B-777 Electrical

Front 1

How many generators are there?

Back 1

10

2 X IDG's

4 X PMG's

APU

RAT

2 X Backup Gens

Front 2

Conditions for RAT deployment in flight?

Back 2

1. If BOTH AC transfer buses lose power in flight. OR

2. Both engines have failed AND center system hydraulic pressure is low OR

3. All 3 hydraulic system pressures are low

Front 3

ELMS

Back 3

Electrical Load Management System

Front 4

What will cause an IDG to disconnect automatically in flight?

Back 4

High drive oil temperature (HOT)

Front 5

Can an IDG be reconnected in flight by crew?

Back 5

No

Front 6

Can a single source of AC power the entire system?

Back 6

Yes

Front 7

In flight what will cause APU to automatically start?

Back 7

When both transfer busses are unpowered

Front 8

When do the external power AVAIL lights illuminate?

Back 8

Primary power source voltage and frequency are within limits

Front 9

To use external power what needs to be on in addition to external power being AVAIL?

Back 9

Battery switch

Front 10

Power priority for powering the left AND right main busses on the ground

Back 10

On side IDG

APU

Cross side IDG

Front 11

How many PMG's does each back-up generator have?

Back 11

2

Front 12

How many batteries are installed and what are they called?

Back 12

APU and Main plus a separate battery for the emergency lights

Front 13

What powers the APU electric starter when sufficient bleed air exisits?

Back 13

APU Battery

Front 14

What secondary power source will power the centre PSA if the PMG's fail?

Back 14

Captain flight instrument bus

Front 15

Can the RAT be reconnected in flight by the crew?

Back 15

No

Front 16

What power source does the RAT use to deploy automatically in flight?

Back 16

Hot battery bus OR APU battery bus

Front 17

How do you know ELMS is load shedding?

Back 17

LOAD SHED appears on electrical synoptic page

Front 18

In what order does the ELMS load shed?

Back 18

Galley

Utility busses

Individual AC components

Front 19

How long can the Main battery provide standby power?

Back 19

10 minutes

Front 20

How is and when is the GROUND HANDLING BUS powered?

Back 20

Powered by APU generator or primary external power.

It is only powered on the ground

Front 21

If 1 or more of the PMG's fail in flight how is backup power provided to the flight control DC buses?

Back 21

The main DC buses or captain's flight Instrument bus will power the FC DC buses

Front 22

How does the system avoid an interruption of power to the PSA if a transfer is required?

Back 22

Batteries for each FC bus that lasts upto 1 minute

Front 23

During an autoland (LAND 3) how are autopilots being powered?

Back 23

1 individual source per autopilot

Front 24

On the ground with no engines running or start cart connected what switch on the electrical panel needs to be on to start the APU?

Back 24

Battery switch. The main battery powers the APU inlet door.

Front 25

What buses does the primary and secondary external provide power to?

Back 25

Both main buses provided the battery switch is on

Front 26

Is anything available to convert DC to AC power in case of just battery power being available?

Back 26

Yes a standby inverter that operates if the left transfer bus is not powered

Front 27

If RAT deploys in flight what does it provide power to and in turn how does that help crew?

Back 27

C1/C2 TRU. Which means crew have power to captain and FO flight instruments

Front 28

If emergency power is provided by the main battery will the FO flight instruments work?

Back 28

No, just captain

Front 29

What is the back-up power source and how does it receive it's power?

Back 29

2 back-up generators, connected to the N2 accessory drive. Therefore an engine needs to be powered to provide power.

Front 30

When do the backup generators provide power to the system and what bus do they power?

Back 30

When only 1 main AC generator is available

Power to 1 or both main AC buses is lost

APP mode selected for Autoland

Automatic test after engine start

Power provided to the transfer buses

Front 31

What bus powers the ground service bus and what is that used for?

Back 31

Right main bus

It powers the;

Main battery charger

APU Battery charger

Cabin lighting

Front 32

When do the DRIVE lights illuminate amber?

Back 32

When IDG oil pressure is low

Front 33

On the ground if the battery switch is in the ON position and AC power has subsequently been lost what will happen?

Back 33

Standby buses and emergency lighting will come on

AND

Left inboard, outboard, upper DU and left CDU are powered

Front 34

When will the backup generator OFF light illuminate in amber? (4)

Back 34

Switch position

OR

Internal fault

OR

Engine shutdown

OR

Fire switch OUT

Front 35

When will the battery switch OFF light illuminate?

Back 35

When aircraft has AC power and the battery switch is OFF

Front 36

Below 1500' with LAND 3 what does the Electrical system do?

Back 36

Isolate to provide 3 sources of power.

Left IDG - Captain inst., Left transfer and left main DC

B/U gen - FO inst., right transfer and right main DC

Right IDG - Standby AC and Battery bus