Assertion (A): An ac regulator uses natural commutation Reason (R): An ac regulator can be used for static on load tap changing of transformer.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the starting torque is 100 N-m. At 25 Hz, the starting torque

may be more or less than 100 N-m depending on motor parameters

Assertion (A): SUS is a PUT and avalanche diode connected between gate and cathode Reason (R): SBS has two SUS inbuilt together and connected in anti-parallel

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A GTO can be turned on and turned off by gate pulses Reason (R): A GTO can be turned off by negative gate pulse.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): The turn on time of SCR is about 1 to 4 ms. Reason (R): The turn off time of SCR is about 10 to 300 ms.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

In a single phase full wave ac regulator feeding R-L load, the gate pulses

cannot be rectangular with width (p - a)

should be rectangular with width (p - a)

cannot be rectangular with width (p - a)

Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V. Reason (R): When an SCR is conducting, the junction temperature is about 200 C.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A high dv/dt may cause triggering of a thyristor. Reason (R): A high dv/dt results in charging current in the thyristor.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

To protect an SCR against high di/dt we connect

a capacitance in series with SCR

a capacitance in parallel with SCR

an inductance in parallel with SCR

an inductance in series with SCR

Assertion (A): A GTO circuit is more compact than SCR circuit Reason (R): A GTO can be turned off by negative gate pulse.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A cycloconverter may be line commutated or forced commutated Reason (R): A step up cycloconverter requires forced commutation.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR Reason (R): Voltage across a capacitor can not change instantaneously.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A dual converter may be circulating current type or non circulating current type. Reason (R): In circulating current dual converter only one converter can be operated at one time.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): The gate current of an SCR is always in the form of pulses. Reason (R): The gate losses, in pulse triggering, are low.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): An inverter does not require forced commutation Reason (R): A series inverter is a forced commutation inverter.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): An ideal rectifier should have unity harmonic factor Reason (R): An ideal rectifier should have unity displacement factor.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A TRIAC is a bidirectional SCR. Reason (R): A TRIAC is a four layers 3 terminal device and can conduct in both directions.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A transistor requires a continuous base signal for conduction but a thyristor requires a gate pulse. Reason (R): Transistor find widespread application in power electronic circuits.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current. Reason (R): The duration of surge current is very small.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

The dynamic equalising circuit consists of a series combination of capacitor C and resistor RC across each thyristor. This resistance RC (along with parallel connected diode)

limits both charging and discharging currents

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): A fully controlled bridge converter can operate in first and fourth quadrant. Reason (R): A semi converter is cheaper than a full converter.

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

Assertion (A): When the anode current of an SCR starts increasing during turn on process, the anode cathode voltage drop starts decreasing. Reason (R): During turn on the reverse biased junction in SCR breaksdown.

Both A and R correct but R is not correct explanation of A

Both A and R are correct and R is correct explanation of A

Both A and R correct but R is not correct explanation of A

37 + Mcqs in General in Power Electronics Page 1 McqOptions

1.	Assertion (A): An ac regulator uses natural commutation Reason (R): An ac regulator can be used for static on load tap changing of transformer.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

2.	A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the starting torque is 100 N-m. At 25 Hz, the starting torque
A.	will be less than 100 N-m
B.	will be more than 100 N-m
C.	may be more or less than 100 N-m depending on motor parameters
D.	very small
Answer» C. may be more or less than 100 N-m depending on motor parameters

Discussion

3.	Assertion (A): SUS is a PUT and avalanche diode connected between gate and cathode Reason (R): SBS has two SUS inbuilt together and connected in anti-parallel
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

4.	Assertion (A): A GTO can be turned on and turned off by gate pulses Reason (R): A GTO can be turned off by negative gate pulse.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

5.	Assertion (A): The turn on time of SCR is about 1 to 4 ms. Reason (R): The turn off time of SCR is about 10 to 300 ms.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

6.	In a thyristor the gate lead is connected to the n layer near the p layer to which anode is connected.
A.	True
B.	False
Answer» C.

