Unit 1-7 Flashcards
Energy cannot be _____ or _____, only _____ from one form to _____.*
created
destroyed
changed
another
List similarities between alternators and generators
Change mechanical energy into electrical energy
Produce electrical power through electromagnetic induction
Produce AC in the armature & change it to DC before it leaves the alternator
Have field windings and armatures
What is the main difference between alternators and generators?*
Generators have a stationary field and rotating armature
Alternators have a rotating field and stationary armature (coil)
List advantages of alternators versus generators*
Alternators supply power output through direct contact to the aircraft power whereas generators must supply power through commutator and brush assembly
Alternators do not require a rotating connection for the power output circuit whereas generators do
Alternators have a more stable connection than a generator because generators use a commutator and brush (unreliable connection)
All advantages to alternators are a direct result of the use of diodes for rectification
What are the parts of a DC alternator?*
Armature winding
Field winding
Rectifier assembly
Where is the current/voltage produced in alternators/generators?*
Armature (only difference is if it is spinning or not)
Describe the three-phase winding in an alternator
Stationary armature
Three output locations with each starting and ending at a ring terminal
What are the two common methods used to connect three-phase armature windings?
What is the difference between the two?
Delta winding (triangle)
Wye “Y” winding (Y shape)
Identical to each other in what the output is (three sine waves), the only difference is the shape
Describe the field winding in an alternator
Spins (rotates) within the armature winding
“Low” current winding
Receives voltage from the regulator
Connected through brushes and slip rings
What does the rectifier do in an alternator?*
What is full wave rectification*
The components which change AC to DC
Changes the “full” AC wave into ripple DC (only keep the peaks)
How is rectification done in an alternator?*
6 Silicon Diodes
3 positive, 3 negative
First set of diodes cleaves bottom portion of AC sine waves
Second set of diodes cleaves everything remaining but the peaks of the sine waves
Describe the symbol for an LED
A diode with + and - symbols and arrows coming off of the arrow to indicate light
Where are brushes found on alternators?*
Generators?*
Field winding
Commutator
Why would you use three-phase power?*
Power supplied remains constant
Greater power density (voltage) than a single phase circuit can at the same amperage
Smaller wires, lighter load, lower costs, fewer turns
