Power Electronics 3 Electrical Engineering MCQ Practice Quiz 6

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Created on July 19, 2021

Power Electronics 3 Electrical Engineering Practice Quiz 6

1 / 25

Any electrical signal present in a circuit other than the desired signal is known as____?

Noise

Distortion

Interference

All of these

2 / 25

In single phase VSI, the harmonic which is not present is____?

2nd

3rd

5th

7th

3 / 25

In the operation and control of both naturally commutated and forced commutated SCR base' converter, commutation plays an important role .The converters is / are____?

AC - DC

DC - DC

DC - AC

All of these

4 / 25

Double edge modulation eliminates certain harmonics when the reference is a_____?

Sine wave

Square wave

Triangular wave

Trapezoidal wave

5 / 25

The carrier which are commonly used in constant – frequency PWM is_____?

Sawtooth carrier

Inverted sawtooth carrier

Triangle carrier

All of these

6 / 25

In a three phase converter, the number of notches per cycle is_____?

One

Three

Six

Nine

7 / 25

The control method used for PWM dc - do converter is_____?

Voltage mode control

Current mode control

Hysteric control

All of these

8 / 25

The average value of the output voltage in a step - down dc chopper is given by____?

VO = Vs

VO = DVS

VO = V s/D

VO = V s/(1 - D)

9 / 25

Choppers is a______?

AC – DC converters

AC – AC converters

DC – AC converters

DC - DC converters

10 / 25

In BJT, switching losses occurs_____?

Only at turn – on

Only at turn – off

Both at turn on and off

None of these

11 / 25

DIAC are specifically designed to trigger_____?

TRIAC

SCR

GTO

Only (a) and (b)

12 / 25

Voltage commutation circuit can be converted into a current commutation by interchanging the positions of_____?

Diode and capacitor

Capacitor and SCR

Inductor and capacitor

Capacitor and load

13 / 25

For power output higher than 15 kW, the suitable rectifier is_____?

Single phase

3 phase

Poly phase

Only (b) and (c)

14 / 25

In a full wave rectifier, the rectification ratio is approximately equal to______?

0.61

0.71

0.81

0.91

15 / 25

In a single phase full wave rectifier, during blocking state the pea inverse voltage of diode is______?

V m

2 V m

V m /2

4 V m

16 / 25

A single phase ac – dc converter is also known as_____?

Rectifier

Regulator

Chopper

Inverter

17 / 25

In a silicon controlled rectifier, the load is connected_____?

Across anode

In series with anode

Across cathode

In series with cathode

18 / 25

Number of PN junction in an SCR____?

Two

Three

Four

Five

19 / 25

What is the advantage of HRC fuses over Rewireable fuses_____?

High speed operation

High rupturing capacity

No ageing effect

All of the above

20 / 25

The power demand can be estimated approximately by_____?

Load survey method

Mathematical method

Statistical method

Economic parameters

21 / 25

4 thyristors rated 200 V in series. The operating voltage of the string is 600 V. Derating factor of the string is_____?

0.75

0.7

0.2

0.25

22 / 25

Unipolar modulation is generally used in_____?

AC – AC converters

AC - DC converters

DC – AC converters

DC - DC converters

23 / 25

A string of n parallel SCRs is operated at 72 KA, the rating of each SCR is 1 KA. If derating factor of the string is 0.1. value of n will be____?