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Flashcards in Electrical Deck (79):
1

The AC system is comprised of:

Two IDG's
One APU
One Inverter
One Ram Air Turbine - RAT
One AC external power unit

2

The DC system is comprised of:

Two NiCd batteries
Three TRUs - Transformer Rectifier Units
One DC external power unit

3

On the AC Electric Panel, the IDG 1/2 switch in the OFF position does what?

Opens the IDG contactor isolating the IDG from the respective AC Bus

4

How long must one hold the IDG 1/2 in the DISC positon

Must be held in this position for one second to mechanically disconnect the IDG

5

What does the AC BUS TIES switch do in the 1 OPEN position?

Opens the Bus Tie Contactor - BTC 1 - segregating AC BUS 1 from AC BUS 2

6

BATTERY 2 supplies power to ... ?

HOT BATT BUS 2

7

In the ON position, BATT 1 is connected to.. ?

the DC ESS BUS 1

8

BATTERY icons in GREEN

Battery voltages greater than 18 V

9

BATTERY icons in WHITE

Battery voltages less than 18 V

10

What is the meaning of IDG 1/2 OIL EICAS Msg?

IDG pressure drops below 140 psi
or
IDG oil temperature reaches 168 deg C

11

Do not hold the IDG 1/2 knob in the DISC position for longer than.. ?

3 seconds

12

The IDG will automatically disconnect when... ?

when manual disconnection is not performed with the oil temperature reaching 185.6 deg C

13

Pushing the AC GPU button connects...

The external power to the AC BUS TIE

14

The RAT - Ram Air Turbine produces... ?

15 kVa, 115 V AC, 400 Hz

15

The RAT is deployed whenever... ?

AC power sources are not powering AC buses

16

How long does it take for the RAT to supply power to the AC ESS BUS

8 seconds

17

What does the RAT power?

supplies power to the AC ESS BUS

18

If it takes 8 seconds for the RAT to power the AC ESS BUS, what is the design to prevent total loss of power?

The RAT powers the AC ESS BUS which powers the ESS TRU which powers DC ESS BUSES. To avoid total loss of power for the 8 seconds it takes to power, dedicated standby battery is used as backup power to the DC ESS BUSES and the STANDBY AC BUS

19

How are primary flight control tasks maintained in the event of loss of electrical power?

RAT drives the ACMP 3A

20

What is NBPT

No Break Power Transfer

21

What does the NBPT do?

The No Break Power Transfer allows the momentary paralleling between two AC power sources: The IDG's, GPU and APU generator in any combination

22

On the DC Power Panel, what does the DC BUS TIES toggle switch do

Opens both essential tie contactors and a DC tie contactor

23

The RAT powers what?

AC ESS BUS when AC bus 1 and 2 are not powered

24

What is the minimum battery voltage

22.5 Volts without action
below that and the battery needs to be warmed up per the SOPM
21.0 limit below which maintenance needs to be called out.

25

Generators are rated to

40 KVA

26

the RAT generator is rated to...

15kVa

27

How long does it take the RAT to power the AC ESS BUS

8 seconds

28

When is the RAT deployed

When both AC Bus 1 and 2 are not powered

29

The LED light next to the IDG switches indicate what?

Which IDG needs to be disconnected due to a drop in oil pressure below 25 psi and / or a oil temperature reaches 168 deg C

30

Automatic IDG disconnect happens when the oil temperature reaches ...

186 deg C

31

During APU start what happens?

BATT 2 is isolated from the network and used to power the APU START BUS exclusively

32

The RAT drives which ACMP for primary flight control tasks?

Hydraulic Pump 3A

33

When is the NBPT active

On the ground during power transfers

34

What do the batteries power during the 8 second delay while the RAT is being deployed

DC ESS BUS
and
STANDBY AC BUS through the static inverter

35

What do the TRUs do?

convert AC power from the AC BUSES into DC power

36

What is the min battery temp for APU start?

-20 deg C

37

If the RAT fails, how long will the battery power be able to provide for essential systems

10 minutes

38

When will the EICAS message BATT 1/2 OVERTEMP be displayed

Battery temperature reaches 70 deg C for min of 2 seconds

39

When would you use DC GPU?

