Q.1
Dual converters provide
  • two quadrant operation
  • three quadrant operation
  • four quadrant operation
  • none of the mentioned
Q.2
In voltage source inverters
  • load voltage Vo depends on load impedance but load current Io does not depend on load impedance Z
  • both Vo and Io depends on Z
  • Io depends on Z but Vo does not depend
  • none of these
Q.3
In the three-phase bridge inverter, each step consists of
  • 30°
  • 60°
  • 90°
  • will depend on firing angle
Q.4
The load voltage of a chopper can be controlled by varying the..................
  • duty cycle
  • firing angle
  • reactor position
  • extinction angle
Q.5
What are rheostats used for?
  • Control large amounts of heat
  • Vary large amounts of current
  • Control of a circuit's power rating
  • Vary a circuit's tolerance
Q.6
A single-phase semi-converter is having continuous conduction, as such each thyristor will conduct for an angle of
  • α
  • π
  • α+π
  • π-α
Q.7
In the continuous conduction mode if the firing angle of the converter is increased beyond _________ degrees the converter operates in the _______ mode.
  • 90, rectifier
  • 180, inverter
  • 90, inverter
  • 180, rectifier
Q.8
When a UJT is turned ON, the resistance between emitter terminal and lower base terminal ___________
  • Remains the same
  • Is decreased
  • Is increased
  • None of the above
Q.9
The series-inverter control method is a/an..........
  • external frequency control method
  • external voltage control method
  • internal voltage control method
  • none of the mentioned
Q.10
What is the duty cycle of a chopper ?
  • Ton/Toff
  • Ton/T
  • T/Ton
  • Toff x Ton
Q.11
In a half wave bridge inverter circuit, the power delivered to the load by each source is given by
  • 2(Vs x Is)
  • Vs x Is
  • (Vs x Is)/2
  • None of the mentioned
Q.12
For a single phase thyristor circuit with R load & firing angle α, the conduction angle can be given by
  • π+α
  • 2π+α
  • π-α
  • α
Q.13
In a UJT, the p-type emitter is ___________ doped
  • Lightly
  • Heavily
  • Moderately
  • None of the above
Q.14
What is the purpose of a resistor?
  • control current flow
  • allow current flow
  • prevent current flow
  • allow heat to build up
Q.15
Cycloconverter converts
  • ac voltage to dc voltage
  • dc voltage to dc voltage
  • ac voltage to ac voltage at same frequency
  • ac voltage at supply frequency to ac voltage at load frequency
Q.16
A PWM switching scheme is used with a three phase inverter to
  • reduce THD with modest filtering
  • minimize the load on DC side
  • increase the life of the batteries
  • reduce low order harmonics and increase high order harmonics
Q.17
A UJT has ___________.
  • Two pn junctions
  • One pn junction
  • Three pn junctions
  • None of the above
Q.18
When the emitter terminal of a UJT is open, the resistance between the base terminal is generally ___________.
  • High
  • Low
  • Extremely low
  • None of the above
Q.19
In case of circulating current type dual converters, the reactor is inserted between
  • no reactor is used in case of circulating type dual converter
  • across the load
  • supply and converter
  • between the converters
Q.20
The ____________ region in a power diode increases its reverse voltage blocking capacity.
  • pn junction
  • drift
  • potential barrier
  • depletion layer
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