Question 58Electricity & Electronics - 1st Asst/Chief

The correct answer is C) rectifiers and thyristors. In a modern AC propulsion drive system, the conversion of constant frequency power into adjustable frequency power is commonly achieved through the use of rectifiers and thyristors. Rectifiers convert the AC input power into DC power, while thyristors (also known as controlled rectifiers) then convert the DC power back into an adjustable frequency AC output. This electronic system allows for precise control of the frequency and voltage supplied to the propulsion motor, enabling efficient and variable-speed operation. The other answer choices are incorrect because they do not accurately describe the components used in this type of power conversion system. Transformers and resistors (A) are not involved in the frequency conversion process, potentiometers and diodes (B) are not the primary components used, and rheostats and resistors (D) are not the correct combination for this application.