Cyclo converter drives are generally employed in

The correct answer is option 3.

Concept:

Cycloconverters:

• These circuits convert input power at one frequency to output power at a different frequency through a one-stage conversion.
• These are primarily used for slow speed large ac drives like rotary kiln etc.
• In the case of step-down cyclo-converter, the output frequency is limited to a fraction of input frequency, typically it is below 20 Hz in case 50 Hz supply frequency. In this case, no separate commutation circuits are needed as SCRs are line commutated devices.
• In the case of step-up cyclo-converter, forced commutation circuits are needed to turn OFF SCRs at the desired frequency. Such circuits are relatively very complex. Therefore, the majority of cyclo-converters are of the step-down type that lowers the frequency than the input frequency.