Aircraft DC Generation Systems Flashcards
Magnets produce a magnetic field. The force produced by the magnetic field is measured by the ______ that have developed. The more______ produced, the stronger the magnetic field and the higher the induction.
Magnets produce a magnetic field. The force produced by the magnetic field is measured by the density of flux lines that have developed. The more flux lines produced, the stronger the magnetic field and the higher the induction.
Moving a conductor through the stationary magnetic field can _______. Rotating the magnetic field around a stationary conductor can also________.
induce current.
Moving a conductor through a magnetic field generates _______.
Moving a conductor through a magnetic field generates alternating current (AC).
In this example of one rotation, rotating the conductor a 1/4 turn cuts through the maximum number of flux lines, inducing a voltage. As the conductor rotates 1/2 turn, fewer flux lines are cut. The induced voltage reduces to zero. Continuing the rotation, a 3/4 turn again induces maximum voltage; however, the polarity is reversed. Completing the rotation, the induced voltage returns to zero. This full rotation produces a _______.
sine wave
DC generators are actually AC generators with some internal modifications. Instead of taking the current from the loops through slip rings and brushes producing a sine wave, the DC generator employs a mechanical rectifier called a ______.
commutator.
A ________ consists of wedge-shaped segments of copper that are insulated from touching each other by thin sheets of mica. The ______ is designed to accept the current produced in the loops at specific intervals, thus removing the negative side of the sine wave.
A commutator
As the green side of the loop begins to cut the lines of flux, a positive current is produced and routed to the green wedge of the commutator. The commutator transfers the current, via _______, to the output. When the loop reaches 180°, again, no lines are cut and no current is present.
Continued loop rotation cuts the lines of flux on the yellow side of the loop, producing a positive current. The yellow side commutator is in contact with the brush, which routes another positive pulse to the load. Notice that the brush is always in contact with the positive commutator wedge creating pulsing positive current flow.
As the green side of the loop begins to cut the lines of flux, a positive current is produced and routed to the green wedge of the commutator. The commutator transfers the current, via brushes, to the output. When the loop reaches 180°, again, no lines are cut and no current is present.
Continued loop rotation cuts the lines of flux on the yellow side of the loop, producing a positive current. The yellow side commutator is in contact with the brush, which routes another positive pulse to the load. Notice that the brush is always in contact with the positive commutator wedge creating pulsing positive current flow.
Which component of the DC alternator produces the AC output sent to the rectifier?
Stator
Rotor
Armature
Slip rings
Stator
What makes a starter generator unique from a standard DC generator?
The starter generator provides power to the AC power distribution system.
The starter generator has a start sequence commutator.
The starter generator has an extra set of field windings that act like a motor.
The starter generator has an extra rotor that acts like a motor.
The starter generator has an extra set of field windings that act like a motor.
What is the purpose of the slip rings and brushes in a DC alternator?
Transfer AC from the rotor to the rectifier
Transfer AC from the stationary regulator to the rotor
Transfer AC from the stationary regulator to the commutator
Transfer DC from the stationary regulator to the rotor
Transfer DC from the stationary regulator to the rotor
Which part of the DC generator produces the electromagnetic field?
Commutator
Field frame
Armature
Housing
Field frame
How does the regulator increase the DC alternator output?
Sends a signal to increase the rotor rpm
Decreases the DC directed to the rotor to decrease the magnetic field current
Sends a signal to decrease the rotor rpm
Increases the DC directed to the rotor to increase the magnetic field current
Increases the DC directed to the rotor to increase the magnetic field current
What effects will compressing the carbon pile have on the output of the generator?
Field coil circuit resistance increases, field current decreases, output voltage decreases.
Field coil circuit resistance decreases, field current increases, output voltage increases.
Field coil circuit resistance decreases, field current decreases, output voltage decreases.
Field coil circuit resistance increases, field current increases, output voltage increases.
Field coil circuit resistance decreases, field current increases, output voltage increases.
What is NOT a function of the alternator control unit?
Protect system from an over-voltage condition
Protect the circuit from an over-frequency condition
Protect the alternator from a reverse current condition
Protect the starting circuitry
Protect the circuit from an over-frequency condition
Brushes used beyond their recommended service life can cause _______.
shorting of the stator
a voltage increase in the magnetic field coils
irreparable damage to the slip rings
shorting of the field housing
irreparable damage to the slip rings
