Download Aircraft Electrical Systems

Lesson 10: Aircraft
Electrical Systems
Aircraft Electrical Systems
• A circuit must have at least three parts.
Aircraft Electrical Systems
• A circuit must have at least three parts.
• The source
Aircraft Electrical Systems
• A circuit must have at least three parts.
• The source
• The electron transportation and distribution
system
Aircraft Electrical Systems
• A circuit must have at least three parts.
• The source
• The electron transportation and distribution
system
• The load (Where the work is done)
Series And Parallel Circuits
• Series Circuit
• All electrons must flow through all active
components.
• The amount of voltage dropped across the
filament is always less than the total.
• Voltage drop depends on the amount of
resistance of the individual load.
Series And Parallel Circuits
• Parallel Circuit
• A portion of the electrons flow through each
filament.
• The amount of voltage drop is equal to the total
voltage produced by the source.
Voltage And Current Measuring
Instruments
• Current and voltage are the most commonly
measured variables.
• Voltmeters
• Ammeters
Voltage And Current Measuring
Instruments
• Voltmeters (Parallel)
• Measures current but indicates values of
voltage.
• Indicates electrical system condition.
Voltage And Current Measuring
Instruments
• Ammeters
• Measures current flow
• Battery is charging when electrons are flowing
from the positive terminal.
• This would be a positive indication.
The Aircraft Electrical
System
The Aircraft Electrical System
• Source
• 12 volt battery with the negative terminal
connected to the airframe (negative ground).
• Master solenoid
• Master switch
The Aircraft Electrical System
• The Starter Circuit
• Starter switch circuit (control circuit)
• Starter solenoid circuit (motor circuit)
• The master switch/solenoid circuit must also
be connected.
The Aircraft Electrical System
• The Busbar
• Rigid point that is a convenient place to
terminate many wires neatly and safely.
• Connected to the positive terminal of the
battery, when the master switch is on.
• Same electrical potential as the battery.
• Circuit breakers are often mounted.
The Aircraft Electrical System
• The Alternator
• The alternator switch completes a circuit to the
voltage regulator.
• The voltage regulator samples the system
voltage and increases or decreases the field
voltage which limits alternator output.
The Aircraft Electrical System
• Ammeters And Loadmeter In The Circuit
• Installed between the master solenoid and the
busbar.
• Senses the amount and direction of current
flow in the battery circuit.
• Installed between A terminal of the alternator
and the busbar.
• Senses current flow (in one direction), or
output, of the alternator (loadmeter).
Ignition Systems
Battery Ignition System
Magnetos
• Completely independent of the electrical system of
the airplane.
• Primary current is interrupted by a set of breaker
points, and high voltage for the spark plugs comes
from the voltage step-up in the magneto coil.
• Rotating Magnet Magneto
Rotating Magnet Magneto
Rotating Magnet Magneto
• Resultant Flux (E-gap)
• Maximum current is flowing several degrees
after neutral.
Rotating Magnet Magneto
Rotating Magnet Magneto
• Dual Magnetos
• High-tension Magnetos
• Low-tension Magnetos
High-tension Magneto
Low-tension Magneto
Rotating Magnet Magneto
• Aids To Starting
• Magnetos provide a good, hot spark at idle, at
cruise, and at high speed.
• But not when the engine is turning slowly
during start.
» Impulse Coupling
Impulse coupling
• A small spring-loaded coupling between the
magneto shaft and the engine drive gear.
Impulse coupling
Vibrator starting system
“Shower of Sparks”
• Pulsating DC from the induction vibrator is directed
into the magneto coil.