Power Electronics (3140915) MCQs

MCQs of Miscellaneous

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1.
A cycloconverter is a _________
(a) one stage power converter
(b) one stage voltage converter
(c) one stage frequency converter
(d) none of the mentioned
Answer:

Option (c)

2.
Applications of cycloconverters include
(a) speed control of ac drives
(b) induction heating
(c) static VAr compensation
(d) all of the mentioned
Answer:

Option (d)

3.
The single phase mid-point type cycloconverter uses __________ number of SCRs.
(a) 4
(b) 8
(c) 6
(d) none of the mentioned
Answer:

Option (a)

4.
The single phase bridge type cycloconverter uses __________ number of SCRs.
(a) 4
(b) 8
(c) 6
(d) none of the mentioned
Answer:

Option (b)

5.
The principle of three phase cycloconverter is to
(a) add and remove number of SCRs
(b) vary progressively the firing angle of the devices
(c) keep the firing angle as 0° for all the devices
(d) none of the mentioned
Answer:

Option (b)

6.
The function of snubber circuit connected across an SCR is to
(a) suppress dv/dt
(b) increase dv/dt
(c) decrease dv/dt
(d) keep transient overvoltage at a constant value.
Answer:

Option (a)

7.
The object of connecting resistance and capacitance across gate circuit is to protect the SCR gate against
(a) overvoltages
(b) dv/dt
(c) noise signals
(d) overcurrents
Answer:

Option (c)

8.
Thermal resistance in SCRs has the units of
(a) W/°C
(b) W.°C
(c) °C/W
(d) 1/°C.W
Answer:

Option (c)

9.
The heat sinks for SCRs are made from ......
(a) copper
(b) steel
(c) aluminum
(d) None of these
Answer:

Option (c)

10.
For a pulse transformer, the material used for its core and the possible turn-ratio from primary to secondary are, respectively
(a) ferrite ; 20 : 1
(b) laminated iron ; 1 : 1
(c) ferrite ; 1 : 1
(d) powdered iron; 1 : 1
Answer:

Option (c)

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