Discussion

7.	Which of the following are included in the architecture of computer? 1.Addressing mode, design of CPU 2.Instruction set, data format 3.Secondary memory, operating system Select the correct answer using the codes given below:
A.	1 and 2
B.	2 and 3
C.	1 and 3
D.	1, 2 and 3
Answer» B. 2 and 3

Discussion

8.	In a single phase full wave ac regulator feeding R-L load, the gate pulses
A.	are always of short duration
B.	may be of short duration
C.	should be rectangular with width (p - a)
D.	cannot be rectangular with width (p - a)
Answer» D. cannot be rectangular with width (p - a)

Discussion

9.	In a fully controlled bridge converter feeding a resistive load the waveshapes of output voltage and output current
A.	are always similar
B.	can never be similar
C.	may be similar or dissimilar
D.	are similar only if a = 0
Answer» B. can never be similar

Discussion

10.	Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V. Reason (R): When an SCR is conducting, the junction temperature is about 200 C.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» D. A is wrong but R is correct

Discussion

11.	Assertion (A): A high dv/dt may cause triggering of a thyristor. Reason (R): A high dv/dt results in charging current in the thyristor.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

12.	To protect an SCR against high di/dt we connect
A.	a capacitance in series with SCR
B.	a capacitance in parallel with SCR
C.	an inductance in parallel with SCR
D.	an inductance in series with SCR
Answer» E.

Discussion

13.	Assertion (A): A GTO circuit is more compact than SCR circuit Reason (R): A GTO can be turned off by negative gate pulse.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

14.	Assertion (A): A cycloconverter may be line commutated or forced commutated Reason (R): A step up cycloconverter requires forced commutation.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

15.	Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR Reason (R): Voltage across a capacitor can not change instantaneously.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

16.	A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the speed is 1440 rpm. At 25 Hz, the speed is likely to be
A.	about 1350 rpm
B.	about 720 rpm
C.	about 360 rpm
D.	either (b) or (c)
Answer» C. about 360 rpm

Discussion

17.	A single phase semiconverter is feeding a highly inductive load. The circuit has a freewheeling diode across the load and firing angle is a. During one cycle of input voltage, the total duration of conduction of freewheeling diode is
A.	a
B.	2 a
C.	4 a
D.	0.5 a
Answer» C. 4 a

Discussion

18.	A 3 phase bridge inverter is fed by 400 V battery. The load is star connected and has a resistance of 10 per phase. The peak value of load current is
A.	40 A
B.	20 A
C.	10 A
D.	5 A
Answer» C. 10 A

Discussion

19.	Assertion (A): A dual converter may be circulating current type or non circulating current type. Reason (R): In circulating current dual converter only one converter can be operated at one time.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» D. A is wrong but R is correct

Discussion

20.	Assertion (A): The gate current of an SCR is always in the form of pulses. Reason (R): The gate losses, in pulse triggering, are low.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

21.	In a 3 phase full wave regulator feeding resistance load connected in star, the possible range of firing angle a is
A.	0 a 180
B.	0 a 150
C.	0 a 120
D.	0 a 90
Answer» C. 0 a 120

Discussion

22.	In integral cycle control the period of on-off control should be more than mechanical time constant of load
A.	True
B.	False
Answer» C.

Discussion

23.	Assertion (A): An inverter does not require forced commutation Reason (R): A series inverter is a forced commutation inverter.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» E.

Discussion

24.	A single phase semiconverter has a freewheeling diode. If the firing angle is a and the load is purely resistive, the periods of conduction and freewheeling respectively are
A.	p - a and 0
B.	p - a and a
C.	p + a and 0
D.	p + a and a
Answer» B. p - a and a

Discussion

25.	A dc separately excited motor has a constant field current. The armature is fed from a single phase supply through a semi-converter. When a = 0, speed is 600 rpm. If a = 90 , the speed is likely to be
A.	about 300 rpm
B.	about 150 rpm
C.	about 75 rpm
D.	about zero
Answer» B. about 150 rpm

Discussion

26.	A single phase half wave rectifier is feeding a resistive load. When a = 0, dc output voltage is 127 V. When a = 30 , the dc output voltage will be about
A.	127 V
B.	120 V
C.	110 V
D.	100 V
Answer» C. 110 V

Discussion

27.	Assertion (A): An ideal rectifier should have unity harmonic factor Reason (R): An ideal rectifier should have unity displacement factor.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» E.

