Harmonics

Question 1

In an AC electrical system, ___ are a distortion of the sisusodial voltage and currents

Answer 1

Harmonics

Question 2

As harmonics number increases their associated ___ ___

Answer 2

Frequency increases

Question 3

Harmonics found on electrical systems can be?

Answer 3

Even or odd.

Mostly odd

Question 4

Odd harmonics are generated by?

Answer 4

Non linear loads

Question 5

What causes additional heating in an electrical system and reduces efficiency?

Answer 5

Odd harmonics

Question 6

What is a set of harmonics that present additional challenges in the phase systems?

Answer 6

Triplin harmonics

They are multiples of threes

Question 7

Harmonics in power systems are relevant up to the __ harmonic

Answer 7

50th harmonic (3000 Hz)

Question 8

What happens when more and more harmonics are added to the fundamental frequency?

Answer 8

The sine wave becomes squarer

Question 9

How do you calculate the sum of harmonics?

And the total effective value of the system?

Answer 9

For the total effective value the system you use the same calculation and add on the voltage of the system squared.

Question 10

How do you calculate total harmonic distortion?

Answer 10

Eh = total harmonic V
Ef = fundamental V

Question 11

What is the ideal value for the crest factor of a sin wave?

Answer 11

1.414

Question 12

Do all electrical systems possess harmonics?

Answer 12

Yes

Question 13

Any device that has its impedance effected by the voltage applied is?

Answer 13

A non linear impedance

Question 14

Arcing equipment in electrical systems can be a significant source of harmonics.

What are 3 common arcing equipments?

Answer 14

Arc furnaces

Welding machines

Electric discharge machining

Question 15

When either voltage or current harmonics are present what happens?

Answer 15

One will caus the other to occur in the system

Question 16

Harmonic distortion in systems can lead to?

Answer 16

Electromagnetic interference

Question 17

Voltage distortions of __ to __ can caus excessive RMS currents of __ to __

Answer 17

5% to 10%

10% - 50%

Question 18

What are the primary effects of voltage harmonics on electrical equipment?

Answer 18

Can caus insulation damage

Question 19

How do harmonics affect the power factor of an electrical system?

Answer 19

It increases the reactive power which lowers the power factor

Question 20

Measuring harmonics.
What do the ranges mean?

Answer 20

Voltage
0-5% - normal
5-8% - significant
8% and up - major

Current
0-10% - normal
10-50% significant
50% and up - major

Question 21

What are two types of harmonic filters?

Answer 21

Passive

Active

Question 22

Passive filters consist of?

Answer 22

Inductor

Capacitors

Resistors

Question 23

What are 3 types of active filters

Answer 23

Series

Shunt

Hybrid

Question 24

What are the 3 transformer connections used for harmonic control?

Answer 24

Delta wye

Wye delta

Zig zag connection

Question 25

Delta wye and wye delta are highly effective at blocking?

Answer 25

The passage of triplin harmonics

Question 26

Zig zag transformers are highly effective in?

Answer 26

Managing triplin harmonics

Question 27

How can harmonics be measured in a power system?

Answer 27

Harmonic analyzers Power quality analyzers

Question 28

What is a rating that indicates a transformers ability to handle harmonic loads without overheating or being damaged?

Answer 28

K - factor

Question 29

Triplen harmonics are particularly problematic in what type of system connection?

Answer 29

3 phase wye

Question 30

What device is known to create significant harmonics in electrical systems?

Answer 30

VFDs

Question 31

How are active shunt filters typically installed?

Answer 31

In parallel with the load

Question 32

Which type of filter is specifically engineered to interact with higher order harmonics?

Answer 32

C-type filter

Question 33

A 336 uF capacitor is connected to a 240 VRMS: 60 Hz supply. The 5th harmonic has voltage of 24 VRMs, the current produced by the capacitor at this harmonic will be __ A

Answer 33

15.20045 To find the current = e ÷ ohms. Or the volts in this question devided by the answer in this question

Question 34

What is the inductance reactance calculation?

Answer 34