Potential transformers are crucial for:

Potential transformers play a vital role in electrical systems, particularly in the context of voltage measurement. Their primary function is to step down high AC voltage to a lower voltage level that is safe for measuring and monitoring purposes. This occurs while maintaining the same phase relationship between voltage and current, allowing for accurate readings when connected to metering devices or protective relays.

By providing scaled down versions of high voltages, potential transformers enable operators and protective equipment to function effectively without the risk associated with high voltage exposure. This makes them indispensable in ensuring safety and accuracy in the operation and monitoring of electrical power systems.

In contrast to the other options, potential transformers are not designed to increase current flow, calibrate frequency, or measure insulation resistance. These tasks are outside the scope of what potential transformers are intended to do, reinforcing the importance of understanding their specific application in power systems.