In a parallel inverter the turn off time tq of thyristor and values of commutati

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Question
In a parallel inverter the turn off time t_q of thyristor and values of commutating elements L and C are related as
Options
A. t_q = pLC
B. t_q = LC
C. t_q = LC
D. t_q = LC

Correct Answer

t_q =

LC

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1. In a full bridge single phase inverter feeding RLC load
Options
A. one thyristor and one diode conduct simultaneously
B. two thyristors conduct simultaneously
C. two thyristors or two diodes conduct simultaneously
D. four thyristors conduct simultaneously

3. A class E chopper
Options
A. can operate in second quadrant only
B. can operate in first or third quadrant
C. can operate in all the four quadrants
D. can operate in either second or third quadrant

4. Which statement is correct?
Options
A. BJT and MOSFET are current controlled devices
B. BJT is voltage controlled and MOSFET is current controlled device
C. BJT and MOSFET are voltage controlled devices
D. BJT is current controlled and MOSFET is voltage controlled device

5. 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
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

7. A rectifier is fed by a transformer. The rms voltage and current at secondary of transformer are V_s and I_s. Output dc power is V_dc I_dc and output ac power is (V_rms ) (I_rms), Transformer utilisation factor TUF is
Options
A.
B.
C.
D.

8. In the below figure, the load is highly inductive. The firing angle is a for each of the thyristors. The periods of conduction of Th₁ and Th₂ respectively are
Options
A. 0 to p and p to 2p
B. a to p and p + a to 2p
C. a to p + a and p + p to 2p + a
D. a to p - a and p + a to 2p - a

9. A single phase semiconverter is feeding a highly inductive load and has a freewheeling diode across the load. The waveshape of input current is
Options
A. sinusoidal
B. rectangular
C. sinusoidal or rectangular
D. triangular

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