1. The dual-voltage nine-lead three-phase motor will be connected (internally) either wye or delta (page 275). T_ F
2. In-plant power problems will cause immediate motor failures (page 275).
3. Name two in-plant problems that will cause the immediate failure of a three-phase motor (page 275).
4. The ends of each phase are joined internally in a wye-connected motor.
(pages 275-276) T_ F
5. The delta connection has each phase end connected to the start of the next phase (pages 278-281). T_ F
6. The delta connection and multicircuit design allow the use of smaller wire in the winding coils (pages 281-283). T_ F
7. Why should the motor be assembled when identifying unmarked leads (pages 285-286)?
8. Why is there no voltage detected in the idle phase during the unmarked lead test (pages 285-288)?
9. The delta connection will have three sets of three leads that light to each other (page 288). T_ F
10. When testing for unmarked leads, an analog DC voltmeter shows a deflection, and works better than a digital meter (pages 292-293).
11. The largest amount of resistance to current flow in a three-phase winding is furnished by inductive reactance (pages 293-294). T_ F
12. Circulating current within a short can char and melt the turns within the short (page 294). T_ F
13. A phase-to-phase short is usually obvious, and requires replacing or rewinding the motor (pages 295-296). T_ F
14. Name three causes of an open winding (page 298).
15. A three-phase motor running on single phase will have (page 298)
a. full power.
b. 2/3 power.
c. 1/2 power.
16. A motor that failed from a single-phase line condition—with one phase burned and two phases near normal—is connected (page 300)
a. wye.
b. delta.
17. The first test (from winding to frame) on motors that have been subjected to water should be done with an ohmmeter (page 300).
18. All motors that have been submerged in water must be rewound (pages 300-301). T_ F
19. An ohmmeter will always detect a grounded motor winding by testing at the motor’s disconnect or control (page 301). T_ F
20. All rotor problems cause instant motor failure (page 302). T_ F
21. A sign of misaligned rotor/stator iron is high no-load amperes (page 303).
22. What is an easy way to detect electrically caused vibration (pages 303-304)?
23.
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An out-of-round rotor that has been “skimmed” with a lathe has no effect on a motor’s performance (page 303). T_ F
24. A rotor that is loose on its shaft should be replaced (pages 303-304).
25. Overvoltage will affect some motors more than others (pages 304-305).
26. What is the allowable NEMA standard deviation (pages 304-305)?
27. Most of a motor’s efficiency loss is in the air gap (page 305). T_ F 
28. Within the allowable 10 percent voltage variation, low voltage overheats a (fully loaded) motor more than high voltage does (pages 305-306).
29. Operating on low voltage is similar to overloading a normally loaded motor (page 306). T_ F
30. Unbalanced voltage is always caused by a faulty transformer, and is a problem the power supplier has to fix (pages 306-308). T_ F
31. Unbalanced voltage will cause immediate winding failure in a threephase motor (page 307). T_ F
32. Unbalanced voltage affects only wye-connected motors (page 308).
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33. High-resistance connections occur more often in a motor supply line than in that of a lighting circuit (page 308). T_ F
34. Frequent motor starting increases terminal connection problems
(page 308). T_ F
35. A motor that has oversized supply lines can’t be protected from overloads (page 308). T_ F
36. Tightening the terminals in a motor’s disconnect switch should be part of the scheduled motor maintenance (page 308). T_ F
37. Motor lead lugs and lead wire can be undersized because they carry current such a small distance (pages 308-309). T_ F
38. Undersized lead lugs will eventually overheat and char, causing an open or high-resistance circuit (page 309). T_ F
39. A tachometer can quickly determine if a motor is overloaded
(pages 309-310). T_ F
40. If a motor overheats because of its stop/ start cycle, but not its load, it’s better to install a larger motor than to use forced ventilation (page 310).
41. Running a motor with no load is the best way to uniformly cool down a motor (page 311). T_ F
42. Across-the-line starting and reduced-power starting produce approximately the same amount of internal heat (page 312). T_ F
43. A motor
run with shorted turns in its winding (pages 312-313).
a. may
b. won’t
44. Shorted turns can sometimes be detected by a ringing sound
(pages 312-313). T_ F
45. An uneven air gap will destroy a winding immediately (page 313).
46. A motor with a high service factor can run continuously at this value
(page 313). T_ F
47. If a motor connected for high voltage is run on low voltage, it will produce only half its rated horsepower (page 314). T_ F
48. A motor rated for 250 volts can operate on 208 volts if its full-load speed is close to its nameplate RPM (page 314). T_ F
49. A four-pole motor designed for 50 Hz—operating on 60 Hz—will run 300 RPM (pages 314-315)
a. faster.
b. slower.
50. A 50-Hz motor has
on 60 Hz (pages 314-315).
a. more power
b. less power
51. A 60-Hz motor has
on 50 Hz (page 315).
a. more power
b. less power
52. All rotor problems cause a fully loaded motor to lose power and run hot
(page 315). T_ F
53. Most large motors need 18 inches of clearance, for unrestricted ventilation (page 316). T_ F