Lesson 10: Aircraft Electrical Systems

1. Lesson 10: Aircraft Electrical Systems

2. Aircraft Electrical Systems • A circuit must have at least three parts.

3. Aircraft Electrical Systems • A circuit must have at least three parts. • The source

4. Aircraft Electrical Systems • A circuit must have at least three parts. • The source • The electron transportation and distribution system

5. 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)

6. 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.

7. 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.

8. Voltage And Current Measuring Instruments • Current and voltage are the most commonly measured variables. • Voltmeters • Ammeters

9. Voltage And Current Measuring Instruments • Voltmeters (Parallel) • Measures current but indicates values of voltage. • Indicates electrical system condition.

10. 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.

11. The Aircraft Electrical System

12. The Aircraft Electrical System • Source • 12 volt battery with the negative terminal connected to the airframe (negative ground). • Master solenoid • Master switch

13. 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.

14. 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.

15. 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.

16. 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).

17. Ignition Systems

18. Battery Ignition System

19. 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

20. Rotating Magnet Magneto

21. Rotating Magnet Magneto • Resultant Flux (E-gap) • Maximum current is flowing several degrees after neutral.

22. Rotating Magnet Magneto

23. Rotating Magnet Magneto • Dual Magnetos • High-tension Magnetos • Low-tension Magnetos

24. High-tension Magneto

25. Low-tension Magneto

26. 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

27. Impulse coupling • A small spring-loaded coupling between the magneto shaft and the engine drive gear.

28. Impulse coupling

29. Vibrator starting system“Shower of Sparks” • Pulsating DC from the induction vibrator is directed into the magneto coil.