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ATR type Rating > Skyblue CBT electrical system > Flashcards

Skyblue CBT electrical system Flashcards

1
Q

what does the electrical system consist of?

A
  • main battery
  • emergency battery
  • 2 engine driven DC starter generators

-2 AC wild generators

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2
Q

what do the static inverters do?

A

convert DC power to AC power at a constant frequency

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3
Q

what do the static inverters power?

A

the respective AC bus

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4
Q

what does the TRU do?

A

converts 115V AC from the AC wild gens to 28v DC in order to power the DC electrical system

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5
Q

what does the bus tie contactor do?

A

connects the tight and left electrical networks in the event of a failure

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6
Q

What page on the MFD shows the ACW system?

A

ACW/hydraulic page

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7
Q

what controls the AC and DC system logic?

A

2 Bus power control units (BPCU’s)

one for AC and one for DC

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8
Q

How does the BPCU control the electrical systems config?

A
  • ACW BUS TIE contactors
  • DC BUS TIE contactors
  • load shedding through utility bus contactors
  • AC and DC EXTERNAL power contactors
  • ACW service bus contactor
  • DC service bus contactor
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9
Q

what usually powers the DC system?

A

2 engine driven generators or external power

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10
Q

what is the purpose of the battery?

A

to power DC when not connected to ground power or with engines not running

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11
Q

what buses make up the DC system?

A

DC BUS 1

DC BUS 2

DC STBY BUS

DC EMER BUS

DC ESS BUS

HOT MAIN BAT BUS

HOT MAIN EMER BUS

UTIL BUS 1

UTIL BUS 2

GND HDLG BUS

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12
Q

What usually powers DC buses 1 and 2?

A

their respective starter generator

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13
Q

what powers the DC STBY BUS?

A

BUS 1 via the HOT EMER BATT BUS and DC EMER BUS

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14
Q

what happens if one of the batteries has a thermal runaway?

A

battery charge contactor will openand associated systems will be transferred to DC BUS 1

If BUS 1 is not powered, then a bus transfer contactor will close which will cause the associated bus to be powered by DC BUS 2

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15
Q

what powers the DC EMER BUS and DC standby buses if BUS 1 is offline?

A

ACW via the TRU

if the TRU is not running then power is from the HOT EMER BATT bus

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16
Q

what normally powers the DC ESS BUS?

A

DC BUS 2 via the HOT MAIN BATT BUS

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17
Q

What powers the ESS BUS if the battery has a thermal runaway?

A

DC BUS 1

or DC BUS 2 through the main bus transfer contactor

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18
Q

what powers non essential loads in the DC system?

A

2 utility buses

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19
Q

what powers the utility buses?

A

their respective DC bus through a utility bus contactor

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20
Q

what controls the utility bus contactors?

A

BPCU

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21
Q

when are the utility buses automatically shed by the BPCU?

A

when there is an overload of the DC system

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22
Q

how many volts are the MAIN and EMER batteries?

A

24v

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23
Q

how many amp hours are the 2 batteries rated for?

A

MAIN: 43

EMER: 17

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24
Q

what are the functions of the main battery?

A

engine starting and emergency power

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25
Q

what are the functions of the emergency battery?

A

ensures that emergency electrical network is powered even if main battery is depleted

prevents power transients on critical equipment during engine starts

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26
Q

what does the MFC do for the batteries (3)

A
  1. monitors battery charge
  2. connects the battery to DC BUS for charging
  3. PREVENTS THERMAL RUNAWAY
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27
Q

when are the HOT buses operating?

A

whenever the associated battery is charged

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28
Q

what powers the HOT buses under normal conditions?

A

DC BUS 1 and DC BUS 2

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29
Q

how is battery voltage and current checked?

A

maintenance panel on captains side

info is read from associated hot battery bus

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30
Q

what connects the ground handling bus to the HOT MAIN BATT BUS?

A

BATTERY TRANSFER UNIT (BXR)

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31
Q

when will the battery transfer unit (BXR) close?

A
  • cargo door operating panel opened
  • refueling panel access door is opened
  • entry door is opened
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32
Q

how is the ground handling bus powered with external power?

A

BXR is opened and the external ground handling relay (EGHR) is closed which powers the ground handling bus through the DC service bus providing the DC GND SVCE bus is selcetd on from the cabin crew panel

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33
Q

what does the GND HDLG BUS power?

