NEETS MODULE 5 CHAPTER 1 DIRECT CURRENT GENERATORS
Q1. Generators convert mechanical motion to electrical energy using what principle?
Q2. What rule should you use to determine the direction of induced emf in a coil?
Q3. What is the purpose of the slip rings?
Q4. Why is no emf induced in a rotating coil when it passes through the neutral plane?
Q5. What component causes a generator to produce dc voltage rather than ac voltage at its outputterminals?
Q6. At what point should brush contact change from one commutator segment to the next?
Q7. An elementary, single coil, dc generator will have an output voltage with how many pulsationsper revolution?
Q8. How many commutator segments are required in a two-coil generator?
Q9. How can field strength be varied in a practical dc generator?
Q10. What causes sparking between the brushes and the commutator?
Q11. What is armature reaction?
Q12. What is the purpose of interpoles?
Q13. What is the effect of motor reaction in a dc generator?
Q14. What causes copper losses?
Q15. How can eddy current be reduced?
Q16. Why are drum-type armatures preferred over the Gramme-ring armature in modern dcgenerators?
Q17. Lap windings are used in generators designed for what type of application?
Q18. What are the three classifications of dc generators?
Q19. What is the main disadvantage of series generators?
Q20. What term applies to the voltage variation from no-load to full-load conditions and is expressedas a percentage?
Q21. What term applies to the use of two or more generators to supply a common load?
Q22. What is the purpose of a dc generator that has been modified to function as an amplidyne?
Q23. What is the formula used to determine the gain of an amplifying device?
Q24. What are the two inputs to an amplidyne?
NEETS MODULE 5 CHAPTER 2 DIRECT CURRENT MOTORS
Q1. What factors determine the direction of rotation in a dc motor?
Q2. The right-hand rule for motors is used to find the relationship between what motorcharacteristics?
Q3. What are the differences between the components of a dc generator and a dc motor?
Q4. What causes counter emf in a dc motor?
Q5. What motor characteristic is affected by counter emf?
Q6. What is the load on a dc motor?
Q7. What is the main disadvantage of a series motor?
Q8. What is the main advantage of a series motor?
Q9. What advantage does a shunt motor have over a series motor?
Q10. Why is the Gramme-ring armature not more widely used?
Q11. How is the disadvantage of the Gramme-ring armature overcome in the drum-wound armature?
Q12. In a dc motor that must be able to rotate in both directions, how is the direction changed?
Q13. What is the effect on motor speed if the field current is increased?
Q14. Armature reaction in a dc motor causes a shift of the neutral plane in which direction?
Q15. What current flows in the interpole windings?
Q16. What is the purpose of starting resistors?
NEETS MODULE 5 CHAPTER 3 ALTERNATING CURRENT GENERATORS
Q1. Magnetic induction occurs when there is relative motion between what two elements?
Q2. What is the part of an alternator in which the output voltage is generated?
Q3. What are the two basic types of alternators?
Q4. What is the main advantage of the rotating field alternator?
Q5. Most large alternators have a small dc generator built into them. What is its purpose?
Q6. How are alternators usually rated?
Q7. What type of prime mover requires a specially designed high-speed alternator?
Q8. Salient-pole rotors may be used in alternators driven by what types of prime movers?
Q9. What does the term single phase indicate?
Q10. In single-phase alternators, in order for the voltages induced in all the armature windings to addtogether for a single output, how must the windings be connected?
Q11. What determines the phase relationship between the voltages in a two-phase ac generator?
Q12. How many voltage outputs are available from a two-phase three-wire alternator?
Q13. What is the relationship of the voltage at C in figure 3-7 to the voltages at A and B?
Q14. In a three-phase alternator, what is the phase relationship between the individual output voltages?
Q15. What are the two methods of connecting the outputs from a three-phase alternator to the load?
Q16. Ships’ generators produce 450-volt, three-phase, ac power; however, most equipment uses 117-volt, single-phase power What transformers and connections are used to convert 450-volt, threephasepower to 117-volt, single-phase power?
Q17. What two factors determine the frequency of the output voltage of an alternator?
Q18. What is the frequency of the output voltage of an alternator with four poles that is rotated at 3600rpm?
Q19. The variation in output voltage as the load changes is referred to as what? How is it expressed?
Q20. How is output voltage controlled in practical alternators?
Q21. What generator characteristics must be considered when alternators are synchronized for paralleloperation?
NEETS MODULE 5 CHAPTER 4 ALTERNATING CURRENT MOTORS
Q1. What are the three basic types of ac motors?
Q2. Series motors are generally used to operate what type of equipment?
Q3. Why are series motors sometimes called universal motors?
Q4. What determines the number of field poles required to establish a rotating magnetic field in amultiphase motor stator?
Q5. What is the angular displacement between field poles in a two-phase motor stator?
Q6. What is the major difference between a two-phase and a three-phase stator?
Q7. What requirement is the synchronous motor specifically designed to meet?
Q8. Why is the ac induction motor used more often than other types?
Q9. The speed of the rotor is always somewhat less than the speed of the rotating field. What is thedifference called?
Q10. What determines the amount of slip in an induction motor?
Q11. What type of ac motor is most widely used?
Q12. How do split-phase induction motors become self-starting?
Q13. Why are shaded-pole motors used to drive only very small devices?
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