Electrical

Question 1

If a breaker trips, what criteria should be used to determine whether or not to reset?

Answer 1

Reset once, only if the affected component is required for safe flight and landing (unless specifically directed by a QRH checklist procedure)

Question 2

A NBPT can occur between the APU Gen and what other electrical component?

Answer 2

Engine IDG

Question 3

How are BUS TIE isolation contactors controlled (RAXC / LAXC)?

Answer 3

By the isolation switches on the cockpit overhead panel, GCUs or BPCUs

Question 4

What is indicated by an amber OFF light in either GEN switch?

Answer 4

the IDG has been isolated by the GCU or the BPCU

Question 5

During normal operations (IDGs powering aircraft), the Ground Service Bus receives power from which bus?

Answer 5

Right Main DC Bus

Question 6

When does the Emergency Power System activate automatically in the ARM position?

Answer 6

ESS DC bus voltage drops too low, or after a 2.5G impact

Question 7

What buses are powered during HMG operation?

Answer 7

Both Standby AC Buses, Both ESS DC buses, ESS AC Bus

Question 8

Where does the E inverter receive power from?

Answer 8

Left or Right ESS DC Bus

Question 9

When is the AUX TRU capable of providing power to both the left and right ESS DC buses?

Answer 9

Standby Electrical Power (HMG)

Question 10

Where do the battery chargers receive their power inputs from?

Answer 10

L and R MAIN AC buses

Question 11

How many emergency batteries are installed on the airplane?

Answer 11

4

LEER, REER and AEER

Question 12

How are the emergency batteries charged?

Answer 12

Left = Left standby AC bus
Right = Right standby AC bus
Forward lighting = Left main AC bus
Aft lighting = Right main AC bus

Question 13

When do the E-Batts come on in armed position?

Answer 13

Less than 20V DC

Question 14

Minimum battery voltage for APU start?

Answer 14

22 V

Question 15

Below what voltage will main batteries need a maintenance deep cycle recharge?

Answer 15

7 V

Question 16

What items are capable of being powered from the battery tie bus?

Answer 16

• Aux hydraulic pump
• APU Starter
• ESS DC Buses

Question 17

Below 20 V, approximately how long with it take to fully recharge the batteries?

Answer 17

90 Minutes

Question 18

What 3 items will illuminate the battery switch capsule lights?

Answer 18

• When the batteries are powering the ESS DC buses
• When the AUX HYD Pump is selected ON
• When starting the APU

Question 19

Which battery is utilized to close the main door when using the outside door switch?

Answer 19

Right battery, which is wired directly to the main door electrical control circuit

Question 20

What is the output rating of the HMG?

Answer 20

5 kVa = 100% on the synoptic indication

Question 21

How is the HMG powered?

Answer 21

Left hydraulic system pressure, or via the PTU (Right pressure, with fluid in the Left hydraulic system)

Question 22

HMG powers which buses?

Answer 22

L and R Standby AC Buses, AUX TRU (supplies power to the L and Right ESS DC buses) and the ESS AC Bus through the E Inverter

Question 23

What item will be lost with only one AC power source in flight?

Answer 23

Galley power

Question 24

How many TRUs are normally operating in flight?

Answer 24

5 = 2 Main, 2 ESS and 1 AUX

Question 25

Which TRU is not dedicated to a single bus?

Answer 25

AUX TRU

Question 26

If the right main TRU fails, what should automatically power the right main DC Bus?

Answer 26

AUX TRU

Question 27

If a generator fails, will a BPT or a NBPT occur?

Answer 27

BPT

Question 28

If a generator is selected off while running, will a BPT or a NBPT occur?

Answer 28

NBPT

Question 29

If a running engine is shutdown with the fuel control switch, will a BPT or a NBPT power transfer occur?

Answer 29

NBPT

Question 30

If an engine fails, will a BPT or a NBPT occur?

Answer 30

BPT

Question 31

If the ground service bus is selected ON, what will power the bus if DC external power is connected to the aircraft?

Answer 31

DC external power

Question 32

In flight, how is the ground service bus normally powered?

Answer 32

Right Main DC Bus

Question 33

When the ground service bus is turned on, what light turns on?

Answer 33

Lower beacon

Question 34

Which batteries are activated when the external battery switch is turned ON?

Answer 34

Both main batteries

Question 35

What buses are powered with an external DC power cart connected to the aircraft?

Answer 35

- L and R ESS DC - L and R Main DC - GND SVC Bus - ESS AC (via the E inverter)

Question 36

What electrical components are located under the forward floor?

Answer 36

TRUs and E Inverter

Question 37

What is the IDG load limit when operating at high ambient air temps?

Answer 37

45% (18 kVa) when greater than 43c in order to maintain steady state fuel temperatures below 95c

Question 38

Speedbrake limitation in HMG operations

Answer 38

Speedbrakes may be used, provided operation is slow (3 seconds for full range of handle movement)

Question 39

How is the left main TRU powered when the L MAIN TRU switch on the overhead panel is selected to "R AC"?

Answer 39

The L MAIN TRU receives power from the R MAIN AC bus

Question 40

What is the indication associated with a battery charger failure?

Answer 40

An amber BATT CHGR FAIL (L or R) CAS

Question 41

What will selecting the L BUS TIE switch to the ISLN position do?

Answer 41

Isolates the L MAIN AC bus from all power sources except the left IDG

Question 42

What is an IDG and how does it work?

Answer 42

Integrated Drive Generator - It operates like a constant speed transmission. As the engine speed changes, the CSD maintains the generator at a constant speed

Question 43

What is the function of the L and R MAIN TRU switches?

Answer 43

The on-side MAIN AC BUS powers each main TRU. In the unlikely event that the on-side MAIN AC BUS should fail, the L or R MAIN TRU switch can be selected to the opposite side MAIN AC bus to restore the TRU and its respective MAIN DC bus

Question 44

If using a L or R MAIN TRU switch, what will happen to the failed side ESS DC BUS?

Answer 44

Powered automatically by the AUX TRU

Question 45

How is the electrical power control panel normally configured?

Answer 45

5 in, 5 out

Question 46

In what situation can a TRU power more than one bus, and which buses can it power?

Answer 46

When the HMG and L ESS / R ESS switches are IN/ON, the AUX TRU can power both ESS DC buses

Question 47

If a ground service bus switch is selected ON with no external power connected to the aircraft, where will the GSB get its power?

Answer 47

Right battery

Question 48

Whenever the external battery is turned on, what light turns on?

Answer 48

Lower beacon

Question 49

What are two items that will cause one or both battery switch lights to illuminate even while one or more AC generators are operating?

Answer 49

Starting the APU or selecting the AUX HYD pump ON