ATA 24 Electrical Systems Flashcards

1
Q

The BUS TIE relay will open when?

A

1) The AMC detects a different current value between the main BUSES
2) The Main Voltage drops below 12V
3) GEN1 or GEN2’s current difference is more than 75A

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2
Q

The BUS TIE relay will close when?

A

1) BATT MASTR switch to ENGAGE
2) BUS TIE SWITCH ON
3) Switch engine ON

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3
Q

With 2 Generators on, which BUSes are live?

A

ALL BUSES

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4
Q

With 1 generator offline, what BUS is offline?

A

The NON-ESS BUS

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5
Q

With 2 Generators offline, what BUS is offline

A

SHED BUS & NON-ESS BUS

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6
Q

The battery box contains what?

A

BAT HOT BUS, BR, EPR and BAT BUSS

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7
Q

The BAT BUS is connected to what?

A

The DIODE BOX 1&2 and the BUS TIE relays

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8
Q

The ESS BUS & AMC BUS take power from where?

A

The BAT BUS through the DIODE BOX

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9
Q

DIODE BOX 1&2 have power coming in from where?

A

The BAT BUS and MAIN BUS 1&2

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10
Q

Where are the BUS TIE’s located?

A

In the DISTRIBUTION BOXES

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11
Q

The EMERGENCY BATTERY is charged from where?

A

All 3 sources - The MAIN BAT, GENERATORS or EPU

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12
Q

Who has command, the BATTERY or the EPU?

A

The EPU through the control box.

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13
Q

The electrical system operates at what Voltage?

A

28.5V

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14
Q

The electrical system is designed to what principle?

A

A Duplex Parallel generation and seperation system.

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15
Q

What Voltage supply is the battery?

A

24V

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16
Q

If both generators and the main battery fail, what supplies the power?

A

The emergency battery to the emergency equipment.

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17
Q

What is acting as the return conductor for some electrical sub-systems?

A

The airframe

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18
Q

The electrical supply system consists of how many systems?

A

Four.
➢ Starter/generator system
➢Battery system
➢Emergency power supply system
➢External power supply system

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19
Q

Where are the AMC’s installed?

A

in the avionic bay below the cockpit floor

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20
Q

What WARNINGS can you have on the electrical system?

A

BATT OVERTEMP only

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21
Q

What is the BATT overtemp trigger?

A

71C inside the battery casing.

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22
Q

What is responsible for the power generation control and protection circuits?

A

The Generator Control Units (GCU)

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23
Q

What are the current sesnors connected to?

A

GCU’s & AMC’s to measure current from the generators, battery and EPU

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24
Q

What RPM do the starter windings de-energise?

A

61% N1

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25
Q

How many brushes are in the generator?

A

Four

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26
Q

What output do the generators produce?

A

200A by 26-30V

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27
Q

Where is the TEMP SWITCH located for the generators?

A

On the mounting flange

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28
Q

What controls the starter gen relays?

A

The GCU

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29
Q

How is the GCU powered?

A

by the respective GEN or, backup power is via the ESS BUS

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30
Q

What voltage is an OVERVOLTAGE from the GEN?

A

exceeding 31.5V

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31
Q

What is an UNDERVOLTAGE?

A

below 20V

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32
Q

What is an OVERCURRENT?

A

230A

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33
Q

What is a REVERSE CURRENT?

A

a reverse current in the circuit.

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34
Q

What is a FEEDER FAULT?

A

when the current difference between two current sensors (CS1&CS2) is higher than 110 +-11 A

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35
Q

What is an Anti-Cycle protection

A

allows the pilot only one resest of the generator if the fault stays.

36
Q

How many protection functions do the GCU’s provide?

A

6

37
Q

The point of regulation (POR) setting is set by what?

A

pin-coding at the GCU connector

38
Q

How does the GCU regulate the POR voltage?

A

by Pulse Width Modulation (PWM)

39
Q

What ARINC does the HELIONX use?

A

ARINC 429

40
Q

The GEN switches have how many positions?

A
  1. OFF, NORM, RESET
41
Q

What does the GEN RESEST switch do?

A

Resest the respective GCU to reactivate the generator

42
Q

What is the capabilty of the generator relays?

A

400 A

43
Q

The status of the electrical system is displayed and monitored by what?

