Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
Generators convert mechanical motion to electrical energy using what principle?
|
Magnetic induction.
|
|
What rule should you use to determine the direction of induced emf in a coil?
|
The left-hand rule for generators.
|
|
What is the purpose of the slip rings?
|
To conduct the currents induced in the armature to an external load.
|
|
Why is no emf induced in a rotating coil when it passes through the neutral plane?
|
No flux lines are cut.
|
|
What component causes a generator to produce dc voltage rather than ac voltage at its output
terminals? |
A commutator
|
|
At what point should brush contact change from one commutator segment to the next?
|
The point at which the voltage is zero across the two segments.
|
|
An elementary, single coil, dc generator will have an output voltage with how many pulsations
per revolution? |
Two.
|
|
How many commutator segments are required in a two-coil generator?
|
Four
|
|
How can field strength be varied in a practical dc generator?
|
By varying the input voltage to the field coils.
|
|
What causes sparking between the brushes and the commutator?
|
Improper commutation.
|
|
What is armature reaction?
|
Distortion of the main field due to the effects of armature current.
|
|
What is the purpose of interpoles?
|
To counter act armature reaction.
|
|
What is the effect of motor reaction in a dc generator?
|
A force which causes opposition to applied turning force.
|
|
What causes copper losses?
|
Resistance in the armature coils, which increases with temperature.
|
|
How can eddy current be reduced?
|
By laminating the core material.
|
|
Why are drum-type armatures preferred over the Gramme-ring armature in modern dc
generators? |
Drum-type armatures are more efficient, because flux lines are cut by both sides of each coil.
|
|
Lap windings are used in generators designed for what type of application?
|
Higher load currents are possible.
|
|
What are the three classifications of dc generators?
|
Series-wound, shunt-wound, and compound-wound.
|
|
What is the main disadvantage of series generators?
|
Series-wound, shunt-wound, and compound-wound.
|
|
What term applies to the voltage variation from no-load to full-load conditions and is expressed
as a percentage? |
Voltage regulation.
|
|
What term applies to the use of two or more generators to supply a common load?
|
Parallel operation.
|
|
What is the purpose of a dc generator that has been modified to function as an amplidyne?
|
It can serve as a power amplifier.
|
|
What is the formula used to determine the gain of an amplifying device?
|
Gain = output ÷ input.
|
|
What are the two inputs to an amplidyne?
|
The mechanical force applied to turn the amplidyne, and the electrical input signal.
|
|
is the voltage applied to the main field windings.
|
FIELD EXCITATION
|