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Electronics and Communication Engineering - Power Electronics

Exercise : Power Electronics - Section 2
1.
A dc circuit breaker must use
natural commutation
forced commutation
both natural and forced commutation
either natural or forced commutation
Answer: Option
Explanation:

Natural commutation is possible only in ac circuits.

2.
In a single phase full wave regulator feeding R-L load, the minimum firing angle can be zero.
True
False
Answer: Option
Explanation:

Range of control of a is 0 ≤ a ≤ p.

3.
An RC snubber circuit is used to protect a thyristor against :
false triggering
failure to turn on
switching transients
failure to commutate
Answer: Option
Explanation:

Especially high during switching.

4.
A DIAC has two terminals, anode and cathode.
True
False
Answer: Option
Explanation:

They are designated as T1 and T2 because diac can conduct in both directions.

5.
A single phase semiconverter has a freewheeling diode. If the firing angle is a and the load is purely resistive, the periods of conduction and freewheeling respectively are
p - a and 0
p - a and a
p + a and 0
p + a and a
Answer: Option
Explanation:

Freewheeling diode conducts only when load is inductive. If load is purely resistive free wheeling diode does not come into operation.

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