A

The HELIONIX system.

44
Q

What triggers a Low voltage warning?

A

21V

45
Q

What triggers a Low voltage caution?

A

24V

46
Q

What triggers a high voltage caution?

A

29.5V or higher

47
Q

What triggers a high voltage warning?

A

31V or higher

48
Q

Where can the BUS voltage be adjusted?

A

the settings and tuning page.

49
Q

How much can the BUS voltage be adjusted by?

A

+-1.9V

50
Q

Where is the current for each generator measured?

A

Current Sensor 1 (CS1)

51
Q

What is a high current caution?

A

200A

52
Q

When will a high current caution turn into a warning?

A

after 2minutes above 200A, or 5s above 300A

53
Q

What is a white generator symbol?

A

OFF / NOT CONNECTED

54
Q

What is a green generator symbol?

A

ON / CONNECTED

55
Q

What is a amber generator symbol?

A

ABNORMAL CONDITION STATE

56
Q

If the generators are online, what will the battery current be?

A

a minus figure as it’s charging.

57
Q

What is GEN OVHT TEMP?

A

178C

58
Q

Where is the GEN TEMP SENSOR located?

A

In the mounting flange for the generator, monitoring the temp at the air outlet

59
Q

What is a GEN DISC SENSOR advisory?

A

if the continuity check of the discrete signal for GEN DISCONNECT fails during the power up test.

60
Q

What does the battery backup relay do?

A

connects the battery to the BUS TIE and warning unit

61
Q

What is the voltage & capacity of the battery?

A

24V & 40Ah (optional 44Ah)

62
Q

Where is the battery temp switch?

A

Inside the battery housing

63
Q

How long can the battery provide power in an emergency situation?

A

30 mins

64
Q

What temp does the BATT OVHT trigger?

A

71C

65
Q

How can the battery be charged?

A

By the generators only

66
Q

The battery switch has how many positions?

A

Three. OFF, NORM, ENGAGE

67
Q

What happens when the battery is switched to ON?

A

The battery backup relay energises, powers the battery bus which then sends power through the diode box to the ESS & AMC BUS.

68
Q

What happens when the battery master switch is set to engage?

A

The BUS TIE RELAYS are engaged and the self-locking loop keeps the BUS TIES closed. The master battery switch springs back to ON.

69
Q

If the battery is set to OFF with the generators egaged, will it charge?

A

No

70
Q

Which has priorty, the EPU relay or battery?

A

EPU via the control relay

71
Q

Where is the battery back up relay located?

A

R/H cable channel.

72
Q

When does BATT DISCHARGING appear?

A

when battery current is above 5 A for 3 mins, or 5A & less than 24.5V

73
Q

What current trigger ELEC OVERLIMIT caution?

A

above 125A

74
Q

Which BUS is the EMERGENCY POWER SUPPLY charged from?

A

ESS BUS 2

75
Q

What does the EMERGENCY BUS power?

A

the IESI and the emergency lights

76
Q

What is the OUPUT Voltage of the STNDBY BATTERY?

A

24.5V

77
Q

Which pin of the EPU activates the EP control relay?

A

The short pin.

78
Q

What does the external power control relay do?

A

provides a ground signal to energize the external power relay or battery relay.

79
Q

What is the function of the external power interlock relays?

A

to disconnect the generators during ground operation

80
Q

Where is the EPU current measured?

A

The same hall-effect current sensor as for the main battery current

81
Q

Where are all the BUS BARS located?

A

in the junction and distribution boxes, the service connector panels and
the overhead panel.

82
Q

When would the self-locking loop be opened?

A

in the case of an abnormal condition, causing the BUS TIES to OPEN

83
Q

What happens if the MAIN BUS short circuit protection detects voltage below 12 VDC?

A

The short circuit protection opens the self-locking circuit, causing the BUS TIE relays to open. The AMC can also trigger it if there’s a current difference or limit exceeded.

84
Q

What are the lower priority electrical systems connected to?

A

The SHED BUS and NON-ESS BUS.

85
Q

What load are the SHED BUSES consumers?

A

normal load

86
Q

Non-ESS bus is for what consumers?

A

High load and maintenance equipment.

87
Q

Where are the AMC buses located?

A

With the NON ESS bus in the service connector panel