In a 3-phase full wave converter, if V is the maximum value of line voltage at the input, then each SCR is subjected to a peak negative voltage of
a) V
b) 3V
c) √3V
d) V/2
Q.2.
In a 3-phase semi-converter, firing angle is less than 60°, as such each SCR and diode conduct respectively for __________ (in degrees)
a) 60, 60
b) 90, 30
c) 120, 120
d) 180, 180
Q.3.
The effect of source inductance on the performance of a 3-phase controlled converter is to
a) increase the average load voltage
b) reduce the average load voltage
c) make the load current continuous
d) remove ripples from the load current
Q.4.
Which of the following converter circuits would require a neutral point?
a) 3-phase semi-converter
b) 3-phase full converter
c) 3-phase full converter with freewheeling diode
d) 3-phase half wave converter
Q.5.
The range of firing angle for a 3-phase, 3-pulse converter feeding a resistive load is __________ (in degrees).
a) 0 to 180
b) 0 to 150
c) 30 to 150
d) 30 to 180
Q.6.
A 3-phase bridge converter is given a three-phase supply in the phase sequence R-Y-B. Let the neutral to R phase voltage be Vm sinωt. The first SCR (connected to R phase) is fired at an angle of 15°. What is the maximum value at the output terminals at this instant?
a) Vm/√2
b) Vm
c) 1.5 Vm
d) 3 Vm
Q.7.
The PIV experienced by each SCRs in M-3 converter is __________ times that in a 3-phase full converter having the same output voltage.
a) 0.5
b) 1
c) 2
d) 1.5
Q.8.
Each SCR of a 3-phase 6-pulse converter conducts for
a) 120 degrees
b) 60 degrees
c) 180 degrees
d) 360 degrees
Q.9.
A 3-phase full converter has an average output voltage ofV for zero degree firing and resistive load. For a firing angle ofdegree, the output voltage would be
a) 125 V
b) 569 V
c) 365 V
d) zero
Q.10.
Semi-converters are
a) single quadrant converters
b) double quadrant converters
c) three quadrant converters
d) none of the mentioned
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