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18
Q

AC power is distributed by the following busses: (6)

A
  • four main busses
  • four utility busses
  • two standby busses
  • two transfer busses
  • ground service bus
  • ground handling bus
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19
Q

Each IDG normally powers its related AC bus through a ______

Each AC bus is connected to the synchronous bus by a ______

A

GCB (Generator Control Breaker)

BTB (Bus Tie Breaker)

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20
Q

If power on an AC bus is unacceptable, the related ____ opens and the bus disconnects from the ______

If the IDG is not able to maintain acceptable power quality, the ____ opens and the ____ closes to provide power from the synchronous bus

A

BTB

synchronous bus. (However, the AC bus remains powered by its IDG)

GCB

BTB

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21
Q

The EICAS message ______ displays if the BTB is open.

Pushing the Bus Tie switch OFF, then AUTO, _______ and allows the BTB to close if the fault is corrected. The AC bus is reconnected to the synchronous bus

A

ELEC BUS ISLN

resets logic circuitry

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22
Q

What powers the ground service bus and provides back-up power for both transfer busses?

A

AC bus 1

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23
Q

What powers the first officer transfer bus?

A

AC bus 2

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24
Q

What powers the captain transfer bus and the main standby bus?

A

AC bus 3

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25
Q

When is the ground service bus powered?

A

any time AC bus 1 is powered (on the ground and in flight)

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26
Q

The ground service bus powers individual equipment items such as: (5)

A
  • main and APU battery chargers
  • fuel pumps for APU start
  • upper deck emergency doors
  • flight deck flood lights
  • miscellaneous service outlets and equipment
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27
Q

The ground handling bus is powered on the ground when ______

If both are available, ______ is automatically used

A

APU generator 1 or External power 1 AVAIL

external power

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28
Q

The ground handling bus powers individual equipment items such as: (3)

A
  • lower cargo handling equipment and compartment lights
  • fueling system
  • auxiliary hydraulic pump 4
29
Q

Two transfer busses provide AC power to _______ equipment.

The transfer busses have a common back-up power source _______

A

critical flight-related

AC Bus 1 (transfer to the back-up power source is automatic)

30
Q

The captain transfer bus is normally powered by ______. If unpowered, ______ powers the captain transfer bus.

The captain transfer bus powers the _____ bus

A

AC bus 3

AC bus 1

APU standby bus

31
Q

The captain transfer bus powers individual equipment items such as: (2)

A
  • center EIU (EFIS/EICAS Interface Unit)

* left HF

32
Q

The first officer transfer bus is normally powered by _______. If unpowered, ______ powers the first officer transfer bus

A

AC bus 2

AC bus 1

33
Q

The first officer transfer bus powers individual equipment items such as: (2/8)

A
  • autothrottle servo
  • lower EICAS display

• right - EFIS, EIU, ADC, PFD, ND
FMC, CDU, HF

34
Q

Each main AC bus powers one utility bus. Each utility bus is controlled by ____ that protects the electrical system from utility bus faults and provides load management through automatic load shedding. With the Left Utility Power switch ON, utility bus(ses) _____ are powered according to ____ logic. With the Right Utility Power switch ON, utility bus(ses) _____ are powered according to _____ logic

A

ELCU

1 and 2

ELCU

3 and 4

ELCU

35
Q

Utility busses power individual equipment items such as: (4)

A
  • forward main fuel pumps 2/3
  • forward override/jettison pumps 2/3
  • center override/jettison pump L
  • galley equipment
36
Q

A main deck cargo handling bus interlock _____ external power 2 or APU generator 2 from powering main electrical busses and the main deck cargo handling bus simultaneously.

Pushing the available power source switch ON _____ the main deck cargo handling bus.

A

prevents

deengergizes

37
Q

When both external power 2 and APU generator 2 are available, _____ is used

A

external power 2

38
Q

The AC standby power system provides electrical power to ______

Major components of the system include: (4)

A

critical flight deck equipment

  • main and APU standby busses
  • main and APU batteries
  • main and APU standby inverters
  • Standby Power selector
39
Q

The main deck cargo handling bus powers equipment items such as: (2)

A

• main deck cargo handling equipment
and lighting

• side cargo door

40
Q

During automatic ILS approach, ____ and ____ busses _____ are isolated from the synchronous bus to provide independent power sources for the three autopilots.
_____ continues to power the synchronous bus.

A

AC and DC

1, 2, and 3

AC bus 4

(If any AC or DC source fails when busses are isolated for autoland, the system reconfigures automatically to maintain independent power sources for the three autopilots)

41
Q

The main standby bus is normally powered by ______

With the Battery switch ON, Standby Power selector in AUTO, and ______ not powered, the main standby bus is powered by ______
Normally unpowered, it is activated and receives power from the _____ through the _____

A

AC bus 3

AC bus 3

main standby inverter

main battery charger

main hot battery bus

(with the main battery charger unpowered, the main battery can provide power to the main standby bus for a minimum of 30 minutes)

42
Q

The main battery charger is normally powered by _______ through the ______

A

AC bus 1

ground service bus

43
Q

The main standby bus powers individual equipment items such as: (3+)

A
  • standby ignition
  • left: EFIS, EIU, ADC, stby instrument lights, primary EICAS, CDU, ILS, VOR, transponder
  • various flight control components
44
Q

The APU standby bus is normally powered by _____

Battery switch ON, Standby Power selector in AUTO, and the captain transfer bus not powered (loss of AC busses 1 and 3), the APU standby bus is powered by ______

A

captain transfer bus

APU standby inverter

45
Q

The APU standby inverter, normally unpowered, when activated receives power from the _____ through the _____

A

APU battery

APU hot battery bus

(With the APU battery charger unpowered, the APU battery can provide power to the APU standby bus for a minimum of 30 minutes)

46
Q

The APU standby bus powers these equipment items: (3)

A

left - PFD, ND, FMC

47
Q

The main DC electrical system uses _____ to produce DC power.

