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B737 > electrical > Flashcards

electrical Flashcards

1
Q

what does the Frequency Meter display indicates ?

(n4 on picture)

A

indicates frequency of source selected by AC meters selecters

page 6.10.3

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2
Q

when does the Battery Discharge AMBER Light illuminate ?

A

when excessive battery discharges is detected

with BATT switch ON

page 6.10.3

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3
Q

when does the TR Unit AMBER Light illuminate ?

A

on the ground - ANY TR has FAILED

in flight - TR 1 has FAILED

or

TR 2 and 3 have FAILED

page 6.10.3

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4
Q

when does the Electrical AMBER Light illuminate ?

A

when there is a FAULT in the :

  • DC power system

or

  • STDBY power system

page 6.10.3

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5
Q

what happens when the BATT is switch to OFF with normal power source available (GEN DRIVE ON) ?

A

removes power from:

  • battery bus

and

  • hot battery bus

page 6.10.3

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6
Q

what happens when BATT is switched OFF when the BATT is the ONLY power source ?

A

removes power from :

  • battery bus
  • hot battery bus
  • DC standby bus
  • static inverter
  • AC standby bus
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7
Q

what happens when the BATT switch is in the guarded position, ON ?

A

battery provides prower to :

  • hot battery bus
  • energenzes relays to provided automatic switching to STBY ELEC SYSTEM with loss of normal power (GEN PWR)

page 6.10.3

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8
Q

what does the CAB/UTIL switch do when in ON/OFF position ?

A

provides and removes electrical power from galley and cabin equipment system

page 6.10.4

( - all 115V AC galley busses

  • cabin recirculation fan
  • fwd and aft door area heaters
  • drain mast heaters
  • lavatory water heaters
  • logo lights
  • potable water compressor
  • 115V AC shaver outlets when installed )
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9
Q

what does the IFE/PASS SEAT Switch ON/OFF position do ?

A

provides and removes electrical power from installed components of the pax seats, in-flight entertainment and power system :

  • 115V AC audio entertainment equipment
  • 115V AC video entertainment equipment
  • cabin telephone equipment
  • FAX machine
  • 28V DC video equipment and passenger seat electronic outlets
  • ACARS printer

page 6.10.4

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10
Q

what causes the Amber Drive Light to come on the Generator Drive and Standby Power Panel ?

A

Integrated Drive Generator Low Oil Pressure

page 6.10.5

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11
Q

when the Amber Drive Light on the Generator Drive and Standby Power Panel illuminates a IDG Low Pressure is detected, what is this caused by ?

A
  • IDG failure
  • engine shutdown
  • IDG automatic disconnect due to high oil temperature
  • IDG disconnected through generator drive DISCONNECT switch

page 6.10.5

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12
Q

what does the Generator Drive Disconnect Switch do ?

A

disconnects IDG if:

  • electrical power is available

and

  • engine start lever is IDLE

page 6.10.5

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13
Q

what causes the STANDBY Power OFF Amber Light to illuminate ?

A

one or more of those busses are UNPOWERED:

  • AC standby bus
  • DC standby bus
  • Battery bus

page 6.10.5

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14
Q

what happens when the Standby Power Switch is on the Unguarded BATT position ?

A

Battery powers:

  • DC standby bus
  • AC standby bus via Inverter
  • Battery bus

page 6.10.6

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15
Q

what happens when the Standby Power Switch is the OFF centre position ?

A

NO POWER to :

  • AC standby bus or Inverter
  • DC standby bus

page 6.10.6

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16
Q

what happens when the Standby Power switch is in the AUTO guarded position with AC Transfer Busses powered by the IDG ?

A
  • AC Transfer Bus 1 powers AC STBY BUS
  • TR 1, TR2, TR3 power DC STBY BUS

page 6.10.6

( AC Transfer Bus 1 powers TR 1

and

AC Transfer Bus 2 powers TR 2 and TR 3 )

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17
Q

what causes the GRD PWR AVAILABLE Blue light to illuminate ?

A

ground power is connected

page 6.10.7

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18
Q

how many position does the Ground Power Switch have ? is it spring-loaded to neutral ?

A

three position: ON, OFF, Neutral

YES is spring-loaded

page 6.10.7

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19
Q

what does the OFF position of the Ground Power Switch do ?

