IndiaBIX

Electronics and Communication Engineering - Power Electronics

Exercise : Power Electronics - Section 3
1.
In a dual converter both converters work as rectifiers.
True
False
Answer: Option
Explanation:

One operators as rectifier and the other as inverter.

2.
A single phase full wave regulator feeds R-L load. The best gating signal is
short duration pulses
long duration pulses
pulse train
either (a) or (b)
Answer: Option
Explanation:

To ensure proper triggering pulse train in necessary because load is R - L.

3.
A 3 phase induction motor is fed by a 3 phase ac regulator to change the stator voltage. The variation in speed will be more if
load torque is constant
load torque increases with increase in speed
load torque decreases with increase in speed
either (a) or (b)
Answer: Option
Explanation:

If load torque is constant, the change in speed is very small.

4.
A cycloconverter cannot give a frequency higher than input frequency.
True
False
Answer: Option
Explanation:

Step up cycloconverter can give a frequency higher than input frequency.

5.
A thyristor has internal power dissipation of 40W and is operated at an ambient temperature of 20°C. If thermal resistance is 1.6° C/W, the junction temperature is
114°C
164°C
94° C
84° C
Answer: Option
Explanation:

.

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