Discussion

28.	Assertion (A): A TRIAC is a bidirectional SCR. Reason (R): A TRIAC is a four layers 3 terminal device and can conduct in both directions.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

29.	Assertion (A): A transistor requires a continuous base signal for conduction but a thyristor requires a gate pulse. Reason (R): Transistor find widespread application in power electronic circuits.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» D. A is wrong but R is correct

Discussion

30.	Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current. Reason (R): The duration of surge current is very small.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

31.	Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

32.	A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When a = 0, speed is 500 rpm. If a = 45 , the speed is likely to be
A.	about 350 rpm
B.	about 250 rpm
C.	about 175 rpm
D.	about 125 rpm
Answer» E.

Discussion

33.	In a circuit using a full wave converter (M - 2 connection) the PIV of each thyristor is 400 V. For the same output voltage and fully controlled bridge converter, PIV will be
A.	400 V
B.	800 V
C.	200 V
D.	200v
Answer» D. 200v

Discussion

34.	The dynamic equalising circuit consists of a series combination of capacitor C and resistor RC across each thyristor. This resistance RC (along with parallel connected diode)
A.	limits charging current
B.	limits discharging current
C.	limits both charging and discharging currents
D.	none of the above
Answer» C. limits both charging and discharging currents

Discussion

35.	Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» D. A is wrong but R is correct

Discussion

36.	Assertion (A): A fully controlled bridge converter can operate in first and fourth quadrant. Reason (R): A semi converter is cheaper than a full converter.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» C. A is correct but R is wrong

Discussion

37.	Assertion (A): When the anode current of an SCR starts increasing during turn on process, the anode cathode voltage drop starts decreasing. Reason (R): During turn on the reverse biased junction in SCR breaksdown.
A.	Both A and R are correct and R is correct explanation of A
B.	Both A and R correct but R is not correct explanation of A
C.	A is correct but R is wrong
D.	A is wrong but R is correct
Answer» B. Both A and R correct but R is not correct explanation of A

Discussion

Explore topic-wise MCQs in Power Electronics.

Assertion (A): An ac regulator uses natural commutation Reason (R): An ac regulator can be used for static on load tap changing of transformer.

A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the starting torque is 100 N-m. At 25 Hz, the starting torque

Assertion (A): SUS is a PUT and avalanche diode connected between gate and cathode Reason (R): SBS has two SUS inbuilt together and connected in anti-parallel

Assertion (A): A GTO can be turned on and turned off by gate pulses Reason (R): A GTO can be turned off by negative gate pulse.

Assertion (A): The turn on time of SCR is about 1 to 4 ms. Reason (R): The turn off time of SCR is about 10 to 300 ms.

In a thyristor the gate lead is connected to the n layer near the p layer to which anode is connected.

Which of the following are included in the architecture of computer? 1.Addressing mode, design of CPU 2.Instruction set, data format 3.Secondary memory, operating system Select the correct answer using the codes given below:

In a single phase full wave ac regulator feeding R-L load, the gate pulses

In a fully controlled bridge converter feeding a resistive load the waveshapes of output voltage and output current

Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V. Reason (R): When an SCR is conducting, the junction temperature is about 200 C.

Assertion (A): A high dv/dt may cause triggering of a thyristor. Reason (R): A high dv/dt results in charging current in the thyristor.

To protect an SCR against high di/dt we connect

Assertion (A): A GTO circuit is more compact than SCR circuit Reason (R): A GTO can be turned off by negative gate pulse.

Assertion (A): A cycloconverter may be line commutated or forced commutated Reason (R): A step up cycloconverter requires forced commutation.

Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR Reason (R): Voltage across a capacitor can not change instantaneously.

A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the speed is 1440 rpm. At 25 Hz, the speed is likely to be

A single phase semiconverter is feeding a highly inductive load. The circuit has a freewheeling diode across the load and firing angle is a. During one cycle of input voltage, the total duration of conduction of freewheeling diode is

A 3 phase bridge inverter is fed by 400 V battery. The load is star connected and has a resistance of 10 per phase. The peak value of load current is

Assertion (A): A dual converter may be circulating current type or non circulating current type. Reason (R): In circulating current dual converter only one converter can be operated at one time.

Assertion (A): The gate current of an SCR is always in the form of pulses. Reason (R): The gate losses, in pulse triggering, are low.

In a 3 phase full wave regulator feeding resistance load connected in star, the possible range of firing angle a is

In integral cycle control the period of on-off control should be more than mechanical time constant of load

Assertion (A): An inverter does not require forced commutation Reason (R): A series inverter is a forced commutation inverter.

