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ECE Objective Questions { Power Semiconductor Devices and Their Applications }



99. In a 3-phase semiconverter, for firing angle less than or equal to 60?, freewheeling diode conducts for
A. 30?
B. 60?
C. 90?
D.2

100. In a 3-phase semiconverter, for firing angle equal to 120? and extinction angle equal to 110? free-wheeling diode conducts for
A. 10?
B. 30?
C. 50?
D. 70?

101. In a 3-phase semiconverter, the three SCRs are triggered at intervals of
A. 60?
B. 90?
C. 120?
D. 150?

102. In a 3-phase full converter the six SCRs are fired at intervals of
A. 30?
B.600
C.900
D. 120?

103. The frequency of the ripple in the output voltage of a 3-phase scmiconverter depends upon
A. firing angle and load resistance
B. firing angle arid supply frequency
C. firing angle and load inductance
D. only on load circuit parameters

104.  In a 3-phase full converter, if the load currents island ripple - free, then the average thyristor current is
A. 1/2
B. 1/3
C. 1/4
D. 1/5

105. 1n a single-phase full converter, if the load current island ripple-free, then the average thyristor current is
A. 1/2
B. 1/3
C. 1/4
D. 1/5

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