A
  • cargo door control and indicators
  • fueling control and indicators
  • entrance light
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34
Q

what does the DC service bus power?

A
  • Galley
  • aircraft lighting
  • lavatory system
  • auto feather pump manual control
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35
Q

what powers the DC service bus?

A

DC bus 1 or external power

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36
Q

where do we connect the dc service bus to external power?

A

the DC button on the flight attendant panel if external power is connected

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37
Q

how is the service bus connected to external power?

A

DC servcie bus relay

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38
Q

how is the DC service and utility bus powered if its connected to BUS 1?

A

DC SVCE/UTLY BUS button on cockpit overhead panel

this overrides the cabin button

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39
Q

if the battery toggle switch is on in basic mode, what does the main battery supply?

A
  • hot main battery bus
  • DC essential bus

DC STBY BUS

Inverter 1

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40
Q

in basic mode, what does the HOT EMER BATT bus power?

A

DC EMER BUS

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41
Q

how is bus 2 powered when connected to external power?

A

through the bus tie contactor (BTC)

42
Q

how is power for the inverter 1 transferred from the hot main batt bus to bus 1 when bus 1 is energised?

A

static power override contactor closes and hot main battery transfer contactor opens

43
Q

what do the BAT CHG buttons allow?

A

charging of the batteries through external power

44
Q

how does the power source for the DC STBY BUS change when connected to external power?

A

standby bus transfer contactor takes power from the HOT EMER BATT BUS instead of the HOT MAIN BAT BUS`

45
Q

what happens when DC BUS 1 is powered by a generator and external power is disconnected?

A
  • service select bus relay closes and service bus transfer relay opens

this transfers the source from external power to DC bus 1

46
Q

what drives the DC generators?

A

associated engine accessory gearbox

47
Q

what voltage does the DC GEN provide?

A

27-31 volts with a nominal output of 30

48
Q

what is the nominal power output of the DC GEN?

A

12 KW

49
Q

how are the DC generators cooled?

A

air cooled

50
Q

what does the start contactor do?

A

connects the generator to the battery, dc external power of the opposite generator during engine start

51
Q

what do the battery charge contactors do during start?

A

isolate the batteries from their respective buses in order to prevent power transients during start

52
Q

what powers the DC stby bus during start?

A

hot emer battery bus

53
Q

what powers inverter 1 during start?

A

hot main batt bus

54
Q

during a cross start, when will the starter bus connect to the opposite side generator?

A

10% NH

55
Q

when does the starter genratro stop cranking the engine during a cross start?

A

45% NH

56
Q

when during start does the starter generator act as a generator?

A

61.5% NH

57
Q

what controls the transition from starter generator to generator during start?

A

generator control unit (GCU)

58
Q

what does the GCU do during start transition from Starter gen to generator?

A

opens start contactor at 45% NH

closes genrator contactor at 61.5% NH

59
Q

what 8 issues does the GCU provide fault protection and detection for?

A
  • over or under voltage
  • over or under speed
  • differential fault current
  • generator overload
  • power and fault current limiting
  • bus tie lockout
  • reverse current
  • equalising load
60
Q

how does 1 generator power both sides of the system?

A

by going through the closed bus tie contactor

61
Q

when will the bus tie contactor automatically open?

A

when both generators are online after start

62
Q

what does the AC system consist of?

A

a 26v network

a 115v network

2 inverters

63
Q

what DC voltage do the static inverters require to operate effectively?

A

18-31 DC

64
Q

what frequency does the AC system work in?

A

400hz single phase

65
Q

what does AC bus 1 115V power?

A
  • electrical power
  • indicating and recording
  • navigation
  • pneumatic
66
Q

what does AC STBY BUS 115V power?

A
  • fire detection
  • ice and rain protection
  • indicating and recording
  • lights
67
Q

what does AC BUS 2 115V power?

A
  • air conditioning
  • electrical power
  • indicating and recording
  • lights
  • navigation
68
Q

what does AC BUS 1 26V power?

A

flight controls

navigation

69
Q

what does AC STBY BUS 26V power?

A

flight controls

indicating and recording

navigation

70
Q

what does ac bus 2 26v power?

A

naviagtion

71
Q

what will happen automatically in the event of an inverter failure?

