Electric

Question 1

The DC electrical system is supplied by:

Answer 1

3 NiCad batteries (24v DC)
2 Engine driven DC Starter-Generators (28.5v DC)
2 Transformer Rectifier Units (28v DC)
1 Auxiliary Power Unit (28v DC)

Question 2

Name the 7 DC busses.

Answer 2

Battery
Left and Right Essential
Left and Right Main
Left and Right Secondary

Question 3

The AC electrical system is supplied by:

Answer 3

2 engine driven AC generators that provide 115 volt, three-phase, variable AC power

Question 4

Automatic reconfiguring of the electrical system is controlled by the…

Answer 4

Electrical Power Control Unit (EPCU).

Question 5

Where are the batteries located?

Answer 5

Main and Aux - Lower Left section of nose compartment

Standby - Upper Left section of nose compartment

Question 6

Volts and amp hours of batteries

Answer 6

Main and Aux - 24v, 40 amp hour

Standby - 24v 17 amp hours

Question 7

Batteries that assist engine start

Answer 7

Main and Aux

Question 8

How long will batteries supply emergency power?

Answer 8

Approximately 45 minutes

Question 9

Which battery is connected to the “hot” battery bus

Answer 9

Standby battery

Question 10

BATTERY MASTER switch

Answer 10

Closes 3 contactors directly connecting all three batteries to the Essential DC buses

Question 11

How is the EPCU powered?

Answer 11

Indirectly from essential busses, Primarily from standby battery

Question 12

MAIN/AUX/STBY BATT switch

Answer 12

Directly connects respective battery to its main bus

Question 13

What busses is the main battery connected to?

Answer 13

Right main DC bus (2 way flow), Right Essential Bus

Question 14

What busses is the aux battery connected to?

Answer 14

Left Main DC bus (2 way flow), Left Essential Bus

Question 15

What busses is the standby battery connected to?

Answer 15

Left Main DC bus (1 way flow for charging), Right Essential Bus

Question 16

Battery temperature range

Answer 16

Amber - 50C to 65C

Red - greater than 65C

Question 17

What bus is external DC power is received by?

Answer 17

Left Main DC Bus

Question 18

When will the EPCU automatically disconnect from the external power source?

Answer 18

External DC voltage exceeds 31 volts or drops below 22 volts

Question 19

What are the DC starter-generators driven by?

Answer 19

Engine Accessory Gearbox

Question 20

How are the DC starter-generators cooled?

Answer 20

Air cooled

Question 21

How are the DC starter-generators monitored and controlled?

Answer 21

Respective Generator Control Unit (GCU)

Question 22

At what point does the GCU convert the DC starter-generator from starter mode to generator mode?

Answer 22

Nh of 50% during start

Question 23

What are the volts and amps of the DC starter-generators.

Answer 23

28.5 volts, 400 amps

Question 24

How are the TRUs cooled?

Answer 24

Air cooled

Question 25

What do the TRUs do?

Answer 25

Convert 115 volt 300 amp variable frequency AC power into 28 volt DC power

Question 26

How can you manually control the TRUs?

Answer 26

Respective circuit breaker located on the 115 volt variable AC circuit breaker panel

Question 27

What is the APU start-generator rated at?

Answer 27

28 volts, 400 amps

Question 28

When does automatic load shedding occur?

Answer 28

Loss of more than two DC power sources

Question 29

What is EPCU emergency mode?

Answer 29

Loss of both DC generators and one TRU

Question 30

What happens during EPCU emergency mode?

Answer 30

EPCU automatically disconnects the batteries from the main busses leaving them only able to supply power to essential busses (approximately 45 minutes)

Question 31

Can the engines be restarted in the air in EPCU emergency mode?

Answer 31

Yes, EPCU will allow batteries to be momentarily reconnected to main busses

Question 32

What happens when the EPCU detects a bus fault?

Answer 32

Automatically takes offline all the DC components associated with the faulty bus via isolation

Question 33

How are the AC generators cooled?

Answer 33

Oil cooled

Question 34

How are the AC generators driven?

Answer 34

Propeller Reduction Gearbox

Question 35

How are the AC generators rated?

Answer 35

115 volt, three phase, variable frequency AC power

Question 36

What components are powered by AC power?

Answer 36

- deicing/anti-icing heaters - standby hydraulic pump (#1 system) - TRUs - #1 and #2 aux fuel pumps - galley loads

Question 37

Where are circuit breaker panels located?

Answer 37

- four flight compartment panels - DC contactor box in nose compartment - AC contactor box in left and right wheel well - two wardrobe circuit panels - galleys

Question 38

#1 or #2 DC GEN HOT caution light

Answer 38

DC generator temperature is more than 166C

Question 39

#1 or #2 AC GEN HOT caution light

Answer 39

AC generator temperature is more than 166C

Question 40

#1 or #2 DC GEN caution light

Answer 40

DC generator not connected to its bus due to a source fault condition, the DC toggle switch is set to OFF, or the external DC power is energizing the main feeder busses

Question 41

#1 or #2 AC GEN caution light

Answer 41

AC generator not connected to its bus due to a source fault condition, the AC toggle switch is set to OFF, or the external AC power is energizing the main feeder busses

Question 42

STBY/MAIN/AUX BATTERY caution light

Answer 42

battery is not connected to its main feeder bus for charging

Question 43

L or R TRU HOT caution light

Answer 43

TRU temperature is more than 71C

Question 44

L or R TRU caution light

Answer 44

AC secondary feeder bus not energized by its related TRU because of a source fault condition or the AC generator toggle switches are set to OFF

Question 45

DC BUS caution light

Answer 45

EPCU has reconfigured the main 28 VDC generation system because of a source or fault condition

Question 46

L or R AC BUS caution light

Answer 46

AC generator not connected to its bus due to a right bus fault condition or the AC generator contractor is open while the generator is operating and the AC generator toggle switch is set to ON

Question 47

STBY/AUX/MAIN BAT HOT warning light

Answer 47

battery temperature is greater than 71C