Electrical

Question 0

What makes up the DC system

Answer 0

• 2 NiCd batteries
• 3 Transformer Rectifier Units (TRUs)
• 1 DC external input

Question 1

What makes up the AC system

Answer 1

• 2 IDGs
• 1 APU generator
• 1 Inverter
• 1 Ram Air Turbine (RAT)
• 1 AC external power unit

Question 2

What are the IDGs and APU generator rated at

Answer 2

40 kVa, 115 V, 400Hz, 3 phase

Question 3

What does the static inverter do

Answer 3

It converts 28v DC to 115v AC to power the STANDBY AC BUS when an AC power source is not available

Question 4

What type of power is produced by the RAT

Answer 4

15kVa, 115v AC, 400Hz, 3 phase

Question 5

When is the RAT automatically deployed

Answer 5

Whenever AC power sources are not powering AC buses

Question 6

How long after deployment will the RAT begin to supply power

Answer 6

8 sec

Question 7

Which bus does the RAT power when in use

Answer 7

AC ESS BUS

Question 8

During the timespan prior to RAT supplying power, what happens in order to maintain power

Answer 8

The batteries power the DC ESS BUS and the STANDBY AC BUS

Question 9

Which hydraulic pump does the RAT power

Answer 9

ACMP 3A

Question 10

Below what speed will the RAT be unable to continue to supply sufficient power

Answer 10

130kts

Question 11

What happens if airspeed drops below that required to utilize the RAT

Answer 11

The batteries power the DC ESS BUSSES and the STANDBY AC BUS through the static inverter

Question 12

What is a DC GPU used solely for

Answer 12

Powering the APU START BUS on the ground

Question 13

What are the TRUs rated to

Answer 13

300A

Question 14

What does TRU1 power

Answer 14

DC BUS1, DC ESS BUS1, DC GND SVC BUS, HOT BATT BUS 1, battery #1 charging

Question 15

What does TRU2 power

Answer 15

DC BUS 2, DC ESS BUS 2, HOT BATT BUS 2 and battery #2 charging

Question 16

What does the ESS TRU power

Answer 16

DC ESS BUS 3

Question 17

What kind of power do the batteries supply

Answer 17

22.8VDC, 27A

Question 18

When is the BATT 1 (2) OVERTEMP warning triggered

Answer 18

When the battery temp reaches 70C for 2 secs

Question 19

When do you use a DC GPU

Answer 19

When the battery is no longer available or the Battery #2 is below -20C

Question 20

What do the Integrated Control Centers (ICCs) do

Answer 20

Provide power distribution and protection for the airplane electrical loads, the secondary power distribution assemblies (SPDAs) and the circuit breakers

Question 21

How many ICCs does the plane have

Answer 21

4
• Left Integrated Control Center (LICC).

• Right Integrated Control Center (RICC).
• Emergency Integrated Control Center (EICC).
• Auxiliary Integrated Control Center (AICC).

Question 22

How are the circuit breakers classified

Answer 22

Thermal or electronic

Question 23

Where are the electronic CBs located

Answer 23

inside the SPDAs, in the electronics bays.

Question 24

Where are the thermal CBs located

Answer 24

In the cockpit and in the ICCsin the electronics bays

Question 25

What is the source priority order for powering the airplane

Answer 25

• Respective IDG.
• APU generator.
• GPU (on ground without APU).
• Opposite IDG.

If required the DC GPU can be used for the APU start

Question 26

What controls load shedding and when does it occur

Answer 26

The SPDAs shed load whenever electrical load increases beyond the system limit

Question 27

Which items are load shed

Answer 27

Galleys and right windshield heating

Question 28

What is the chain of electrical power

Answer 28

AC sources (IDGs, APU, external AC) -> electrical busses in the ICCs -> SPDAs -> individual components

Question 29

Which battery powers the APU starter

Answer 29

Batt 2

Question 30

What does the static inverter do

Answer 30

Converts 28v DC from the batteries to 115v AC to power the STANDBY AC BUS when an AC power source is not avail.