NIELIT Scientist Paper on Power Electronics

M.Sc Electronics Semester I Exam Oct/Nov 2019 Shivaji University Kolhapur

A device that converts DC power in DC power is called as _____
(a) Chopper
(b) Inverter
(c) Rectifier
(d) Cycloconverter

The class B choppers has ___ quadrant operation.
(a) one
(b) two
(c) four
(d) three

In AC voltage controller if the SCRs are switched on for 25 cycles and off for 25 cycles the duty cycle would be _____
(a) 4.0
(b) 0.20
(c) 1.0
(d) 0.50

In SPWM technique modulation index is ______
(a) 1
(b) 0 to 1
(c) 0 to 10
(d) 0

The output voltage of single phase bridge inverter is ____ wave.
(a) square
(b) sine
(c) triangular
(d) ramp

In choppers, for chopping period T, the output voltage can be controlled by varying ____Constant.
(a) T Keeping T on
(b) T on keeping T
(c) Toff keeping T
(d) Toff keeping Toff

The rectifiers can be used for _____
(a) dc motor drivers
(b) variable speed drives
(c) four quadrant operation
(d) All of these

The free-wheeling action takes place through ____ in asymmetrical configuration
(a) a SCR and a diode
(b) only a pair of diodes
(c) two SCRs and one diode
(d) a SCR and two diodes

The ______ is used to prevent short circuiting in cycloconverters.
(a) free wheeling diode
(b) intergroup reactor
(c) switch
(d) semiconductor switches

The McMurray-Bedford inverter uses ____ technique of communication.
(a) voltage communication
(b) current communication
(c) natural communication
(d) All of these

In current source inverter the input current is _____
(a) constant
(b) constant but adjustable
(c) adjustable
(d) alternating