Each ______ is powered by ______ and provides DC power to a DC bus

A

four transformer-rectifier units (TRUs)

TRU

its related AC bus

48
Q

The four DC busses are connected through _____ to the DC tie bus, which allows each DC bus to remain powered if its related AC bus is unpowered or _____ fails

Pushing the Bus Tie switch to AUTO closes the related _____ and _____

A

DC isolation relays (DCIRs)

TRU

BTB

DCIR

49
Q

Pushing the Bus Tie switch OFF opens the _____ and ______

This isolates the DC bus from the DC tie bus, leaving it powered by its ______ and ____

Automatic isolation of an AC bus due to an electrical fault opens the ____ , but does not open the ______

A

BTB and DC Isolation Relay (DCIR)

AC bus and TRU

BTB

DC Isolation Relay (DCIR)

50
Q

TRU DC electrical power is distributed to _____ main DC busses. Main DC busses power individual equipment items such as:

A
  • cabin pressure, fuel jettison, and pack temperature controllers
  • wing anti-ice control
  • engine-driven and hydraulic demand pump control
  • fuel transfer and jettison valve control
51
Q

The main and APU battery busses are normally powered by ______

If either _______ or ______ is unpowered, each battery bus is powered by its related hot battery bus

A

DC bus 3

AC bus 3

DC bus 3

52
Q

The main battery bus provides power to individual equipment such as:

A
  • APU controller (alternate), fuel valves (all engines), all crossfeed valves
  • dome, storm, and selected indicator lights

• IDG disconnect (all engines), manual pressurization control, trailing edge flap control
(N919CA)

• captain interphone, left radio tuning panel, left VHF

53
Q

The APU battery bus powers individual equipment items such as:

A
  • APU DC fuel pump, engine start air control
  • cargo, first officer, service interphones, and PA system
  • APU and engine fire/overheat detection loops A and B

• APU fire warning horn
(N952CA)

• captain interphone, left radio tuning panel, left VHF, nacelle anti-ice control (all engines)

54
Q

Each hot battery bus is normally powered by the _______ through _______, which acts as a TRU for the hot battery bus while simultaneously maintaining its related battery fully charged

Each battery is directly connected to its related ________

A

ground service bus

its related battery charger

hot battery bus

55
Q

With the Battery switch ON, the main and APU hot battery busses power their related battery busses if either ______ or ______ is unpowered

A

AC bus 3

DC bus 3

56
Q

The main hot battery bus powers individual equipment items such as:

A
  • APU fuel shutoff valve, spar valves (all engines)
  • APU and lower cargo fire extinguishers
  • engine fire extinguishers (all engines), fire switch unlock (all engines)
57
Q

The APU hot battery bus powers individual equipment items such as:

A
  • IRU left, center, right DC power
  • left and right outflow valves
  • APU inlet door, APU controller (primary)
58
Q

What are the main items power by the Ground Handling Bus?

A
  • lower cargo doors, lights and handling equipment
  • fueling system
  • aux hydraulic 4/(1)
59
Q

How is the Ground Handling Bus powered?

Is it powered on the ground or in-flight?

A

EXT 1/APU 1 - AVAIL or ON

on the ground only
no controls or indicators

60
Q

What are the main item powered by the Ground Service Bus? (3)

A

main/APU battery chargers

fuel pump for APU start

flight deck flood lights

61
Q

How is the Ground Service Bus powered?

Is it powered on the ground or in-flight?

A

AC Bus 1 or Ground Handling Bus power source if Ground Service switch on cabin panel is ON

both
(no controls or indicators)

62
Q

How is the Main Deck Cargo Handling Bus powered?

A

EXT/APU AVAIL only

EXT has priority

63
Q

What is powered by the Main Stby Bus? (4)

A

Stby ignition

Primary EICAS

Left - EFIS, EIU, ADC, CDU, ILS, VOR, transponder

various flight control components

64
Q

What is powered by the Standby Power System? (4)

A

CA’s:

PFD
ND
Upper EICAS
CDU

65
Q

What is available with (only) BATT Switch ON?

A

L/R/Aisle Stand flood lights, Interphone, PA, L VHF/Radio Tuning Panel

66
Q

What does Hot Battery Bus power with no electrical power to A/C?

A
  • APU Fire Warning and shutdown controls
  • Engine, APU and lower cargo fire extinguishers
  • L/R outflow valves
  • IRS DC power (if IRS selectors are on
67
Q

STBY Power AUTO and BATT Switch ON; what is powered?

A

CA PFD/ND

Upper EICAS

L CDU

(using battery power/stby inverters)

68
Q

What is the normal power source for the MAIN and APU Battery Buses?

A

DC Bus 3

NCR 744 (23 decks)

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