Question 1

A_________ is used to smooth the pulsations caused by a bridge rectifier.

Accepted Answer

A)   phasor
B)   filter capacitor
C)   transistor
D)   diodeE) None of the above
F) A) and D)

Question 2

The phasor rotation of a negative harmonic causes an induction motor to produce_________ .

Accepted Answer

A)   positive feedback
B)   a high magnetic field
C)   less torque
D)   more torqueE) A) and C)
F) None of the above

Question 3

Harmonic currents in the neutral conductor induce_________ currents into the communication cable.

Accepted Answer

A)   high-frequency
B)   low-frequency
C)   no new
D)   constantE) B) and D)
F) B) and C)

Question 4

Ammeters that respond to the average value convert the alternating current into direct current. This value must be increased by a factor of_________ to change the average reading into the rms value for a sine wave current.

Accepted Answer

A)   0.651
B)   1.111
C)   1.414
D)   1.730E) B) and C)
F) All of the above B

Question 5

The most accurate method for determining whether there is a harmonics problem is to use a(n) _________ .

Accepted Answer

A)   transformer
B)   average value ammeter
C)   true rms ammeter
D)   harmonic analyzerE) All of the above
F) A) and D)

Question 6

What are some devices that are responsible for harmonics?

Accepted Answer

Harmonics on single-phase power lines ar...

Question 7

Transformers are typically designed for _________-hertz operation.

Accepted Answer

A)   50
B)   60
C)   100
D)   120E) All of the above
F) A) and D)

Question 8

The instantaneous peak value of current is equal to the rms value multiplied by _________.

Accepted Answer

A)   0.651
B)   1.111
C)   1.414
D)   1.730E) B) and C)
F) A) and C)

Question 9

Harmonics are voltages or currents that operate at a frequency that is the_________ fundamental power frequency.

Accepted Answer

A)   a multiple of
B)   a divisor of
C)   double
D)   within 10 Hz ofE) C) and D)
F) A) and D)

Question 10

What problems do triplens pose for neutral bus ducts?

Accepted Answer

Triplen harmonic currents can also cause...

Question 11

What problems are caused by harmonics in circuit breakers?

Accepted Answer

Thermomagnetic circuit breakers use a bi...

Question 12

Harmonics called _________have a zero sequence.

Accepted Answer

A)   positives
B)   negatives
C)   doublens
D)   triplensE) A) and C)
F) B) and C)

Question 13

Harmonics are produced by loads that draw current in_________ .

Accepted Answer

A)   a sine wave
B)   a linear manner
C)   a continuous manner
D)   pulsesE) None of the above
F) A) and B)

Question 14

One way to deal with harmonic problems is to install_________ a neutral conductor.

Accepted Answer

A)   larger
B)   smaller
C)   common
D)   triplenE) All of the above
F) B) and D) A

Question 15

It is necessary to use an ammeter that responds to _________current when making a check for harmonics.

Accepted Answer

A)   single-phase
B)   rectified
C)   true rms
D)   averageE) All of the above
F) A) and B) C

Question 16

To minimize interference, communication cables are run as close to the _________conductor as possible.

Accepted Answer

A)   positive phase
B)   negative phase
C)   triplen
D)   neutralE) None of the above
F) A) and B)

Question 17

THDF stands for_________ .

Accepted Answer

A)   triplen harmonic derating factor
B)   triplen harmonic desensitizing field
C)   transformer honed resultant field
D)   transformer harmonic derating factorE) B) and C)
F) A) and C)

Question 18

What steps should you follow when determining whether there are harmonic problems in single-phase systems?

Accepted Answer

There are several steps that can be foll...

Question 19

How are harmonics classified?

Accepted Answer

Harmonics are classified by name, freque...

Question 20

A ratio of _________between measurements made with a true rms ammeter and an average value ammeter indicates no harmonic distortion.

Accepted Answer

A)   0.5
B)   0.75
C)   0.833
D)   1.0E) A) and B)
F) B) and D)

Exam 21: Harmonics

A_________ is used to smooth the pulsations caused by a bridge rectifier.

Correct AnswerverifiedShow Answer

The phasor rotation of a negative harmonic causes an induction motor to produce_________ .

Correct AnswerverifiedShow Answer

Harmonic currents in the neutral conductor induce_________ currents into the communication cable.

Correct AnswerverifiedShow Answer

Ammeters that respond to the average value convert the alternating current into direct current. This value must be increased by a factor of_________ to change the average reading into the rms value for a sine wave current.

Correct AnswerverifiedB

The most accurate method for determining whether there is a harmonics problem is to use a(n) _________ .

Correct AnswerverifiedShow Answer

What are some devices that are responsible for harmonics?

Correct AnswerverifiedHarmonics on single-phase power lines ar...View AnswerShow Answer

Transformers are typically designed for _________-hertz operation.

Correct AnswerverifiedShow Answer

The instantaneous peak value of current is equal to the rms value multiplied by _________.

Correct AnswerverifiedShow Answer

Harmonics are voltages or currents that operate at a frequency that is the_________ fundamental power frequency.

Correct AnswerverifiedShow Answer

What problems do triplens pose for neutral bus ducts?

Correct AnswerverifiedTriplen harmonic currents can also cause...View AnswerShow Answer

What problems are caused by harmonics in circuit breakers?

Correct AnswerverifiedThermomagnetic circuit breakers use a bi...View AnswerShow Answer

Harmonics called _________have a zero sequence.

Correct AnswerverifiedShow Answer

Harmonics are produced by loads that draw current in_________ .

Correct AnswerverifiedShow Answer

One way to deal with harmonic problems is to install_________ a neutral conductor.

Correct AnswerverifiedA

It is necessary to use an ammeter that responds to _________current when making a check for harmonics.

Correct AnswerverifiedC

To minimize interference, communication cables are run as close to the _________conductor as possible.

Correct AnswerverifiedShow Answer

THDF stands for_________ .

Correct AnswerverifiedShow Answer

What steps should you follow when determining whether there are harmonic problems in single-phase systems?

Correct AnswerverifiedThere are several steps that can be foll...View AnswerShow Answer

How are harmonics classified?

Correct AnswerverifiedHarmonics are classified by name, freque...View AnswerShow Answer

A ratio of _________between measurements made with a true rms ammeter and an average value ammeter indicates no harmonic distortion.

Correct AnswerverifiedShow Answer

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B

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Harmonics on single-phase power lines ar...
View Answer

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Triplen harmonic currents can also cause...
View Answer

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Thermomagnetic circuit breakers use a bi...
View Answer

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A

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C

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There are several steps that can be foll...
View Answer

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Harmonics are classified by name, freque...
View Answer

Correct Answer
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