A

disconnects ground power to AC transfer busses

page 6.10.7

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20
Q

what does the ON position of the Ground Power Switch do ?

A
  • removes any other previously connected power from AC transfer busses
  • connects ground power to AC transfer busses

(if power quality is good)

page 6.10.7

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21
Q

when does the TRANSFER BUS OFF Amber Light illuminate ?

A

related transfer bus is not powered

page 6.10.7

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22
Q

when does the SOURCE OFF Amber Light illuminate ?

A

no source is powering the related transfer bus

page 6.10.7

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23
Q

how many positions does the Generator Switches have ? is it spring-loaded ?

A

three positions : ON, OFF, Neutral

YES is spring-loaded

page 6.10.7

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24
Q

what happens when the GEN Switch is in the OFF position ?

A

disconnects IDG from related AC Transfer Bus

page 6.10.7

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25
Q

what happens when the GEN Switch is in the ON position ?

A
  • connects IDG to related AC Transfer Bus
  • disconnects previous power source

page 6.10.7

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26
Q

what happens when the BUS TRANSFER Switch is in the AUTO guarded position ?

A

BTBs operate automatically to maintain power to AC transfer busses from any operating generator or external power

page 6.10.8

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27
Q

what happens when the BUS TRANSFER Switch is in the OFF position ?

A

isolates AC transfer bus 1 from AC transfer bus 2 if only one IDG is supplying power to both AC transfer busses

page 6.10.8

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28
Q

what does it mean when the APU GEN OFF BUS Blue Light illuminates ?

A

APU is running and available but not powering any bus

page 6.10.8

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29
Q

how many positions does the APU GEN Switch have? is it spring-loaded ?

A

three positions: ON, OFF, Neutral

YES is spring-loaded

page 6.10.8

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30
Q

what happens when the APU Generator is powering both AC Transfer Busses and one APU GEN Switch is moved to OFF position ?

A
  • related SOURCE OFF Amber Light illuminates
  • APU continues to power both transfer busses

(the other switch that is still ON takes over the load of both busses)

page 6.10.8

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31
Q

what happens when the APU Generator is powering both AC Transfer Busses and both APU GEN Switches are moved to OFF position ?

A
  • APU GEN is disconnected from tie bus

and

  • power to the AC Transfer Bus from APU GEN is removed

page 6.10.8

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32
Q

what happens when the APU Generator is powering one AC Transfer Bus and the IDG is powering the other AC Transfer Bus and the related APU GEN Switch is moved to OFF position ?

A
  • APU Generator is disconnected from tie bus and AC Transfer Bus

and

  • IDG powers both AC Transfer Busses

page 6.10.8

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33
Q

what happens when neither AC Transfer Busses are powered by IDG and one APU GEN Switch is moved to ON ?

A
  • connects both AC transfer busses to the APU generator
  • disconnects external power, if connected
  • opposite SOURCE OFF light illuminates until the other APU GEN

page 6.10.8

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34
Q

what happens when both AC Transfer Busses are powered by both IDGs and one APU GEN Switch is moved to ON ?

A
  • powers the related AC transfer bus from the APU generator
  • other AC transfer bus continues to receive power from the IDG

page 6.10.8

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35
Q

what does the Ground Service button do ?

A
  • Provides manual control of ground service busses
  • Enables servicing airplane using external power without activating AC transfer busses

page 6.10.9

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36
Q

what happens when the Ground Service Switch is ON ?

A

connects external power to ground service busses

page 6.10.9

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37
Q

what happens when the Ground Service Switch is OFF ?

A

disconnects external power from ground service busses

page 6.10.9

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38
Q

when does the Ground Service Switch illuminate white ? when ON or OFF ?

A

both when ON or OFF

after being pressed to be switched ON and then being pressed again to be switched OFF

page 6.10.9

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39
Q

what is the primary electrical power provided by ?

A

2 engine integrated drive generators (IDG)

page 6.20.1

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40
Q

how many phases of AC do the two IDGs provide ?

A

three phases

page 6.20.1

41
Q

what is the volt of the AC system ?

A

115V

page 6.20.1

42
Q

how many cycle does the AC have ?

A

400 cycles

page 6.20.1

43
Q

how many bus systems can one IDG supply ?

A

up to two

page 6.20.1

44
Q

what type of power do the Transformer Rectifiers n1/2/3 provide ?

