Electrical

Question 1

What are the power sources for the AC Buses during normal operating conditions for AC Buses 1 & 2?

Answer 1

▪ Respective Engine Generator (IDG 1 or 2).
▪ External power
▪ APU generator

Question 2

What are the power sources for the AC Buses during normal operating conditions for the AC ESS Bus?

Answer 2

▪ Normally by AC Bus 1
▪ AC Bus 2 manually, when AC ESS FEED pb is selected to ALTN
▪ AC Bus 2 automatically, via the auto switching logic

Question 3

Describe the electrical system’s power priority?

Answer 3

1st Respective engine generator
2nd External power (If selected ON)
3rd APU generator
4th Opposite engine generator

Question 4

Recall the functions of the BUS TIE pb when selected to OFF?

Answer 4

OFF – Power priority order logic is deactivated.

• AC Bus 1 and 2 can only be powered by their respective engine generator.
• External or APU generator power cannot be applied to the aircraft.

Question 5

What is the purpose of the AC ESS FEED pb?

Answer 5

The AC ESS FEED pb is used to manually command AC Bus 2 to power the AC ESS Bus.
When in the “light out” configuration:
▪ AC Bus 1 powers AC ESS Bus. This the normal configuration.
▪ Should AC Bus 1 fail, AC Bus 2 automatically powers AC ESS BUS.

Question 6

What happens when the AC ESS FEED pb when selected to ALTN?

Answer 6

▪ AC Bus 2 is commanded to power AC ESS Bus regardless of the status of AC Bus 1.
▪ ALTN appears only when the pb is selected.

Question 7

What information is provided by the electrical power legends on the ECAM ELEC page for GEN 1 & GEN 2 and APU GEN?

Answer 7

▪ Percentage of output
▪ Voltage
▪ Frequency

Question 8

What information is provided by the electrical power legends on the ECAM ELEC page for EXT PWR?

Answer 8

▪ Voltage

▪ Frequency

Question 9

o In-flight – When on single generator power, what does GALLEY SHED indicate?

Answer 9

That the galley’s main bus has been automatically depowered. However, its secondary bus remains powered.

Question 10

o When the GALLEY pb is selected OFF, GALLEY SHED indicates what?

Answer 10

The galley’s main and secondary buses are depowered.

Question 11

To avoid damage to the IDG disconnect mechanism DO NOT:

Answer 11

▪ Disconnect unless the engine is operating or is wind-milling.
▪ Hold the pb(s) for more than three (3) seconds.

Question 12

Explain the color coding convention of the circuit breakers for a Green circuit breaker?

Answer 12

▪ Circuit breaker is monitored by the Flight Warning Computers (FWCs).
▪ C/B TRIPPED message appears ECAM when CB is open for more than 1 minute.

Question 13

Explain the color coding convention of the circuit breakers for a Black circuit breaker?

Answer 13

▪ Circuit breaker is not monitored by the FWCs therefore, no “C/B TRIPPED” message is generated.
▪ The system which the circuit breaker supports may be monitored by the FWCs

Question 14

Explain the color coding convention of the circuit breakers for a Yellow circuit breaker?

Answer 14

▪ Pulled when flying on batteries only.

Question 15

Explain the color coding convention of the circuit breakers for a Red circuit breaker?

Answer 15

▪ The red cap around the circuit breaker prevents it from being reset.
▪ Provide circuit protection to the Wing Tip Brakes (WTB).

Question 16

How is Generator 1 is affected when the GEN 1 LINE pb is selected OFF?

Answer 16

❇️Opens generator 1’s line contactor, in affect isolating it from the remainder of the aircraft’s electrical system.
❇️Generator 1 is limited to only powering one fuel pump in each wing tank.

Question 17

Describe the two methods of activating the emergency generator?

Answer 17

1. Automatically:
   ▪ Loss of power to AC Bus 1 and 2 in flight will automatically deploy the Ram Air Turbine (RAT) and activate the emergency generator. o
2. Manually:
   ▪ Selecting the red guarded MAN ON pb on the EMER ELEC PWR panel will manually deploy the Ram Air Turbine (RAT) and activate the emergency generator.

Question 18

Explain the configuration called “Emergency Generation After Loss of All Main Generators”.

Answer 18

It means that AC Buses 1 and 2 are unpowered and the Emergency generator is powering:

• AC ESS Bus
• DC ESS Bus, through the ESS TR
• AC and DC ESS SHED buses through their ESS Buses

Question 19

What occurs to the emergency generator when the landing gear is lowered?

Answer 19

The emergency generator is automatically deactivated, and the aircraft batteries become the sole source of electrical power.

Question 20

Recall the location and use of the MAINT BUS switch.

Answer 20

▪ Located on the electrical panel on the ceiling of the forward galley.
▪ When selected ON, allows external power for ground servicing without energizing the entire aircraft’s electrical system.
▪ Only requires external power to be connected and have good Volts and Freqs.

Question 21

Recall what would be powering the aircraft in this scenario: - both engines are shut down - the APU START pb indicates AVAIL - the EXT PWR pb indicates ON?

Answer 21

The aircraft is being powered by External Power because it has priority over the APU generator.
▪ The AVAIL light indicates that the APU is “On Speed”
▪ The ON light in the EXT PWR pb indicates that external power has been selected