A single phase semiconverter has a freewheeling diode. If the firing angle is a and the load is purely resistive, the periods of conduction and freewheeling respectively are

A dc separately excited motor has a constant field current. The armature is fed from a single phase supply through a semi-converter. When a = 0, speed is 600 rpm. If a = 90 , the speed is likely to be

A single phase half wave rectifier is feeding a resistive load. When a = 0, dc output voltage is 127 V. When a = 30 , the dc output voltage will be about

Assertion (A): An ideal rectifier should have unity harmonic factor Reason (R): An ideal rectifier should have unity displacement factor.

Assertion (A): A TRIAC is a bidirectional SCR. Reason (R): A TRIAC is a four layers 3 terminal device and can conduct in both directions.

Assertion (A): A transistor requires a continuous base signal for conduction but a thyristor requires a gate pulse. Reason (R): Transistor find widespread application in power electronic circuits.

Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current. Reason (R): The duration of surge current is very small.

Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time.

A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When a = 0, speed is 500 rpm. If a = 45 , the speed is likely to be

In a circuit using a full wave converter (M - 2 connection) the PIV of each thyristor is 400 V. For the same output voltage and fully controlled bridge converter, PIV will be

The dynamic equalising circuit consists of a series combination of capacitor C and resistor RC across each thyristor. This resistance RC (along with parallel connected diode)

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

Assertion (A): A fully controlled bridge converter can operate in first and fourth quadrant. Reason (R): A semi converter is cheaper than a full converter.

Assertion (A): When the anode current of an SCR starts increasing during turn on process, the anode cathode voltage drop starts decreasing. Reason (R): During turn on the reverse biased junction in SCR breaksdown.

Assertion (A): An ac regulator uses natural commutation

Reason (R): An ac regulator can be used for static on load tap changing of transformer.

Assertion (A): SUS is a PUT and avalanche diode connected between gate and cathode

Reason (R): SBS has two SUS inbuilt together and connected in anti-parallel

Assertion (A): A GTO can be turned on and turned off by gate pulses

Reason (R): A GTO can be turned off by negative gate pulse.

Assertion (A): The turn on time of SCR is about 1 to 4 ms.

Reason (R): The turn off time of SCR is about 10 to 300 ms.

Which of the following are included in the architecture of computer?

1.Addressing mode, design of CPU

2.Instruction set, data format

3.Secondary memory, operating system

Select the correct answer using the codes given below:

Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V.

Reason (R): When an SCR is conducting, the junction temperature is about 200 C.

Assertion (A): A high dv/dt may cause triggering of a thyristor.

Reason (R): A high dv/dt results in charging current in the thyristor.

Assertion (A): A GTO circuit is more compact than SCR circuit

Reason (R): A GTO can be turned off by negative gate pulse.

Assertion (A): A cycloconverter may be line commutated or forced commutated

Reason (R): A step up cycloconverter requires forced commutation.

Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR

Reason (R): Voltage across a capacitor can not change instantaneously.

Assertion (A): A dual converter may be circulating current type or non circulating current type.

Reason (R): In circulating current dual converter only one converter can be operated at one time.

Assertion (A): The gate current of an SCR is always in the form of pulses.

Reason (R): The gate losses, in pulse triggering, are low.

Assertion (A): An inverter does not require forced commutation

Reason (R): A series inverter is a forced commutation inverter.

Assertion (A): An ideal rectifier should have unity harmonic factor

Reason (R): An ideal rectifier should have unity displacement factor.

Assertion (A): A TRIAC is a bidirectional SCR.

Reason (R): A TRIAC is a four layers 3 terminal device and can conduct in both directions.

Assertion (A): A transistor requires a continuous base signal for conduction but a thyristor requires a gate pulse.

Reason (R): Transistor find widespread application in power electronic circuits.

Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current.

Reason (R): The duration of surge current is very small.

Assertion (A): Inverters and choppers use fast switching thyristors

Reason (R): Fast switching SCR has low turn off time.

Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous

Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

Assertion (A): A fully controlled bridge converter can operate in first and fourth quadrant.

Reason (R): A semi converter is cheaper than a full converter.

Assertion (A): When the anode current of an SCR starts increasing during turn on process, the anode cathode voltage drop starts decreasing.

Reason (R): During turn on the reverse biased junction in SCR breaksdown.