A

DC power

(they rectify AC power to DC )

page 6.20.1

45
Q

which components does the TR1/2/3 provide DC power to ?

A
  • DC bus 1
  • DC bus 2
  • DC standby bus
  • Battery bus

page 6.20.2

46
Q

can the main and auxiliary batteries provide back up power to both AC and DC ?

A

YES

page 6.20.1

47
Q

can the APU provide power to both AC Transfer Bussed both on the ground and in flight ?

A

YES

almost all phases of flight

page 6.20.1

48
Q

what are the two basic principles of the 737 electrical system ?

A
  • there is no paralleling of the AC power sources
  • the source of power being connected to an AC Transfer Bus automatically disconnects the previous existing source

page 6.20.1

49
Q

can the IDG maintain a constant speed regardless of the engine rpm ?

A

YES

page 6.20.1

50
Q

how can a IDG being mechanically isolated from the electrical system ?

A

via a electro-mechanical disconnect device

page 6.20.1

51
Q

where is the external AC power located ?

A

near the nose gear wheel well, on the lower right side of the fuselage

page 6.20.1

52
Q

can the external AC power supply both AC Transfer Busess ?

A

YES

page 6.20.1

53
Q

what are the components of the the AC power system ?

A
  • two transfer busses
  • two main busses
  • two galley busses
  • two ground service busses

page 6.20.3

54
Q

If the AC source powering either transfer bus fails or is disconnected, what can the transfer buses be powered by ?

A

any available source through the tie bus with the bus tie breakers (BTBs)

page 6.20.3

55
Q

is it possible to power one transfer bus with external power and one transfer bus with APU power ?

A

NO is not

page 6.20.3

56
Q

is it possible to power one transfer bus with GEN DRIVE and one the other transfer bus with external power or with APU power ?

A

YES it is

page 6.20.3

57
Q

what happens if during normal operations with both IDGs ON, one IDG is no longer supplying power ?

A

the BTBs automatically close to allow the other engine generator to supply both transfer busses through the tie bus and BTBs

page 6.20.3

58
Q

can the APU provide power to both AC Transfer Buses if one fails ?

A

YES

via the BTB

page 6.20.3

59
Q

what is that feature that is part of the electrical system in case taking off with the APU still powering both busses ?

A

an automatic generator on-line feature

page 6.20.3

60
Q

in case of take off with APU still powering the transfer bussed the automatic gernerator on-line feature will turn the GEN ON, when does this also happen ?

A

If the APU is either shut down or fails, the engine generators are automatically connected to their related transfer busses

page 6.20.3

61
Q

how does the Automatic Load Shedding (engine generators) work ?

A

For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing.

The galleys and main bus on transfer bus 2 are shed first; if an overload is still sensed, the galleys and main bus on transfer bus 1 are shed; if overload still exists, the IFE buses are shed.

When configuration changes to more source capacity (two generator operation), automatic load restoration

page 6.20.4

62
Q

does the APU have a Automatic Load Shedding system ?

A

YES

in flight - when is the only source of electrical power

on ground - APU attemps to carry a full electrical load

page 6.20.4

63
Q

simply describe the IDGs system ?

A

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a self–contained oil system.

An integral electro–mechanical disconnect device provides for complete mechanical isolation of the IDG.

page 6.20.5

64
Q

is it true that the frequency display only shows a reading when the generators are electrically excited ?

A

YES it true

page 6.20.6

65
Q

briefly describe the DC power system

A

28 volt DC power is supplied by three TR units, which are energized from the AC transfer busses.

page 6.20.7

66
Q

what is the aim of the Transformer Rectifier Unit ?

A

to convert 115 Volt AC to 28 Volt DC

page 6.20.8

67
Q

where does the TR 1 receive AC power from ?

A

AC Transfer Bus 1

page 6.20.8

68
Q

where does the TR2 receive AC power from ?

A

AC Transfer Bus 2

page 6.20.8

69
Q

where does the TR3 receive AC power from ?

A

AC Transfer Bus 2 with AC Transfer Bus 1 as buck up

page 6.20.8

70
Q

what do TR1 and TR2 provide power to ?

A
  • DC bus 1
  • DC bus 2
  • DC standby power

page 6.20.8

71
Q

what does the TR 3 provide power to ?

