B777 Electrical

Boeing 777 Electrics

Boeing 777 Electrics

1 / 15

What is the correct electrical panel configuration for normal flight?

BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches ON.

BUS TIE switches in ISLN, BATTERY switch ON, GENERATOR CONTROL switches ON

BUS TIE switches in AUTO, BATTERY switch ON, GENERATOR CONTROL switches OFF.

BUS TIE switches in AUTO, BATTERY switch OFF, GENERATOR CONTROL switches ON.

2 / 15

The main battery provides standby power to the following:

The hot battery bus, the battery bus, the captain’s flight instrument bus and the standby inverter.

The hot battery bus, the captain’s flight instrument bus, and the standby inverter.

The hot battery bus, the battery bus and the captain’s flight instrument bus.

The hot battery bus, the battery bus, the captain’s flight instrument bus, the left and center flight control PSAs, and the standby inverter.

3 / 15

What is the source of standby electrical power if the RAT sheds electrical power because of low hydraulic pressure?

APU.

Main battery.

DC busses.

Back up generators.

4 / 15

If the RAT is unable to maintain RPM, the RAT generator electrical load is shed until RPM is satisfactory. Power for standby electrical loads is provided by the main battery during deployment of the RAT and when RAT generator loads are shed.

True.

False.

The RAT is deployed automatically if both AC transfer busses lose power in flight. The RAT can be manually deployed by pushing the RAM AIR TURBINE switch on the overhead panel.

5 / 15

What is the secondary source of power for 'fly-by-wire' if one or more PMGs are unpowered?

DC busses.

Left transfer bus.

Hot battery bus.

Main AC busses.

6 / 15

Backup power is provided by one variable speed, variable frequency generator mounted on each engine. A frequency converter converts the generator frequency to a constant 400 Hz. Only one backup generator can power the converter at a time.

False.

True.

7 / 15

What is the correct source order for powering left and right main busses in flight?

Respective backup generator - APU generator - opposite backup generator.

Respective IDG - APU generator - opposite IDG.

APU generator - respective IDG - opposite IDG.

Opposite IDG - APU generator - respective IDG.

8 / 15

What is the primary source of DC power during normal flight?

APU battery.

Transformer rectifier units.

DC generators.

Main battery.

9 / 15

Which one of the following is not true about the ram air turbine (RAT) generator?

The RAT cannot be manually deployed by pushing the RAM AIR TURBINE switch if any of the AC transfer busses powered.

The RAT can supply electrical and hydraulic power simultaneously.

The RAT generator provides standby power to the C1 and C2 TRUs.

The RAT is deployed automatically if both AC transfer busses lose power in flight.

10 / 15

Which one of the following is not true about the standby inverter?

The standby inverter converts DC power to AC power.

The standby inverter is powered from the battery bus.

The standby inverter is powered from the ram air turbine (RAT) generator.

The standby inverter powers the AC standby bus if the left transfer bus is not powered.

11 / 15

Which one of the following is not true about the backup electrical system?

Right and Left backup generators power the converter at the same time.

Backup power is provided by one variable speed, variable frequency generator mounted on each engine.

A frequency converter converts the generator frequency to a constant 400 Hz.

If both IDGs and the APU generator are inoperative, a backup generator powers essential airplane equipment to reduce electrical loading on the backup generator, some of the systems becomes inoperative such as TCAS, Centre tank override/jettison pumps (centre tank fuel is unusable).

12 / 15

How are the busses powered if the right engine is started with the APU powering the left bus system and external power powering the right bus system?

The right engine generator powers both main busses.

External power continues to supply the right main bus.

There is no automatic switching till the left engine is started.

The right engine genrator automatically powers the right main bus.

13 / 15

Which one of the following is not true about the flight control DC electrical system?

Each PSA also uses a dedicated battery to prevent power interruptions to the related flight control DC bus.

Primary power for the flight control DC electrical system comes from permanent magnet generators (PMGs) housed within each backup generator.

Variable frequency PMG AC power is the unique power source for the power supply assemblies (PSAs).

Variable frequency PMG AC power is used by individual power supply assemblies (PSAs) to provide DC power to the three flight control DC busses.

14 / 15

Which one of the following is not true about integrated drive generators (IDGs)?

The IDG can be reconnected by the flight crew by pushing the respective DRIVE DISCONNECT switch.

The IDG drive can be disconnected from the engine by pushing the respective DRIVE DISCONNECT switch.

The IDG can be electrically disconnected from the busses by pushing the GENERATOR CONTROL switch to OFF.

The DRIVE light illuminates and the EICAS message ELEC GEN DRIVE L or R displays when low oil pressure is detected in an IDG.

15 / 15

Which one of the following is not true about the DC electrical system?

The DC electrical system includes the main DC electrical system and the flight control DC electrical system.

The C1 TRU powers the first officer's flight instrument bus.

The main DC electrical system uses four transformer-rectifier units (TRUs) to produce DC power.

The left TRU powers the left main DC bus.

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