Electrics

Question 1

Electric system.

Answer 1

28V DC system

Question 2

Power Generation (PG)
Describe the generators

Answer 2

Two 60A alternators
mounters bottom left of each engine
driven by a flat belt

Question 3

PG - What happens when the alternators are off?

Answer 3

Power is provided by the main battery

Question 4

PG - What is the L/R power output line connected to?

Answer 4

The LH/RH main bus via LH/RH alternator relay and a 70A circuit breaker

Question 5

PG - What are the main buses connected to?

Answer 5

The Battery Bus via a 90A circuit breaker

Question 6

PG - Purpose of generator output lines?

Answer 6

Generator output lines run through current sensor for each alternator
-> Which provides power supplied to electric system by an alternator. Including battery charging

Question 7

PG - What happens when the main battery fail?

Answer 7

The field of each alternator is energised by two 12V 1.3Ah sealed lead acid batteries (excitation batteries) connected in series - installed in baggage nose compartment

Question 8

PG - When are the Back up batteries used?

Answer 8

When the main battery and alternators fail. The two separate 24V 1.3Ah Back up batteries power each ECU

Question 9

PG - What do the LH/RH engine master connect?

Answer 9

They connect the excitation battery to alternator field via a 5A fuse

Question 10

PG - Why does each alternator have a control unit?

Answer 10

To measure alternator output voltage,
Controls current through alternator field coil via a pulse-width modulated signal.
-> so field signal modulated to keep output voltage stable in all load and speed situations

Question 11

Storage (S) - Main battery storage?

Answer 11

24V 10Ah lead acid battery

Question 12

S - What is the Main battery connected to?

Answer 12

The Hot battery bus and Battery bus via the battery relay - installed in relay junction box

Question 13

S - What controls the battery relay?

Answer 13

The Electric master

Question 14

S - What is the Non-rechargeable dry battery for?

Answer 14

A source for the artificial horizon and flood light

Question 15

S - When is the Non-rechargeable dry battery used?

Answer 15

When the emergency switch is on, the artificial horizon and flood light supplied with power for 1.5hrs.

Question 16

S - How many times can you use the Non-rechargeable dry battery be used?

Answer 16

Once. Has to be replaced after use or every 2years.

Question 17

Distribution (D) - What distributes power?

Answer 17

Hot Battery bus, Battery bus, LH/RH ECU Bus, LH/RH Main bus and Avionic Bus

Question 18

D - What does the Hot battery bus connect to?

Answer 18

To the Main battery

Question 19

D - Key things about the Battery bus.

Answer 19

Connected to main battery
Via Battery relay
Controlled by Electric master

Question 20

D - Key things about the ECU Bus.

Answer 20

Connected to LH/RH main bus via a diode

Connected to power output line of the alternator via a diode and 30A circuit breaker

Question 21

D - How long does ECU Backup battery provide power for?

Answer 21

30 mins if there’s a complete electrical failure.

Question 22

D - What does a Main bus connect to?

Answer 22

A battery bus via a 90A circuit breaker

Question 23

D - What to the LH and RH Main bus power?

Answer 23

LH Main bus - consumers

RH Main bus - Avionics bus via Avionic master relay

Question 24

Consumer connections

Answer 24

Consumers connected to appropriate bus via automatic circuit breakers.

Question 25

Voltage min and max

Answer 25

Min - 24.1V

Max - 32.0V

Question 26

Amperage max

Answer 26

Max - 60A