Theory electronics

Question 1

Purpose of inductors in circuits

Answer 1

Filter harmonics

Question 2

Are rectifiers always in phase

Answer 2

Yes

Question 3

3 phase rectifiers current operates as a X step

Answer 3

6 step square wave

offset by 30 degrees to start, 30 off 120 on 60 off 120 negative 30 off

Question 4

Half converter leading or lagging

Answer 4

Always lagging

Question 5

What’s better a full converter or a half converter for PF

Answer 5

Better pf on half converter

Question 6

Is a half converter cheaper to build

Answer 6

Yes

Question 7

Full converter, what does it do

Answer 7

Variable voltage and worse pf correction

Question 8

When you fire later what happens?

Answer 8

THD becomes more distorted

Question 9

How does a full converter operate between 0 to 90 and 91 to 180°

Answer 9

0 to 90 rectification
91 to 180 inverting

Question 10

How many SCR in a full converter

Answer 10

4 scr

Question 11

How many SCR in a half converter

Answer 11

2 SCR 2 diode

Question 12

What type of single phase converter should be used to power a load that only requires rectifier mode

Answer 12

Half converter as it’s power factor is better and it’s less complex and cheaper, and would require no inversion

Question 13

What waveform does a rectifier create from it’s harmonics

Answer 13

Sinusoidal

Question 14

What are the benefits of using a 3 phase rectifier over a single phase

Answer 14

No triplens, better pf, no triplens content

Question 15

How do you provide variable vars to a system

Answer 15

Synchronous condenser

Question 16

What is a non linear load

Answer 16

A load that distorts the sinusoidal wave form IE electronics,

Question 17

Do harmonics create usable power

Answer 17

No, they create additional apparent power that cannot be used. Reducing power factor

Question 18

Do harmonic currents increase RMS current on conductors

Answer 18

Yes, harmonics create additional current that can’t be used as they are non linear (large VA without use)

Question 19

What is a linear load

Answer 19

Motors, heaters, non fluorescent lighting

Question 20

0% THD=

Answer 20

Perfect sinewave

Question 21

Which converter has a better power factor

Answer 21

Semi converter

Question 22

The THD for a single phase bridge rectifier with an adequately large inductor filter will always be

Answer 22

48.43%

Question 23

The Single Phase Bridge Rectifier is called a

Answer 23

2 pulse rectifier

Question 24

A transformer operating with higher than “X” THD should be derated

Answer 24

5%

Question 25

What are harmonics

Answer 25

Higher frequency currents or voltages that are a whole number multiple of the fundamental frequency (60hz)

Question 26

An inductor will have higher or lower impedance at higher frequencies?

Answer 26

Higher. XL= 2 x π x freq x L

XL INCREASES AND SO DOES FREQ

Question 27

Fournier analysis will be performed with

Answer 27

A spectrum analyzer, power quality analyzer

Question 28

Harmonics cause m² heating losses true or false

Answer 28

True

Question 29

Which harmonics add up in neutrals?

Answer 29

Triplens

Question 30

THD of 5 percent is usually ok for what loads?

Answer 30

High current loads

Question 31

What output can a full converter provide

Answer 31

0 to 100% voltage and positive or negative voltages
0 to 90 rectifier mode
91 to 180 inverter mode

Question 32

Does an inverter require an external DC source?

Answer 32

Yes

Question 33

Can a half converter invert power?

Answer 33

No

Question 34

What’s the advantage of a half converter over full converter

Answer 34

Half converter fundamental lags the firing angle by half so uses less vars