Alternator vs Generator
Basic Theory
Advantages/Disadvantages
Inductance
• Moving magnetic field in relation to
conductor, generates electron flow
• Electricity is generated
• Faster movement, more flow
• Larger field, more flow
• Each conductor produces a fraction of
output
Generator
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Windings spin within magnetic field
RPM limited, low RPM, low output
Magnetic strength has low variability
Operates well at high engine RPM
Generates it’s own field and flow from
residual magnetism
• It turns, it works
Alternator
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Magnetic field spins within windings
High variability in gauss
Low RPM, strong magnet
High RPM, weaker magnet
Needs voltage to generate voltage
Dead battery, no output
Alternator/Generator
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Wide range of RPM
Lighter in weight
More delicate
Needs field current
More complicated
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Narrow RPM range
Heavier for output
Bulletproof
Needs to turn
Very simple system
Electrical System
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Battery
Alternator/Generator
Distributing busses/ Breakers
Switches
Devices/Appliances
Safeties
Battery
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Battery voltage, 24 volts
Stores energy for start/ ground ops
Stabilizes against surges
Charges back from alternator
System voltage, 28 volts
Why the difference?
Distributing Busses
• Direct power to devices
• Circuit protection
• In some cases, load shedding
Switches
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Energize circuit
Directly or remotely
Remote, contactors, relays or solenoids
Higher power items are remotely
controlled
• Switches themselves are high drain
• Knowledge is power
Devices/Appliances
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Radios, lights, fans etc.
High drain items
Resistance heat and lights
Transmitters
Passive receivers
In-Flight troubleshooting
Transponder, DME or Comm radio
Safeties
• Circuit breakers/Fuses
• Overloads
• Alt. control unit/Alt. field current
– Most are nuisance trips
– Reset and continue
– Do not reset 2nd time