Which of the following is one way to control voltage at a substation?

Controlling voltage at a substation is crucial for maintaining system stability and ensuring that electrical equipment operates efficiently. The potential transformer plays a vital role in this context. It is designed to scale down high voltages to a level that is safe and manageable for measurement and control purposes. This allows for accurate monitoring of voltage levels, which is essential for the operation of protective relays and other control devices within the substation.

While other components like voltage regulators, fuses, and capacitor banks each play important roles in the broader context of voltage management and system reliability, they serve different functions. A voltage regulator primarily adjusts output voltage to maintain a constant level despite fluctuations in input voltage or load conditions. Fuses provide overcurrent protection by interrupting the circuit when an overload occurs, and capacitor banks help improve power factor and voltage support but do not directly measure or control voltage for monitoring purposes.

In summary, potential transformers are critical in controlling and monitoring voltage levels by providing scaled voltage readings, which are essential for the overall operation of substation equipment and the protection of the electrical grid.