Unit 33 Delmar’s Standard Textbook of Electricity
1. What are the three general classifications of split-phase motors?
2. How many phases are required to produce a rotating magnetic field
3. How many degrees (physically) out of phase are the start and run windings in a
split-phase motor?
4. How are the start and run windings identified? (Visually)
5. What two factors determine synchronous speed in the stator?
6. What factors determine the starting torque of a resistance-start, induction-run
motor?
7. What is the approximate phase angle between the start and run windings in a
resistance-start, induction-run motor?
8. Where is the centrifugal switch connected in a resistance-start, induction-run
motor?
9. Why are starting relays used instead of a centrifugal switch on refrigeration and
air-conditioning equipment?
10. What is the advantage of a hot-wire starting relay?
11. Briefly, how does a current-relay operate?
12. What is a thermistor and what is unique about it?
13. Does a thermistor open the circuit to the start winding? Explain.
14. What is the phase relationship between the induced rotor voltage and the rotor
current for a squirrel-caged rotor?
15. What is the direction rotation if the start winding is kept out of the circuit when
power is applied to a split-phase motor?
16. Where is a capacitor connected in a capacitor-start, induction-run motor?
17. Why is the starting torque much higher in a capacitor-start, induction-run motor
than it is in a resistance-start, induction-run motor?
18. What precaution should be taken with a capacitor-start, induction-run motor?
19. Which terminals are typically switched to reverse a dual-voltage, split-phase
motor?
20. Where is the start winding connected for high-voltage when you have a dualvoltage run winding and a single-voltage start winding?
21. How is the direction of rotation determined for a motor without starting it?
22. Which motor is designed so the start winding is not removed from the circuit?
23. What type of capacitor is typically used for a capacitor-start, capacitor-run motor?
24. What is the benefit of leaving the capacitor connected in the motor circuit after
starting?
25. How does a potential starting relay operate?
26. What are the advantages of the shaded-pole induction motor?
27. What are the most common applications of shaded-pole motors?
28. At what point in the sine wave is there no voltage induced in the shaded-pole?
29. How many poles does a shaded-pole induction motor typically have?
30. How would you describe the torque of a shaded-pole motor?
31. How is a shaded-pole motor reversed? (Practically)
32. How is the speed changed in a multi-speed fan motor?
33. What does the selector switch control in a multi-speed fan?
34. What types of loads are best suited to multi-speed motors?
35. What are the three types of repulsion motors?
36. What principle does a repulsion motor operate on?
37. How is the rotor and brush assembly on a repulsion motor different from a DC
armature and brush assembly?
38. How is the number of poles for a rotor in a repulsion motor determined?
39. Where should the brushes be placed in relation to the poles for maximum torque?
40. How is the direction of rotation changed for a repulsion motor?
41. What is the single-phase motor with the highest starting torque?
42. What are the two types of repulsion-start, induction-run motors?
43. How do the two types of repulsion-start, induction-run motors become induction
run? (What action makes it happen)
44. How is a repulsion-induction motor different from a repulsion-start, induction-run
motor?
45. What is the advantage of the squirrel-cage winding in the rotor of the repulsioninduction motor?
46. Where are single-phase synchronous motors typically used?
47. What is another name for a single-phase synchronous motor?
48. What is the principle of operation for a stepping motor?
49. What determines the amount of angular rotation achieved each time a stepping
motor is stepped?
50. What is a permanent-magnet induction motor?
51. Which single-phase motor can be maintained in the stalled condition without
damage to the motor?
52. Which single-phase motor has a starting current that is the same as the running
current?
53. What is another name for the Universal Motor?
54. What is the purpose of the compensating winding in a universal motor?
55. Why is a universal motor “Universal”?
56. What are the two methods of connecting the compensating winding for a
universal motor?
57. How would you rate the speed regulation of a universal motor?
58. How is a universal motor reversed?