Battery unavailable
or
Battery 2 temp less than -20 deg C

40

What systems are on the AC ESS BUS

AC fuel pump 2
Hydraulic Pump 3A
1 Slat Channel
1 Flap Channel

41

When the aC bus tie selector knob is selected to the OPEN position, what happens

The selected BUS TIE CONTACTER - BTC is opened, segregating the AC BUS 1/2 from the opposite AC BUS 1/2

42

What is required before the "AVAIL" light on the GPU button illuminates?

Correct Volts / Amps / Frequency

43

What happens when the TRU ESS toggle switch is placed in the off position

Isolates the TRU ESS BUS from DC ESS BUS 3

44

On the ground, what happens when the aircraft is powered only by battery power for longer than 5 minutes

A horn will go off to notify ground personel

45

What happens when TRU 1 /2 toggle switch is placed in the off position?

Isolates TRU 1 /2 from DC ESS BUS 1 / 2

46

Why does Battery 2 have an "AUTO" position?

To allow the automatic operation of BATT 2 such as for APU start and BATT 2 being used exclusively for APU Start

47

What happens when the DC BUS TIES toggle switch is placed in the OFF position?

opens both essential tie contactors and a DC tie contactor

48

In the OFF position, BATT 1 is connected to what?

The HOT BATT BUS 1 is powered by BATT 1

49

On the Electrical Synoptic page, what does a green / white battery symbol indicate

Green indicates BATT voltage greater than 18 V
White indicates voltage less than 18 V

50

Pushing the AC GPU button connects what?

The external power to the AC BUS TIE

51

What does the Static Inverter do?

converts 28 V DC from the batteries to 115 V AC to supply the STANDBY AC BUS when AC power source is not available. (double check... but the igniters are on this bus)

52

DC ESS BUSSES are powered through what?

the ESS TRU

53

What minimum speed is required for the RAT to provide electrical power?

130 KTS

54

The RAT provides power to what?

The AC ESS BUS

55

What kind of power does the RAT provide

AC power

56

How does the RA, if it is AC power, provide power to the DC BUSSES?

DC ESS BUSSES are powered through the ESS TRU

57

What happens below 130 KTS with the RAT deployed

Load shedding occurs. The DC ESS BUS and the STANDBY AC BUS are powered through the static inverter from the batteries.

58

What do the TRUs do

Convert 115 V AC power to 28 V DC

59

When the DC GPU is connected, what is powering the APU START BUS?

The DC GPU powers the APU START BUS, not BATT 2 as is normal condition

60

What BUS is powered by the RAT

AC ESS BUS

61

What is the altitude limit for the RAT

There is no altitude limit

62

How many TRUs are there?

3 TRUs

63

What is the ICC

Integrated Control Center

64

How many ICCs are there?

There are 4 ICC - Integrated Control Center
Left - LICC
Right - RICC
Emergency - EICC
Auxiliary - AICC

65

What is the purpose of the Integrated Control Center?

provides power distribution and protection for electrical loads

66

What is the SPDA

Secondary Power Distribution Assemblies

67

How are electrical loads and distribution loads monitored and protected?

Through the ICC's, SPDA's and Circuit Breaker Panels

68

What kind of circuit breakers are there?

Thermal and Electronic

69

What provides for the distribution and control of electrical power?

The ICCs - Integrated Control Center and the SPDAs - Secondary Power Distribution Assemblies

70

What does each ICC incorporate?

Thermal Circuit Brakers
Line Replaceable Units
Line Replaceable Modules
AD/DC Busses

71

The AC / DC busses are located where?

Inside their respective ICC - Integrated Control Center

72

What is the purpose of the SPDA - Secondary Power Distribution Assembly?

Receives power from the ICC and electrical busses and distributes it according to system logic.

73

The SPDA replaces what found in older aircraft?

Thermal Circuit Breakers and Electromechanical Relays

74

Where are the thermal CBs located?

Flight Deck side wall and other inside the ICCs in the electronics bay

75

Where are the electronic CBs located?

Inside the SPDAs in the electronics bays

76

Can the remote ICC remote CBs be reset?

Only by a mechanic

77

Can the SPDA remote electronic CBs be reset?

Yes, via the MCDU

78

Explain the flow of electrical power

The electrical power generated from the IDG, APU or GPU is directed to the ICCs and the electrical busses. From their it is routed through the SPDA and to the electrical systems.
The systems requiring complex logic are connected to the MAUs.

79

Mostly complete...

Just some in depth emergency power question to go