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Electronics and Communication Engineering - Power Electronics

Exercise : Power Electronics - Section 2
36.
The rated current of a thyristor is 40 A. The holding current will be about :
20 A
1 A
100 mA
10 mA
Answer: Option
Explanation:

The holding current is much less then 1% of rated current.

37.
A cycloconverter is
ac-dc converter
dc-ac converter
dc-dc converter
ac-ac converter
Answer: Option
Explanation:

It changes ac at frequency f into ac at a frequency different from f.

38.
The number of leads in a power semiconductor diode are
2
3
4
2 or 3
Answer: Option
Explanation:

A diode has 2 leads irrespective of its rating.

39.
If ton and toff are the turn on and turn off times of a thyristor, then
ton and toff are almost equal
ton >> toff
toff >> ton
ton is about twice toff
Answer: Option
Explanation:

Turn on time is less than 3 μs while turn off time is between 10-300 μs.

40.

Assertion (A): The gate current of an SCR is always in the form of pulses.

Reason (R): The gate losses, in pulse triggering, are low.

Both A and R are correct and R is correct explanation of A
Both A and R correct but R is not correct explanation of A
A is correct but R is wrong
A is wrong but R is correct
Answer: Option
Explanation:

Gate current in the form of pulses is commonly used because gate losses are low.

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