Question

A 3-\(\phi\) fully controlled converter can be operated as a semi-converter, if
(a) One of the input ac supplies is disconnected and the thyristors connected to it are triggered at 180 degrees.
(b) One of the input ac supplies is disconnected and the thyristors connected to it are triggered at zero degrees.
(c) A free-wheeling diode can be connected across the load in the same direction of thyristors
(d) A free-wheeling diode can be connected across the load in the opposite direction of thyristors
Choose the correct answer

• A. \( \text{(a) and (c) are false} \)
• B. \( \text{(b) and (d) are false} \)
• C. \( \text{(b) and (c) are true} \)
• D. \( \text{(d) and (a) are true} \)

Hint:

To make any fully controlled converter act like a semi-converter: 1. Add a freewheeling diode across the output load to clamp negative voltage. 2. Or program a group of thyristors to fire at \(\alpha = 0^\circ\), turning them into standard diodes. This lets you quickly identify statements (b) and (c) as true.

Answer 1

The Correct Option is C