A220 ELECTRICAL Questions with Detailed Verified Answers

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A220 ELECTRICAL Questions with Detailed
Verified Answers

Question: How many TRUs are there and how many Amps is each
Transformer Rectifier Unit (TRU) rated at?

Ans✅ ✅: 3 TRUs

TRU1: 350 Amps

TRU2: 350 Amps

TRU3: 225 Amps (additional 125 Amps dedicated to FBWPC)

Question: What do the TRUs do?

Ans✅ ✅: 3 TRUs are the primary source of DC power. They receive 115Vac and
convert it to 28Vdc and distribute to DC Buses.

Question: How many batteries do we have on the aircraft?

Ans✅ ✅: 2 NiCad Batteries

24Vdc and each rated at 42 ampere-hours

Question: Do you need batteries to start the APU?

Ans✅ ✅: Both batteries are needed for APU start if external power is not available.

BATT 1=APU ECU

BATT 2=APU Starter

Question: When will the BATT DISCHARGING caution message display
on the EICAS?

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Ans✅ ✅: When only the batteries supply power for more than 5 minutes

Also, a horn will sound until AC power is available or batteries are turned off.

Question: What DC buses do not show on the ELEC synoptic page?

Ans✅ ✅: BATT DIR 1

BATT DIR 2

DC EMER bus (only shows on ELEC synoptic page when not powered. (receives power
from both batteries)

Question: What are the 4 possible sources of AC power for the aircraft
(ground and flight)?

Ans✅ ✅: VFGs (L GEN and R GEN)

APU

EXTERNAL AC POWER

RAT

Question: What is the AC bus priority ?

Ans✅ ✅: AC BUS 1 = L GEN, EXT PWR, APU then R GEN

AC BUS 2 = R GEN, APU, EXT PWR then L GEN

Question: What is the maximum altitude for APU generator use?

Ans✅ ✅: 41,000'

Question: What is the maximum load on the AC generators?

Ans✅ ✅: 75kVA continuous

Question: What is available on the A220 to provice emergency AC
power?