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Flashcards in Electrical Deck (50)
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1

TRU ESS switch

In off position isolates TRU ESS from ESS Bus three

2

DC BUS TIE switch

Opens DC TIE contacter and both ESS TIE contacters when in the off position

3

BATT ONE selector knob

On: Connects batt one to DC ESS Bus one

OFF: supplies power to hot batt bus one only

4

IDG EICAS Messages

Output always displayed even if zero.
If output is out of range or is invalid digits are then replaced by three amber dashes.

5

IDG EICAS ICON indications

Green: IDG is available and knob in auto position
White: IDG is available and selecter knob in off position or engine not running.
Amber Dash: invalid information

6

AC GCU Icon indications

Green: GPU connected and GPU button pushed in
White: GPU connected and button is pushed out.
Amber Dashed: invalid information

7

Components of AC System

Two IDGs
APU
One inverter
One RAT
ONE AC External power unit

8

IDG Switches

Auto: allows automatic operation of the electrical system.

Off: opens the contacter and isolates the IDG from the perspective AC bus.

Disc: must be held in this position for IDG to disconnect.

9

APU Switch

Push in, allows automatic operation

Push out, opens and isolates APU from the AC BUS TIE

10

AC BUS TIES knob

1 or 2 OPEN,,, opens the bus tie contactor segregating the selected side from the other side.

AUTO,,,,, Allows the system operational logic to control the system automatically.

11

GPU Button

Push in,,,, connects AC GPU to system according to source priority.
Pushed out, isolates GPU from system..

AVAIL,,,, indicates GPU is avail with proper voltage, amps and frequency

IN USE, GPU is powering system.

12

BATT EICAS ICONS

Green,,,,, Voltage is greater than 18V
White, less than 18 V
Dashed Amber,,,,, invalid information or value is out of range.

Batt icons always displayed

13

APU START BATT

Batt 2 is isolated to power the APU start bus.

14

What must be done with GPU push button after each use once APU takes over?

Us the pushed out even if the IN USE light is out. This must be done for the next connection to work.

15

Inverter

Converts 28 volt DC from the batteries to 115 Volts AC to supply the STANDBY AC BUS when an AC power source is not available.

16

RAT rating

15 kVA 115 volts AC 400 Hz three-phase

17

Number and type of batteries

Two nickel cadmium

18

Number or TRUs

3 transformer re citified units convert AC to DC.

19

What distributes electrical power?

Four integrated control centers,,,, ICCs and two secondary power distribution assemblies,,,,, SPDAs

20

Function of constant speed drives?

Convert variable engine speeds into constant generator speed.

21

Power output of IDG?

40 kila volt amp, 115 volt, 400 hertz three phase

22

What is a GCU?

Generator control units... They monitor and control the IDGs

23

What is the fail safe disconnect for IDG?

Input shear shaft and thermal disconnect operation.

24

What EICAS message is displayed if loss of electrical power and RAT fails to deploy?

BATT DISCHARGING warning message.

25

Inverter operation

Converts 28 VDC to 115 VAC 400 Hz frequency stabilized single phase when only battery is providing power.

26

What is the main source of DC power when AC power is being used?

Three TRUs

27

Location of each TRU?

TRU ONE is in left integrated control center, TRU TWO is in right ICC and number three is in the emergency integrated control center.

28

TRU input and a output?

115 volts AC, 400 Hz frequency stabilized input converting that to 28VDC 300 AMPs

29

Location of batteries?

Number one in front eBay and two in aft eBay.

30

Do the batteries provide power to anything if BATT switches are off?

Yes, hot battery busses one and two.