B777 Electrical

Boeing 777 Electrics

Boeing 777 Electrics

1 / 15

Which condition(s) cause the ELEC GEN DRIVE L EICAS message to display?

Either A or B is correct

Generator drive oil temperature is high.

GENERATOR CONTROL switch selected to OFF.

Generator drive oil pressure is low.

2 / 15

The main battery provides standby power to the following:

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

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

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

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?

Main battery.

Back up generators.

DC busses.

APU.

4 / 15

Which one of the following is not true about the APU generator?

In flight, when both transfer busses are unpowered, the APU starts automatically, regardless of APU selector position.

The APU generator is electrically identical to the IDG generators.

The APU generator cannot power both main busses at the same time.

If no other power source is available when the APU generator becomes available, the APU generator automatically connects to both main AC busses.

5 / 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.

True.

False.

6 / 15

Which of the following is not a main AC electrical power source?

Transformer Rectifier Units (TRUs).

APU generator.

Left and right engine integrated drive generators (IDGs).

Primary and secondary external power.

7 / 15

Bus tie relays, controlled by BUS TIE switches, isolate or parallel the right and left main busses. When both BUS TIE switches are set to AUTO, the bus tie system operates automatically to maintain power to both main busses.

False.

True.

8 / 15

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

APU battery.

DC generators.

Main battery.

Transformer rectifier units.

9 / 15

Which one of the following is not true about the Primary External Power?

If a single IDG powers both busses, pushing the PRIMARY EXTERNAL POWER switch ON connects primary external power to both busses and removes the IDG source.

If both busses are powered from secondary external power, pushing the PRIMARY EXTERNAL POWER switch ON connects primary external power to the both main busses.

If the APU generator is running, pushing the PRIMARY EXTERNAL POWER switch ON connects primary external power to the right main bus, leaving the previous source connected to the left main bus.

When the Primary power source voltage and frequency are within limits, the primary external power AVAIL (available) light illuminates.

10 / 15

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

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

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

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.

11 / 15

Which bus operates only on the ground?

The left main AC bus.

The ground handling bus.

The right transfer bus.

The ground service bus.

12 / 15

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

The standby inverter is powered from the battery bus.

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

The standby inverter converts DC power to AC power.

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

13 / 15

How can you power the ground handling bus before shutdown if no external power is available?

Select the ground handling bus ON.

Deploy the RAT.

Start the APU.

The bus is powered as long as the right main bus is powered.

14 / 15

Will the IDG disconnect automatically for high temperature?

yes

no

15 / 15

Does electric power has priority over hydraulic power from the RAT?

yes

no

Hydraulic has priority, and if electric is shed, only the CA instrument bus is powered through the main battery

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