# Electronics and Communication Engineering - Power Electronics

### Exercise :: Power Electronics - Section 8

1.

In a 3 phase bridge inverter, the gating signals for the three phases have a phase difference of

 A. 120° B. 60° C. 240° D. any of the above

Explanation:

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2.

Assertion (A): The circuit of figure thyristor will conduct for 180° during positive half cycle if it is continuously fired. Reason (R): A thyristor can conduct only when it is forward biased.

 A. Both A and R are correct and R is correct explanation of A B. Both A and R correct but R is not correct explanation of A C. A is correct but R is wrong D. A is wrong but R is correct

Explanation:

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3.

The total number of leads in SCR, DIAC and TRIAC respectively are

 A. 3, 2, 3 B. 2, 3, 3 C. 3, 3, 2 D. 3, 2, 4

Explanation:

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4.

A single phase semiconverter is feeding a highly inductive load and has a freewheeling diode across the load. The waveshape of input current is

 A. sinusoidal B. rectangular C. sinusoidal or rectangular D. triangular

Explanation:

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5.

In the below figure, the load is highly inductive. The firing angle is a for each of the thyristors. The periods of conduction of Th1 and Th2 respectively are A. 0 to p and p to 2p B. a to p and p + a to 2p C. a to p + a and p + p to 2p + a D. a to p - a and p + a to 2p - a