Chapter 17, The Synchronous Motor Video Solutions, Electricity 4: AC/DC Motors, Controls, and Maintenance

Problem 1

Fill in the answers to questions 1 through 9.
List the basic parts of a three-phase synchronous motor.
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Problem 2

Fill in the answers to questions 1 through 9.
What is an amortisseur winding?
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Problem 3

Fill in the answers to questions 1 through 9.
Explain the proper procedure to use in starting a synchronous motor.
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03:35

Problem 4

Fill in the answers to questions 1 through 9.
A three-phase synchronous motor with six stator poles and six rotor poles is operated
from a three-phase, 60 Hz line of the correct voltage rating. Determine the speed of the
motor._______________________________________________________
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Narayan Hari

Numerade Educator

Problem 5

Fill in the answers to questions 1 through 9.
How is a leading power factor obtained with a three-phase synchronous motor?
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Problem 6

Fill in the answers to questions 1 through 9.
What is the purpose of a rheostat in the separately excited DC field circuit of a synchro-
nous motor?
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Problem 7

Fill in the answers to questions 1 through 9.
How is the direction of rotation of a three-phase synchronous motor reversed?
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Problem 8

Fill in the answers to questions 1 through 9.
State two important applications for three-phase synchronous motors.
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Problem 9

Fill in the answers to questions 1 through 9.
What is a synchronous capacitor? __________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________

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Problem 10

Select the correct answer for the statements in items 10 through 14, and place the corresponding letter in the space provided. __________________________________
A synchronous motor must be started __________________________________
a. with full DC in the field circuit.
b. with weak DC in the field circuit.
c. as an induction motor.
d. when the power factor is low.

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Problem 11

Select the correct answer for the statements in items 10 through 14, and place the corresponding letter in the space provided. __________________________________
The speed of a synchronous motor ____________________________________
a. is constant from no load to full load.
b. drops from no load to full load.
c. increases from no load to full load.
d. is variable from no load to full load.

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Problem 12

Select the correct answer for the statements in items 10 through 14, and place the corresponding letter in the space provided. __________________________________
A synchronous motor with an underexcited DC field has _____________________
a. a leading power factor.
b. a lagging power factor.
c. less synchronous speed.
d. no effect.

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Problem 13

Select the correct answer for the statements in items 10 through 14, and place the corresponding letter in the space provided. __________________________________
The power factor of a synchronous motor can be varied by changing the ___________
a. brush polarity.
b. phase rotation.
c. speed of rotation.
d. field excitation.

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Problem 14

Select the correct answer for the statements in items 10 through 14, and place the corresponding letter in the space provided. __________________________________
A synchronous motor running on the three-phase line voltage serves the same function of power factor correction as ________________________________________
a. a bank of resistors.
b. a bank of capacitors.
c. an induction motor.
d. a wound-rotor motor.

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