Power Electronics MCQ Questions And Answers

Power Electronics MCQ Questions And Answers. Important Multiple Choice Questions and Answers on the topic of Power Electronics

 

Power Electronics MCQ Questions And Answers

 

SCR will be turned off when anode current is ?

A. < latching current but greater than holding current and gate signal is 0
B. less than holding current
C. < latching current but greater than holding current and gate signal is presen
D. both (A) and (B)

View Answer

D. both (A) and (B)

 

Materials used in heat sink should have ?

A. high thermal conductivity
B. large surface area
C. high melting point
D. All of these

View Answer

D. All of these

 

IGBT combines the advantages of ?

A. BJTs and SITs
B. BJTs and MOSFETs
C. SITs and MOSFETs
D. None of these

View Answer

B. BJTs and MOSFETs

 

How can we protect SCR from thermal conditions ?

A. Use of snubber circuit
B. Using heat sink
C. Using CB and fuse
D. Using equalizing circuit

View Answer

B. Using heat sink

 

The effects of EMI can be reduced by ?

A. Suppressing emissions
B. Reducing the efficiency of the coupling path
C. Reducing the susceptibility of the receptor
D. All of these

View Answer

D. All of these

 

After proper turn on of thyristor ?

A. gate signal is always present
B. gate signal must be removed
C. gate signal should present but can be removed
D. none of the above

View Answer

B. gate signal must be removed

 

Thermal voltage VT can be given by ?

A. Kq/T
B. KT/q
C. qT/K
D. (K2/q)(T + 1/T – 1)

View Answer

B. KT/q

 

Electrical power output in a D.C. generator is equal to ?

A. Electrical power developed in armature – copper losses
B. Mechanical power input – iron and friction losses
C. Electrical power developed in armature – iron and copper losses
D. Mechanical power input – iron and friction losses – copper losses

View Answer

D. Mechanical power input – iron and friction losses – copper losses

 

Power Electronics MCQ Questions And Answers

 

In a push – pull converter, the filter capacitor can be obtained as ?

A. Cmin = V / ( Vr L f2 )
B. Cmin= ( 1 – D ) V / ( Vr L f2 )
C. Cmin= ( 1 – 2 D ) V / 32 ( Vr L f2 )
D. Cmin= ( 1 – 2 D ) V / 42 ( Vr L f2 )

View Answer

C. Cmin= ( 1 – 2 D ) V / 32 ( Vr L f2 )

 

A MOSFET, for its conduction uses ?

A. Only minority carriers
B. Only majority carriers
C. Both minority and majority carriers
D. None of these

View Answer

B. Only majority carriers

 

An RC snubber network used in BJT ?

A. Divert the collector current during turn – off
B. Improves the reverse bias safe operating area
C. Dissipates a fair amount of switching power
D. All of these

View Answer

D. All of these

 

The output current in PWM DC – DC converters is equal to ?

A. Average value of the output inductor current
B. Product of an average inductor current and a function of duty ratio
C. Either A. or B
D. None of these

View Answer

C. Either A. or B

 

In a lossless inverter, the average power absorbed in one period by the load must be ?

A. Equal to the average power supplied by the dc source
B. Greater than the average power supplied by the dc source
C. Lesser than the average power supplied by the dc source
D. Equal to the average power supplied by the ac source

View Answer

A. Equal to the average power supplied by the dc source

 

A TRIAC can be turned on with ?

A. Positive voltage at the gate terminal
B. Negative voltage at the gate terminal
C. Either (a) or (b)
D. None of these

View Answer

C. Either (a) or (b)

 

Ripple factor is the ratio of ?

A. Rms value of the ac component of load voltage to the dc voltage
B. Average value of the ac component of load voltage to the peak value of voltage
C. Average value of the dc component of load voltage to the ac voltage
D. Peak value of the dc component of load voltage to the ac voltage

View Answer

A. Rms value of the ac component of load voltage to the dc voltage

 

The on – state voltage drop of IGBT consists of ?

A. Drop across the collector junction
B. Drop across the drift region
C. Drop across MOSFET portion
D. All of these

View Answer

D. All of these

 

Power Electronics MCQ Questions And Answers

 

An ideal diode is ?

A. Unidirectional
B. Bidirectional
C. Fixed voltage polarity
D. Only (a) and (c)

View Answer

D. Only (a) and (c)

 

The maximum firing angle in the half wave controlled regulator is ?

A. 180 degree
B. 190 degree
C. 200 degree
D. 210 degree

View Answer

D. 210 degree

 

In a phase controlled 3 phase ac voltage controller, the harmonic present is ?

A. 2nd
B. 3rd
C. 5th
D. 7th

View Answer

A. 2nd

 

The advantage of using freewheeling diode in half controlled bridge converter is that ?

A. There is always a path for the dc current independent of the ac line
B. There is always a path for the ac current independent of the ac line
C. There is always a path for the dc current dependent of the ac line
D. There is always a path for the ac current independent of the ac line

View Answer

A. There is always a path for the dc current independent of the ac line

 

Advantages of HVDC transmission over AC system is ?

A. Reversal of power can be controlled by firing angle
B. Very good dynamic behavior
C. They can link two AC system operating unsynchronized
D. All of these

View Answer

D. All of these

 

Single phase VSI are mainly used in ?

A. Power supplies
B. Ups
C. Multilevel configuration
D. All of these

View Answer

D. All of these

 

In a three phase voltage source inverters ?

A. Only amplitude of voltage is controllable
B. Only phase is controllable
C. Both amplitude and phase is controllable
D. Amplitude, phase and frequency of voltages should always be controllable

View Answer

D. Amplitude, phase and frequency of voltages should always be controllable

 

In BJT, switching losses occurs ?

A. Only at turn – on
B. Only at turn – off
C. Both at turn on and off
D. None of these

View Answer

C. Both at turn on and off

 

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

A. V 0 = V s
B. V 0 = D V s
C. V 0 = V s / D
D. V 0 = V s / ( 1 – D )

View Answer

B. V 0 = D V s

 

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