What do Potential Transformers (PTs) do?

• A. Step down the circuit's high voltage to a desired secondary voltage
• B. Step up the circuit's high voltage to a desired level
• C. Isolate the circuit from the system
• D. Provide a neutral ground for grounding

Answer: (A)

Potential transformers are voltage transformers that scale down the high circuit voltage to a lower, safe secondary voltage for measurement and protection equipment. By delivering a secondary voltage that is proportional to the primary, meters and relays can accurately monitor system voltage without being exposed to the high line voltage. This step-down action is the core function, and while PTs do provide galvanic isolation between primary and secondary as a safety feature, the primary purpose in applications like metering and protection is to convert the high voltage to a usable, lower level. They do not step the voltage up, and they aren’t used to provide grounding, so those options don’t fit.