AC electrical

Question 0

What is the main source of electrical power - AC or DC?

Answer 0

AC

Question 1

Whats the difference between 757 & 757 ER ELECTRICAL SYSTEM?

Answer 1

ER has HDG (hydraulic driven generator)

Question 2

What is the electrical system comprised of ?

Answer 2

1) AC MAIN
2) DC MAIN
3) Battery Stby
4) HDG (ER)

Question 3

What are the main AC POWER SOURCES?

Answer 3

Left & right IDG’s

APU Generator

Question 4

What are the 2 main features of the IDG’s?

Answer 4

1) Automatic control

2) system protection

Question 5

What is the priority sequence for AC power?

Answer 5

1) external power
2) onside generator
3) APU
4) opposite side generator

Question 6

Is there an indication for galley buses?

Answer 6

No

Question 7

What does the ground service bus power?

Answer 7

1) MAIN BATTERY CHARGER
2) APU BATTERY CHARGER
3) MISCELLANEOUS CABIN & SYSTEM LOADS

Question 8

What is the purpose of the ground handling bus?

Answer 8

Provided for loads such as cargo handling and equipment energized ONLY during ground ops

Question 9

How is the ground handling bus powered?

Answer 9

ONLY by APU or EXTERNAL power - ONLY on the GROUND

Question 10

How are the 3 autopilots powered during autoland?

Answer 10

LEFT MAIN

1) L AUTOPILOT
2) CA FLT INTSTRUMENT TRANSFER BUS

RIGHT MAIN

1) R AUTOPILOT
2) FO FLT INSTRUMENT TRANSFER BUS

BATTERY / STANDBY
1) C AUTOPILOT

Question 11

DURING AUTOLAND

What happens if loss of GEN above 200’

Answer 11

BUS TIES CLOSE - operating GEN POWERS BOTH AC BUSSES

LEFT MAIN POWERS CENTER AUTOPILOT

NO LAND 3 - appears on autoland status annunciator

Question 12

DURING AUTOLAND

What happens with loss of GEN BELOW 200’?

Answer 12

BUS TIES REMAIN OPEN

AUTOPILOT ON FAILED GEN SIDE IS UNPOWERED

FLIGHT INSTRUMENTS REMAIN POWERED

AUTOLAND CONTINUES USING 2 AUTOPILOTS

Question 13

What is the purpose of the FLIGHT INSTRUMENT TRANSFER BUSSES?

Answer 13

TRANSFER POWER TO OPPOSITE MAIN BUS IN CASE OF ASSOCIATED MAIN BUS FAIL

Question 14

WHAT IS THE PURPOSE OF THE HYDRAULIC DRIVEN GENERATOR ON THE 757 ER ?

Answer 14

IF BOTH MAIN AC BUSES ARE LOST - CA INSTRUMENTS ARE POWERED BY HDG TO COMPLY WITH ETOPS REQUIREMENTS

Question 15

WHAT IS THE PRIORITY OF ELECTRICAL LOAD SHEDDING?

Answer 15

SHEDS LEAST IMPORTANT ITEMS FIRST

1) GALLEY
2) UTILITY BUSSES
3) INDIVIDUAL EQUIPMENT ITEMS ON MAIN AC

Question 16

How can you shed UTILITY BUSSES ON THE GROUND WITHOUT ENGINES RUNNING?

How do you reset them?

Answer 16

Advance thrust levers

Push utility BUS BUTTONS OFF THEN ON

Question 17

What are some important items on the L AC bus?

Answer 17

Some Pitot heat
L& C flight directors
Flap indicator
L& C Autopilot 
Electronic Engine Control

Question 18

what does the ISLN light mean?

Answer 18

L or R BUS ISOLATED

Question 19

What does the DRIVE light on the GEN DRIVE DISC switch mean?

Answer 19

Generator drive oil

temp high

Or

Pressure is low

Question 20

If you push the GEN DRIVE DISC switch - is it reversible?

Answer 20

No

Question 21

If you get a MAIN BAT DISCH message - how long do you have before loosing standby bus?

Answer 21

Aprox 30 mins

Question 22

What does an OFF light on the STBY POWER panel mean?

Answer 22

One or more of the

AC standby
DC standby
Battery bus

Not powered

Question 23

What are the 3 main functions of the bus tie system?

Answer 23

Prevents paralleling

Maintains bus power

Isolates faults

Question 24

How can you get the ground service bus online if it is off on the ground ?

Answer 24

Ground service button on the forward flight attendant panel