Electrical

Question 0

How is the IDG driven?

Answer 0

By N2 powered drive transmission

Question 1

Stats on 3 IDGs:

Answer 1

Each generator supplies 3 phase, 115 volt, 400 cycle Alternating Current (AC) power.

Question 2

IDGs are cooled how?

Answer 2

Fan air & engine fuel flow

Question 3

How can an IDG auto disconnect?

Answer 3

High oil temp

Question 4

How do you manually disconnect an IDG?

Answer 4

Guarded switch on ovhd panel

Question 5

Can you reconnect a disconnected IDG?

Answer 5

No, only on gnd by mx

Question 6

What provides speed to APU IDG?

Answer 6

APU fuel control unit

Question 7

Is there a direct control switch for DC power?

Answer 7

No

Question 8

When normal DC pwr isn’t available, what supplies DC pwr?

Answer 8

Battery

Question 9

What bus is connected to the battery when the battery switch is off?

Answer 9

Hot batt bus ( also connected to APU starter)

Question 10

What busses are powered when the batt switch is on:

Answer 10

Hot batt bus, batt bus, sw’d hot batt bus

Question 11

With batt switch on, when stby pwr switch is in auto, what else receives pwr?

Answer 11

DC stby bus and AC stby bus VIA the static inverter

Question 12

What is the point of the GROUND SERVICE button?

Answer 12

Powering just gnd service buses instead of every bus when external pwr is connected/avail

Question 13

Where is the gnd service button?

Answer 13

Fwd flt attendant panel

Question 14

What busses does AC Trans bus 1 pwr?

Answer 14

AC gnd service bus 1, AC main bus 1, Galley bus C + D and AC stby bus

Question 15

What busses does AC Trans bus 2 pwr?

Answer 15

AC gnd service bus 2, AC main bus 2 , galley bus A+B

Question 16

What does the GND PWR AVAIL light mean?

Answer 16

This light indicates not only that the power is connected, but that the power is of good quality.

Question 17

How many APU GEN switches need to be in the on position to power both transfer buses?

Answer 17

Just 1, the BTBs will close and both transfer buses will be powered. However, a source off light on the opposite side will illuminate

Question 18

Do engine generators automatically come online?

Answer 18

No, they must be selected on by the respective switches

Question 19

What does a SOURCE OFF light mean?

Answer 19

The SOURCE OFF light illuminates when the respective Transfer Bus is powered through the Bus Tie System.

Question 20

Does the APU generator automatically come online?

Answer 20

No. It must be selected on

Question 21

If the AC system is powered by one eng gen, what loads get shed in what order?

Answer 21

1. Galley pwr on Trans bus 2
2. Galley pwr on Trans bus 1
3. Main bus 1&2

Question 22

Inflight, if the aircraft is pwred by just the APU, what is shed?

Answer 22

1. All galley buses shed

2. Main bus 1&2

Question 23

On the ground, if only powered by APU, which buses are pwred?

Answer 23

APU tries to pwr all buses

Question 24

Battery bus primary & alternate sources of pwr:

Answer 24

Normal: TR 3 Alternate: battery charger or battery

Question 25

The cross bus tie is normally:

Answer 25

Closed

Question 26

When does the cross bus tie normally open and why?

Answer 26

The normally closed Cross Bus Tie relay opens when the autoflight Approach mode captures the glideslope with the Flight Director or Autopilot in use. This feature provides electrical isolation during an approach, so that a fault on one system will not affect another system.

Question 27

What does the STANDBY POWER OFF light mean?

Answer 27

The STANDBY PWR OFF light illuminates when the Standby AC Bus, the Standby DC Bus, or the Battery Bus is not powered.

Question 28

How does the bus transfer switch work?

Answer 28

The BUS TRANSFER Switch in the AUTO position allows the BTB's to operate automatically to maintain power on the Transfer Buses from any available source of AC power. In AUTO, the DC Cross Tie Relay is closed unless the glideslope is captured by the autopilot and/or the flight director.

Question 29

What happens when the bus transfer switch is in the off position?

Answer 29

The BUS TRANSFER Switch in the OFF position isolates Transfer Bus 1 from Transfer Bus 2 if one IDG is supplying power to both Transfer Buses. In addition, the OFF position opens the DC Crosstie Relay.

Question 30

What does the TRANSFER BUS OFF light mean?

Answer 30

The TRANSFER BUS OFF light illuminates when the respective Transfer Bus is not powered.

Question 31

What does the GEN OFF BUS light mean?

Answer 31

The GEN OFF BUS light illuminates when the respective IDG is not powering the related Transfer Bus. The engine Generator Switches apply power directly to the related Transfer Bus.

Question 32

Inflight or on the ground with loss of all AC power, the AUTO position of the STANDBY PWR SWITCH allows the:

Answer 32

AC Standby Bus to be powered by the Inverter - which is powered by the battery: and the DC Standby Bus is also powered by the battery.

Question 33

The OFF position of the Standby Power switch:

Answer 33

removes all power from the AC Standby Bus and the DC Standby Bus.

Question 34

The digital display to see electrical components outputs and status needs what to operate?

Answer 34

Batt bus pwr

Question 35

What does the BAT DISCHARGE light mean?

Answer 35

A BAT DISCHARGE light illuminates when excessive battery discharge is detected with the BAT switch ON. This light can illuminate during an APU start.

Question 36

What does TR UNIT light mean?

Answer 36

A TR UNIT light illuminates when any TR fails on the ground, or inflight it monitors TR1 as well as a combined failure of both TR2 and TR3.

Question 37

What does the ELEC light mean?

Answer 37

An ELEC light illuminates on the ground when a fault exists in the DC power system or Standby power system. This light is inhibited inflight.

Question 38

What does the DRIVE Light mean?

Answer 38

A DRIVE light indicates problems with the generator drive unit.

Question 39

When will the DRIVE light illuminate?

Answer 39

It illuminates upon IDG failure, engine shutdown, IDG automatic disconnect, or manual IDG disconnect.

Question 40

Describe the automatic online IDG feature:

Answer 40

The automatic IDG on-line feature allows the engine generators to automatically come on-line if takeoff is made with the APU powering the electrical systems. This is a one time operation for each flight and protects the aircraft from an inadvertent loss of electrical power. The automatic engine generator on-line feature only operates once inflight if the on-line APU power fails or is turned OFF.