Q.1
Between the peak point and the valley point of UJT emitter characteristics we have ___________ region
Q.2
After peak point, the UJT operates in the ___________ region.
Q.3
The device that exhibits negative resistance region is ___________.
Q.4
When the emitter terminal of a UJT is open, the resistance between the base terminal is generally ___________.
Q.5
A UJT is sometimes called ___________ diode.
  • Low resistance
  • High resistance
  • Single-base
  • Double-base
Q.6
The four quadrant operation of dual converters can be obtained by
  • moving the mechanical lever
  • changing the firing angle value
  • adding inductance to the circuit
  • none of the mentioned
Q.7
A single phase full bridge inverter can operate in load commutation mode if load consists of
  • RLC overdamped
  • RLC critically damped
  • RLC underdamped
  • RLC undamped
Q.8
A single full converter alone can given a
  • two quadrant operation
  • three quadrant operation
  • four quadrant operation,
  • none of the mentioned
Q.9
Which device can be used in a chopper circuit?
  • GTO
  • ALL THE ABOVE
  • BJT
  • MOSFET
Q.10
Which of the following statements is correct in connection with the inverters?
  • VSI and CSI both require feedback diodes
  • only CSI require feedback diodes
  • GTO is used in current source inverter
  • only VSI requires feedback diodes
Q.11
The major advantage of using dual converters is that
  • it is cheaply available
  • no mechanical switch is required to change the mode of operation
  • it has better pf
  • its operating frequency is very high
Q.12
In AC voltage controllers the
  • variable ac with fixed frequency is obtained
  • variable ac with variable frequency is obtained
  • variable dc with fixed frequency is obtained
  • variable dc with variable frequency is obtained
Q.13
The values of duty cycle (α) lies between..........
  • 1<α<100
  • 0<=α<=1
  • 0>α>-1
  • 0<α<1
Q.14
The shape of the output voltage waveform in a single PWM is
  • quasi-square wave
  • sine wave
  • triangular wave
  • square wave
Q.15
In an inverter, if the fundamental frequency isHz, if third harmonic is eliminated, then frequencies of other components in the output voltage wave, in Hz, would be
  • 250, 350, 500, higher frequencies
  • 50, 250, 350, 500
  • 50, 250, 350, 550
  • none of these
Q.16
The TRIAC is most sensitive in the _________ quadrants
  • 1st & 3rd with positive gate current
  • 1st with positive gate current & 3rd with negative gate current
  • 3rd with positive gate current & 1rd with negative gate current
  • 1st & 3rd with negative gate current
Q.17
All the modern AC-DC converters are using GTOs instead of SCRs because
  • emperature is an issue in SCRs
  • Switching losses are high in SCRs
  • GTOs have reliable commutation
  • GTOs are cheaply available today
Q.18
In case of TRC (Time Ratio Control), _________ is varied
  • firing angle
  • load cycle
  • duty cycle
  • load angle
Q.19
A voltage source inverter is normally employed when
  • source inductance is large and load inductance is small
  • source inductance is small and load inductance is large
  • both source and load inductance are large
  • both source and load inductance are small
Q.20
In the ___________ type of chopper, two stage conversions takes place.
  • AC-DC
  • AC link
  • DC link
  • None of the mentioned
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