Correct AnswerB. Electric heating
Quick Explanation
AC voltage controllers vary the rms AC voltage supplied to a load without changing the supply frequency. A classic application is resistive electric heating, where delivered power is smoothly controlled by phase-angle or integral-cycle control.
Detailed Explanation
Concept & Reasoning
An AC voltage controller uses bidirectional semiconductor switches such as anti-parallel SCRs or a triac. By controlling the conduction interval, it changes the load rms voltage and therefore load power. Heating and lighting control are common applications; power generation/transmission are not the normal role of such controllers.
How to Solve It in the Exam
Variable AC rms voltage at same frequency → heating/lighting control.
Important Exam PointFor induction-motor applications, distinguish voltage control from variable-frequency drives.
Related Revision Path
This question sits in the revision path Power Electronics → AC Voltage Controllers → Applications .
