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.Management Sciences
Category: Power Electronics
In a 3 phase half wave rectifier, when firing angle is less than 90 degree, then the average dc output voltage becomes__________________?
A. Positive
B. Negative
C. Zero
D. None of these
AC power in a load can be controlled by using____________?
A. Two SCR’s in parallel opposition
B. Two SCR’s in series
C. Three SCR’s in series
D. Four SCR’s in series
For similar carrier and modulating signals, the line current used in CSI is__________?
A. Identical to line voltage in a VSI
B. Identical to line current in VSI
C. Identical to phase voltage in VSI
D. Identical to phase voltage in CSI
For power output higher than 15 kW, the suitable rectifier is________________?
A. Single phase
B. 3 phase
C. Poly phase
D. Only (b) and (c)
Under over voltage condition impedance offered by the voltage clamping device is__________?
A. low
B. High
C. moderate
D. infinity
Dynamic equalising circuit is useful____________?
A. To limit di / dt of SCR
B. To limit dV / dt of SCR
C. For voltage equalisation
D. Both B and C
Thyristor can be protected from over voltages by using____________?
A. voltage clamping device.
B. fuse.
C. heat sink.
D. snubber circuit.
Between the incoming and outgoing devices in voltage commutation
A. Large overlapping takes place
B. Small overlapping operation
C. No overlapping operation
D. None of these
The ac output voltage waveform of VSI and AC output current waveform of CSI respectively is composed of___________?
A. High dv / dt, low di / dt
B. Low dv / dt, low di / dt
C. Low dv / dt, high di / dt
D. High dv / dt, high di / dt
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