A
  • powers the battery bus
  • back up power for TR1 and TR2

page 6.20.8

72
Q

what are the conditions by which the cross bus tie relay (between TR1 and TR2/3) automatically opens, isolating DC bus 1 (TR1) from DC bus 2 (TR2/3) ?

A
  • At glide slope capture during a flight director or autopilot ILS approach.

(This isolates the DC busses during approach to prevent a single failure from affecting both navigation receivers and flight control computers)

and

  • Bus transfer switch positioned to OFF

page 6.20.8

73
Q

how many batteries does the 737 electrical system have ?

A
  • 2 nickel-cadmium batteries
  • one main
  • one auxiliary

page 6.20.8

74
Q

what is the volts of the two batteries ?

A

24 volts

page 6.20.8

75
Q

can the batteries supply the entire electrical system ?

A

NO

only part of the DC system

page 6.20.8

76
Q

in which situation does the auxiliary battery operate in parallel with the main battery ?

A

when the main battery is powering the standby system

(At all other times, the auxiliary battery is isolated from the power distribution system)

page 6.20.8

77
Q

is battery charging automatically or manually controlled ?

A

automatically controlled

page 6.20.8

78
Q

what is the minimum time two fully charged battery can provide standby power for ?

A

60 min

page 6.20.8

79
Q

what is the batteries voltage range ?

A

22-30 volts

page 6.20.8

80
Q

what are the DC busses powered from the battery following a loss of both generators ?

A
  • battery bus
  • DC standby bus
  • hot battery bus
  • switched hot battery bus

page 6.20.8

81
Q

what is the difference between the Hot Battery Bus and the Switched Hot Battery Bus ?

A

the Hot Battery Bus is always connected to the battery and it is powered whenever the BATT is ON

the Switched Hot Battery Bus can be connected via a relay

page 6.20.8

82
Q

what is the purpose of the Battery Chargers ?

A

to restore and maintain the batteries at full electrical power

page 6.20.9

83
Q

what powers the main battery Charger ?

A

AC Ground Service Bus 2

page 6.20.9

84
Q

what powers the auxiliary battery Charger ?

A

AC Ground Service Bus 1

page 6.20.9

85
Q

how are the voltage during charging and after charging is completed ?

A

the battery chargers provide a voltage output tailored to maximize the battery charge.

Following completion of the primary charge cycle, the main battery charger reverts to a constant voltage TR mode.

page 6.20.8

86
Q

what is the particularity of the Battery Charger ?

A
  • it is also a Transformer-Rectifier
  • it powers the Battery Bus if TR3 fails

page 6.20.9

87
Q

if TR3 fails whatelse can take over the load and power the the Battery Bus ?

A

the Main Battery Charger TR

page 6.20.8

88
Q

during normal operation are the auxiliary battery charger and auxiliary batter isolated from the power distribution sistem ?

A

YES

page 6.20.8

89
Q

what type of power does the Standby System provide ?

A

115V AC and 24 V DC

page 6.20.11

90
Q

what are the components of the standby system ?

A
  • static inverter
  • AC standby bus
  • DC standby bus
  • battery bus
  • hot battery bus
  • switched hot battery bus
  • main battery
  • auxiliary battery

page 6.20.11

91
Q

what is the position of the Standby Power Switch and Battery Switch during normal operations ?

A

Standby Power Switch - AUTO

Battery Switch - ON

page 6.20.11

92
Q

under normal conditions what provides power to the AC Standby Bus ?

A

AC Transfer Bus 1

page 6.20.11

93
Q

under normal condition what provides power to the DC Standby Bus ?

A

TR1 and TR2/TR3

page 6.20.11

94
Q

under normal condition what provides power to the Battery Bus ?

A

TR 3

page 6.20.11

95
Q

what are the two main components of the Standby Power System ?

A
  • main battery
  • auxiliary battery

page 6.20.11

96
Q

when the Standby Power Switch is on AUTO what would cause the automatic switch from normal to alternate power ?

A

if power from either AC transfer bus 1 or DC bus 1 is lost

page 6.20.11

97
Q

what is the role of the Static Inverter ?

A

to convert 24 volt DC power from the battery to 115V AC power to supply the AC standby bus during the loss of normal electrical power

page 6.20.12

98
Q

what controls the power supply to the Static Inverter ?

A

the standby power switch and the battery switch on the overhead panel

page 6.20.12

B737 (8 decks)

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