Electrical

Question 1

AC power is provided by what sources?

Answer 1

Engine-driven generators
APU generator
External power

Question 2

DC power is provided by what sources?

Answer 2

Main battery
APU battery
TRUs

Question 3

What are the two subcomponents of the IDGs?

Answer 3

Constant Speed Drive (CSD)
40 kVA generator

Question 4

Once the IDG has been disconnected, can it be reconnected in the air?

Answer 4

No, only maintenance can reconnect

Question 5

What faults will cause the IDG switch light to illuminate?

Answer 5

Low oil pressure & high oil temperature (hot lop)

Question 6

The IDG will automatically disconnect with what two conditions?

Answer 6

Over torque & over temperature

Question 7

Generator fault protection is provided for what?

Answer 7

Under/over voltage
Under/over frequency
Out of phase

Question 8

With the external power on the aircraft, what will happen when an engine driven generator comes online?

Answer 8

The external power switch light changes from white IN USE to green AVAIL.
The engine-driven generator will then pick up the entire load.

Question 9

What is the purpose of the AC switch light on the external service panel?

Answer 9

Powers the AC Service Bus
Provides dome and lavatory lights
Electrical outlets in the cabin
Cleaning and maintenance switch light.

Question 10

When will the AC ESS XFER light be illuminated?

Answer 10

When the AC ESS BUS is being powered by BUS 2

Question 11

What is the power source priority for AC Bus 1?

Answer 11

GEN 1
APU GEN
GEN 2
EXTERNAL AC

Question 12

What would happen if a Bus fault condition were to occur on either AC Bus 1 or AC Bus 2?

Answer 12

The associated generator would be taken offline.

Question 13

Would the AC Bus be transferred to the next generator in line?

Answer 13

No, the AUTO XFER FAIL switch light will illuminate, preventing auto transfer.

Question 14

When will the ADG automatically deploy?

Answer 14

When any generator has been online.
AC Buses 1 and 2 become unpowered.
Weight off wheels.

Question 15

Once the ADG is deployed, what will it power?

Answer 15

AC ESS BUS.
Hydraulic pump 3B.
Slats and flaps.
Pitch trim channel 2.

Question 16

Below what speed will the ADG be unable to provide power?

Answer 16

135 kts.

Question 17

Why must you physically pull the ADG Handle to deploy, when doing the EMER POWER QRH?

Answer 17

To close the emergency tie contactors allowing the DC Essential Bus to remain powered by batteries after landing.

Question 18

Following ADG deployment, how can a generator be selected if it once again becomes operational?

Answer 18

By pushing the PWR TZFR OVERRIDE button.

Question 19

How many TRUs? Each is rated at how many amps?

Answer 19

Four at 120 amps.

Question 20

What do TRUs do?

Answer 20

They convert 115-volt AC power into 28-volt DC power.

Question 21

The APU battery is rated at ______ amps.

Answer 21

43

Question 22

The main battery is rated at ____ amps.

Answer 22

17

Question 23

How long can the batteries provide power in the event of total electrical failure?

Answer 23

30 minutes

Question 24

When will the main bus tie automatically close?

Answer 24

Anytime TRU 1 or 2 fails

Question 25

What happens automatically anytime the DC main tie closes?

Answer 25

DC Utility Bus is shed

Question 26

When will the DC EMER BUS be displayed on the synoptic page?

Answer 26

When one of the two sources of power for the Bus has a problem.

Question 27

What items are powered through the DC Emergency Bus?

Answer 27

Engine SOV APU SOV Hydraulic SOV Fire Extinguishing Circuits

Question 28

When does the DC essential tie automatically close?

Answer 28

Failure of essential TRU 1 or essential TRU 2

Question 29

What is the purpose of the essential TRU 2 transfer contactor?

Answer 29

To allow ESS TRU 2 to be powered by the ESS AC BUS.