A

AC BUS TIE relay closes and links the 2 115V AC buses`

72
Q

what happens in the event of an inverter 1 failure?

A

AC STBY BUS automatically switvhes over to be powered by AC BUS 2

73
Q

what powers the AC wild system?

A

2 engine driven brushless ACW generators

74
Q

what is the delivery voltage of the ACW system

A

20 KVA

75
Q

what is the power range of the ACW system?

A

115-200V

76
Q

what is the frequency range of the ACW system?

A

341-488Hz

77
Q

what does the ACW GCU provide protection and detection for? (9)

A
  • overvoltage
  • undervoltage
  • power and fault current limiting
  • bus tie lockout
  • differential fault protection
  • over frequency
  • under frequency
  • open phase
  • voltage regulation
78
Q

when will the ACW GCU open a contactor?

A

when a fault has been detected

79
Q

how are the 2 ACW buses connected in the event of an ACW gen failure?

A

2 contactors are closed linking the 2 buses to be powered by the remaining ACW GEN

80
Q

how is external power connected to the ACW system?

A

EXT power button on overhead ACW panel

ground power will now take priority over the ACW generators and their connectors will be opened

81
Q

what powers the ACW service bus?

A

ACW BUS 1 or external power (pushbutton to connect in cabin)

82
Q

when is the ACW service bus shed?

A

when one ACW generator is offline

83
Q

in the event of a double DC generator failure, what will the TRU power using the ACW system?

A
  • DC STBY BUS
  • DC EMER BUS
  • DC ESS BUS

INV 1

84
Q

what will the DC generator do if it senses an underspeed condition?

A

BTC will close, and the generator will reconnect itself automatically once its back up to speed

(if any other GEN fault occurs we need to reset manually)

85
Q

when will a SHED CAPTION and caution bell sound?

A

when an overload is sensed. at least one utility bus will then be isolated

86
Q

when will the MFC open the battery charge contactors?

A
  • thermal runaway
  • if associated dc bus voltgae is less than 25v
  • if batter toggle swtich is in overide
  • during engine start
87
Q

when will MFC close battery charge contactors during start?

A

when start selector is out of the start or crank position

88
Q

when will a FAULT show on the battery charge push button?

A

if an overheat is sensed (150C)

if the charge contactor fails do operate

89
Q

what happens if battery toggle swtich is on when connected to external power or the genrators?

A

HOT EMER BUS powers:

  • DC EMER BUS
  • DC STBY BUS

HOT MAIN BAT BUS powers:

  • DC ESS BUS
90
Q

WHAT ARE THE only powered buses with no connected power and the battery toggle switch off?

A

HOT EMER BATT BUS

HOT MAIN BAT BUS

91
Q

what does the override toggle switch position do?

A

keeps the DC system in basic mode in the event of double DC failure

92
Q

when does the undervoltage caption on the stby bus button illuminate?

A

DC STBY BUS voltage less than 19.5V

93
Q

what happens when the STBY BUS override button is pushed?

A

DC STBY BUS and inverter 1 are powered by the source that is powering the DC EMER BUS

94
Q

what happens when the STBY BUS override button is pushed in order to release?

A

DC STBY BUS and INV 1 will be powered by the source that powers the DC essential bus

95
Q

what does turning the TRU button do?

A

TRU draws power from ACW BUS 2 and provides DC to:

  • DC EMER BUS
  • DC ESS BUS
  • DC STBY BUS
  • INV 1
96
Q

when will an inverter fault happen?

A

undervoltage or overvoltage (less than 102 or greater than 123)

97
Q

what powers the inverter 1 when override is in the normal position?

A

the same source what is powering the DC ESS BUS

INV 1 will also power the AC STBY BUS

98
Q

what powers INV 1 when the override button is pressed?

A

the same source as what is powering the DC EMER BUS

INV 1 will also power the AC STBY BUS

99
Q

what voltage does inverter 1 require for normal operation?

A

18 volts

100
Q

when will an ACW generator reset itself automatically?

A

after an NP overspeed of 3 seconds or less

generator underspeed

101
Q

what does he ACW BTC operating selector on the captains side allow?

A

maintenance to force open the ACW BTC

102
Q

at what voltage will the emergency bus box on the elec page go amber?

A

18v

ATR type Rating (22 decks)

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