A single phase semiconverter is feeding a highly inductive load and has freewhee

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Question
A single phase semiconverter is feeding a highly inductive load and has freewheeling diode across the load. The waveshapes of output voltage and output current
Options
A. are similar
B. are not similar
C. may be similar or dissimilar
D. are similar only if firing angle is zero

Correct Answer

are not similar

Explanation

When freewheeling diode conducts output current exists but output voltage is zero.

Power Electronics problems

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1. The phenomenon of overlap in converter operation due to
Options
A. source resistance
B. source inductance
C. both source resistance and source inductance
D. high value of firing angle

2. 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.
Options
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

3. Current derating may be necessary when thyristors are operating in
Options
A. series
B. parallel
C. series or parallel
D. none of the above

5. If V_dc1 is the dc output voltage in half wave controlled rectifier circuit feeding resistive load and V_dc2 is the dc output voltage in full wave controlled rectifier circuit (M - 2 connection) feeding resistive load, then
Options
A. V_dc1 = 0.5 V_dc2 for all values of firing angle
B. V_dc1 = V_dc2 for all values of firing angle
C. V_dc1 ? 0.5 V_dc2 for all values of firing angle
D. V_dc1 ? 0.5 V_dc2 for all values of firing angle

6. A semiconverter feeding an RLE load operates in
Options
A. first quadrant only
B. first and second quadrants
C. first and fourth quadrants
D. first and third quadrants

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

9. The terminals of a power BJT are called
Options
A. emitter, base, collector
B. emitter, base, drain
C. source, base, drain
D. source, base, collector

10. In a single phase full wave converter (M - 2 connection) feeding a highly inductive load, the firing angle for each thyristor is a in the respective half cycle. The period of conduction of each thyristor is
Options
A. p - a
B. p
C. p + a
D. p - 2a

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