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1. For a given number of poles, which of the following determines the speed of an AC motor?

Frame size

Frequency

Voltage

Current

Question 1 of 35

2. According to NEMA definitions, which of the following is a type of open motor?

Explosion-proof

Nonventilated

Weather-protected

Water-to-air-cooled

Question 2 of 35

3. Horsepower is used to rate the ________.

thermal protection of a motor

output capacity of a motor

length of operation of a motor

synchronous speed of a motor

Question 3 of 35

4. A three-phase synchronous motor has three stator windings that are ________.

180° apart

90° apart

45° apart

120° apart

Question 4 of 35

5. The primary method of varying the speed on a DC shunt motor is to adjust the voltage and current on the field winding or the ________.

armature

rheostat

controller

stator key

Question 5 of 35

6. The stationary magnet of a DC motor is represented by the ________.

commutator

rotor

field poles

armature

Question 6 of 35

7. According to NEMA definitions, which of the following is a type of totally enclosed motor?

Water-cooled

Guarded

Sealed windings

Drip-proof

Question 7 of 35

8. Which of the following is located on a motor's nameplate?

Synchronous speed

FLA rating

Lifting requirements

Circuit rating

Question 8 of 35

9. Which of the following motors operate on the principle of a rotating magnetic field?

Alternating current motors

Induction motors

Single-phase motors

Brushless DC motors

Question 9 of 35

10. Slip is best defined as ________.

the difference between the synchronous speed and the speed of the rotor in an induction motor

the rated output capacity of a motor

any current in excess of the rated current of equipment

the speed of the revolving field of the stator

Question 10 of 35

11. NEC Article 430 covers ________.

thermal protection requirements

the application and installation of motors

provisions for motor-driven equipment

general information on grounding

Question 11 of 35

12. Which motor should be used for applications that require frequent starts without overheating the motor?

Shunt motor

AC motor

Squirrel cage induction motor

Wound rotor induction motor

Question 12 of 35

13. The speed of a three-phase squirrel cage induction motor is controlled by the frequency of the applied voltage and ________.

armature current

voltage dropping resistors

the number of poles

full-load torque

Question 13 of 35

14. Any exposed live parts must be guarded if they are operating at ________.

50V or more between terminals

15V or more between terminals

600V or more between terminals

240V or more between terminals

Question 14 of 35

15. Which type of motor can be easily reversed by switching two of the leads?

Squirrel cage motor

Synchronous motor

Brushless DC motor

Three phase induction motor

Question 15 of 35

16. A motor enclosure that minimizes the entrance of rain and airborne particles to the electrical parts is considered ________.

weather-protected

drip-proof

sealed

dust-proof

Question 16 of 35

17. The wound rotor induction motor is used ________.

when reduced slip is required

to start low inertia loads

for speed control and to limit starting current

to increase power factor

Question 17 of 35

18. In a DC series motor, how much of its full-load torque is developed at starting?

250%

500%

50%

100%

Question 18 of 35

19. For a constant-torque load, the horsepower increases and decreases ________.

as the square of the speed

as the cube of the speed

in inverse proportion to the speed

in direct proportion to the speed

Question 19 of 35

20. In a split-phase motor, how much greater is the starting current when compared to the full-load current?

2 to 4 times

8 to 10 times

5 to 7 times

6 to 8 times

Question 20 of 35

21. Which of the following is true of shaded-pole motors?

They have a low starting torque, a low efficiency, and a high noise level.

They are small, inexpensive, and powerful.

They have a larger current, a lower total impedance, and a higher reactance.

They have a lower line current, are higher efficiency, and are very quiet.

Question 21 of 35

22. Which of the following are most likely to use dynamic braking?

Forklifts

Safety brakes

Circular saws

Machine tools

Question 22 of 35

23. A three-phase induction motor may have ________.

5 poles

1 pole

2 poles

7 poles

Question 23 of 35

24. The synchronous speed at which a four-pole, 60Hz induction motor operates is ________.

2,500 rpm

6,900 rpm

1,800 rpm

1,140 rpm

Question 24 of 35

25. Due to the absence of any moving electrical contacts, which type of motor should be used where the motor is exposed to flammable dust or gas?

Shunt motor

Squirrel cage induction motor

AC motor

Two loop DC motor

Question 25 of 35

26. Which of the following motors is used where the required starting torque is high and speed control is desirable?

Shunt

Series

Brushless

Compound

Question 26 of 35

27. DC injection braking is used on ________.

the rotors of series motors

compound DC motors where a slower stopping method is acceptable

the rotors of shunt motors

the stationary windings of AC motors

Question 27 of 35

28. How many motor designs does NEMA designate?

Question 28 of 35

29. The NEC® requires motor disconnecting means be ________.

8 feet or more above the floor

installed so access is limited to qualified persons

within sight of the controller location

guarded

Question 29 of 35

30. The most common service factor appearing on a motor's nameplate is ________.

1.15

2.15

1.5

Question 30 of 35

31. The value indicated in rpm on the nameplate is the ________.

duty rating

power factor

rated horsepower

rated full-load speed

Question 31 of 35

32. The capacitor-start motor is the single-phase motor type that has the ________.

highest noise level

highest starting torque

lowest efficiency

lowest starting torque

Question 32 of 35

33. Which of the following motors is the best installation choice for an application requiring adjustable speeds?

Capacitor-start

Split-phase

Synchronous

Question 33 of 35

34. A wound rotor motor has been recently put back into service but is now rotating in the wrong direction. After examining the motor, you find that lead L1 is connected to T2, L2 to T3, and L3 to T1. To correct the rotation, you should:

Connect L1 to T1, L2 to T3, and L3 to T2.

Connect L1 to T1, L2 to T2, and L3 to T3.

Reverse phase connections between the wound rotor and the resistor bank.

Connect L2 to T1, L3 to T2, and L1 to T3.

Question 34 of 35

35. Which of the following motors provides constant speed from no-load conditions to full-load conditions?

Series DC

Synchronous

Squirrel cage induction

Shunt DC

Question 35 of 35

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