Wiring And Distribution

Question 1

Wiring Methods

Answer 1

Uni - Pole - AC structure as returned (Earth attached to ac structure)
- Higher risk of short circuit

Di-Pole - Complete cable running back to circuit)
- Used in non conduction airframes
- Less risk of short circuit
- More wiring
- Harder to fault find

Question 2

Short Circuit

Answer 2

Occurs when part of a wire carrying current touches another wire or part of circuit and gives electricity a path of less resistance

Question 3

Open Circuits

Answer 3

Occurs when circuit is broken - no current flows
Switches set to open are open circuits

Question 4

Busbars

Answer 4

Distribute power to the loads or consumers (Distribution point)

Low resistance/impedance conductor
Copper of aluminium
Connected to each load in parallel
Cannot connects two generators to 1 bus

Hot - Connected to battery directly cannot be disconnected

Battery - Connected to battery can be switched off by battery switch

Main Bus - Generators connected to main busbars (APU/Engines) (Ground Busbar)

Essential Bus Bar - services for safety of flight (instruments/avionics)

Emergency Bus -

Question 5

Tie Bus

Answer 5

Paralleled Systems:
- Connects the generator busbars

Split bus system:
- Connects the generator busbars after failure of one generator

No loss of AC or DC
Need to load shed

Question 6

DC Power from AC

Answer 6

3 Transformer rectifier units covert 115v 400hZ AC into 28v DC

Question 7

Hot Bus

Answer 7

Connected directly to the battery hard wired cannot be disconnected

Useful for emergency lighting etc

Question 8

Battery Bus

Answer 8

Connected to the battery

Can be switched off using battery switch

Question 9

Main Bus

Answer 9

Generators are connected to the main bus bars

Question 10

Essential bus

Answer 10

Services for the essential safety of the flight
This are AC and DC

Flight controls/avionics etc