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24 Cards in this Set
- Front
- Back
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Q1. Generators convert mechanical motion to electrical energy using what principle?
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A1. Magnetic induction.
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Q2. What rule should you use to determine the direction of induced emf in a coil?
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A2. The left-hand rule for generators.
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Q3. What is the purpose of the slip rings?
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A3. To conduct the currents induced in the armature to an external load.
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Q4. Why is no emf induced in a rotating coil when it passes through the neutral plane?
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A4. No flux lines are cut.
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Q5. What component causes a generator to produce dc voltage rather than ac voltage at its output
terminals? |
A5. A commutator
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Q6. At what point should brush contact change from one commutator segment to the next?
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A6. The point at which the voltage is zero across the two segments.
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Q7. An elementary, single coil, dc generator will have an output voltage with how many pulsations
per revolution? |
A7. Two.
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Q8. How many commutator segments are required in a two-coil generator?
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A8. Four
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Q9. How can field strength be varied in a practical dc generator?
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A9. By varying the input voltage to the field coils.
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Q10. What causes sparking between the brushes and the commutator?
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A10. Improper commutation.
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Q11. What is armature reaction?
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A11. Distortion of the main field due to the effects of armature current
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Q12. What is the purpose of interpoles?
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A12. To counter act armature reaction.
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Q13. What is the effect of motor reaction in a dc generator?
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A13. A force which causes opposition to applied turning force.
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Q14. What causes copper losses?
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A14. Resistance in the armature coils, which increases with temperature.
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Q15. How can eddy current be reduced?
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A15. By laminating the core material.
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Q16. Why are drum-type armatures preferred over the Gramme-ring armature in modern dc
generators? |
A16. Drum-type armatures are more efficient, because flux lines are cut by both sides of each coil.
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Q17. Lap windings are used in generators designed for what type of application?
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A17. Higher load currents are possible.
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Q18. What are the three classifications of dc generators?
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A18. Series-wound, shunt-wound, and compound-wound.
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Q19. What is the main disadvantage of series generators?
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A19. Output voltage varies as the load varies.
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Q20. What term applies to the voltage variation from no-load to full-load conditions and is expressed
as a percentage? |
A20. Voltage regulation.
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Q21. What term applies to the use of two or more generators to supply a common load?
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A21. Parallel operation.
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Q22. What is the purpose of a dc generator that has been modified to function as an amplidyne?
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A22. It can serve as a power amplifier.
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Q23. What is the formula used to determine the gain of an amplifying device?
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A23. Gain = output ÷ input.
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Q24. What are the two inputs to an amplidyne?
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A24. The mechanical force applied to turn the amplidyne, and the electrical input signal.
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