ELECTRICAL SYSTEM

Question 1

Sources of AC Power

Answer 1

• 2: Engine Generators
• 1: APU Generator
• 1: Ram Air Turbine (RAT)
• External Power
• Static Inverter

Question 2

Sources of DC Power

Answer 2

• 2 Batteries

- 3: TRU’s (TRU 1/2/ESS)

Question 3

GCU

Answer 3

• Generator Control Unit

Question 4

What do the GCU’s do?

Answer 4

• Control output of their respective generator
• Control the frequency and voltage of the GEN output
• Protect the network by controlling the associated (GLC)

Question 5

The output of an ENG GEN?

Answer 5

115-200V/400Hz/90KVA

3 - Phase

Question 6

The output of the APU GEN?

Answer 6

115-200V/400Hz/90KVA

3 - Phase

Question 7

The output of the RAT?

Answer 7

115-200/400Hz/5KVA

3 - Phase

Question 8

GAPCU

Answer 8

Ground and Auxilliary Power Unit

Question 9

What does a GAPCU do?

Answer 9

• Regulates, via the APU ECB, frequency and voltage of the APU GEN
• Protects the network by controlling the external power contactor and GLC

Question 10

Types of CB’s

Answer 10

• Green (Monitored)
• Black (Not-Monitored)
• Red Collared (WTB)

Question 11

How long until the DC BUS 2 supplies the DC BUS 1 and DC BAT BUS if the AC BUS 1 failed?

Answer 11

• Automatically after 5 seconds

Question 12

IDG

Answer 12

Integrated Drive Generator

Question 13

Electrical Priority

Answer 13

1. G - Generator (onside)
2. E - External Power
3. A - APU
4. R - RAT
5. B - Batteries

Question 14

BCL

Answer 14

Battery Charging Limiter

Question 15

Do battery contactors normally stay open or closed?

Answer 15

Open

Question 16

How do identify battery is on during preflight?

Answer 16

• BAT PB is Recessed
• LDG GEAR Down Lights ON
• Some cockpit lighting

Question 17

How long does it take for the RAT to power the EMER GEN?

Answer 17

8 seconds

Question 18

Min Speed for RAT

Answer 18

140 knots

Question 19

Describe how the EMER GEN obtains its power from the RAT

Answer 19

• RAT is automatically deployed within 8 seconds
• It pressurizes the Blue HYD SYS
• It then powers the hydraulic motor that power the EMER GEN

Question 20

Which generator normally has more load?

Answer 20

• GEN 1 due to AC BUS 1 powering AC ESS BUS

- Powers the DC BAT BUS through a BTC