What device is used to increase or decrease voltage?

• A. power transformer
• B. regulator
• C. capacitor bank
• D. reactor

Answer: (A)

Voltage is changed by a power transformer, which uses the turns ratio between its primary and secondary windings to step voltage up or down. When energized, the magnetic flux couples the two windings and induces a voltage on the secondary; more turns on the secondary raise the output voltage, fewer turns lower it. Power in roughly equals power out, so current adjusts inversely with the voltage change. This is the standard method for altering voltage levels in both transmission and distribution systems.

A voltage regulator mainly maintains a set voltage under varying load and conditions rather than inherently changing the system voltage level. A capacitor bank supplies or absorbs reactive power to improve voltage profiles and power factor, but doesn’t set a new voltage magnitude. A reactor provides inductive impedance to limit current or control reactive power, not to establish a different voltage level.