Electrical

Question 1

Min Speed to run RAT

Answer 1

140 kts

Question 2

Description of Electrical System

Answer 2

• three-phase 115/200 V 400 Hz AC
• 28 V DC

AC:

• 2 engine generators
• 1 APU generator
• 2 Generators Control Units (GCU)
• static inverter transforms DC to AC power
• emergency generator

DC:

• 2 Transformer Rectifiers (TRs)
• 2 main batteries (23 ah)

Question 3

Output rating of Engine and APU generators

Answer 3

• 90 KVA of three phase
• 115/200 V
• 400 Hz

Question 4

Description of Emergency Generator

Answer 4

• 5 KVA of three-phase
• 115 and 200 V
• 400 Hz
• driven by blue hydraulic if all main gens fail

Question 5

Describe the static inverter

Answer 5

transforms DC power from Battery 1 into AC power

• 1 KVA of single-phase
• 115 V
• 400 Hz AC

Question 6

Transformer Rectifiers (TRs)

Answer 6

TR1 and TR2 supply 200 A of DC power

ESS TR supplies 200 A DC to ESS DC from emergency gen

Question 7

How many types of circuit breakers?

Answer 7

Two

• monitored (green)
• non-monitored (black)

Question 8

Generator Priority

Answer 8

• Main Gens
• GPU
• APU

Question 9

When does RAT automatically extend?

Answer 9

• Above 100 kts with loss of AC Bus 1 and AC Bus 2

- couples after 8 secs

Question 10

What busses are supplied during ELEC EMERG

Answer 10

Emergency Generator supplies:

AC ESS BUS, and the
DC ESS BUS via the ESS TR

Question 11

When are the batteries connected to the DC BAT BUS?

Answer 11

• APU starting
• Battery voltage below 26.5 V (batt charging)
• Loss of AC BUS 1 and 2 when below 100 kt (EMER GEN not supplying)

Question 12

How to determine remains battery life?

Answer 12

Total load (in amps) of operating electrical components / battery amp hr rating

Question 13

Components and function of IDGs

Answer 13

Integrated Drive Generators include:

• constant speed drive unit (CSD)
• generator
• CSD is link between engine and generator to provide constant generator drive of 12000 RPM regardless of engine speed*

Question 14

What do the Batteries power on the ground?

Answer 14

Below 50 knts: static inverter, DC BATT Bus, DC ESS Bus, Hot Bus 1, Hot Bus 2

In Normal config batteries are disconnected most of the time.

Used to start APU with batt voltage above 25.5V
*APU must be started within 30 mins of selecting Batts to Auto

Question 15

What items are on Hot Batt Bus

Answer 15

• clock
• APU Fire Extinguishing
• Eng 1 and 2 Fire Extinguishing
• RAT Auto Control
• ELAC 1 and 2
• SEC 1
• Pitch Trim
• APU Fuel Pump

Question 16

What items are on Batt Bus

Answer 16

• APU auto fire extinguishing
• APU starting
• FWD and AFT Cargo Bottles