ENGINE ELECTRICAL SYSTEMS Flashcards
How would you seat newly installed generator brushes to the commutator?
When new brushes are installed in a generator, the face of the brushes must be shaped to
provide an area of maximum contact with the commutator. To seat the brushes, use fine grain
sandpaper placed around the commutator with the sanding surface facing outward. Turn the
armature in a normal direction of rotation until the face of the brushes is properly contoured.
Remove the sandpaper and blow out any residue with compressed air.
Where is the generator rating and performance data located?
It is stamped on the data plate attached to the generator
What units make up a DC generator three-unit regulator?
The voltage regulator, the current limiter, and the reverse current cutout
What method is used to control the voltage of an aircraft alternator?
The voltage regulator
What determines the frequency of the voltage of an alternator?
The frequency depends upon the speed of rotation of the rotor and the number of poles.
How is alternator frequency maintained?
By installing a constant speed drive (CSD) unit between the engine and the alternator.
What are the three basic types of DC motors?
Series motors, shunt motors, and compound motors
Name the parts of a DC motor?
The armature, the field, the brushes, and the frame.
What is a starter-generator system, used on many turbine engines?
The system uses a starter-generator which operates as a starter motor to drive the engine
during starting, and after the engine has reached a self-sustaining speed, it operates as a
generator to supply the electrical system power.
What is the American Wire Gauge (AWG) system of designating electrical wire size?
A gauge number is assigned the wire according to its cross-sectional area. The smaller the
gauge number, the larger the wire.
What is open wiring?
Open wiring is any wire, wire group, or wire bundle not enclosed in conduit.
What method is used to control the voltage of DC aircraft generators?
The only practical means of regulating generator voltage is to control the strength of the
magnetic field. Field strength is determined by the amount of current flowing through the field
coils, and the current is controlled by placing some form of variable or intermittent resistance in
the external field circuit of the generator.
What are the causes of excessive arcing at the generator brushes?
Arcing can be caused by a commutator that is dirty, rough, or out of round. A more common
cause of arcing is worn or binding brushes or the brush spring tension too low.
When installing single wires or wire bundles, how much slack is normally allowed between supports?
Slack between supports should normally not exceed one-half inch.
What precaution should be taken when running wires close to heating ducts or exhaust stacks?
The wires should be insulated with a high-temperature material.
