What is the purpose of a potential transformer (PT)?

A potential transformer (PT) serves the primary function of reducing high voltage levels to a lower, more manageable level that is suitable for metering and control devices. This enables accurate measurement of voltage without exposing sensitive measurement equipment to the high voltages present in the power system. By stepping down the voltage, the PT ensures that instruments can safely operate and provide reliable readings, which is critical for monitoring and managing electrical systems.

Using a PT allows operators to gather essential data about the system's performance while maintaining safety. The lower voltage output from the PT can be effectively used with standard metering equipment, ensuring that the readings reflect the actual high voltage levels in the system without the risk of damage or hazards associated with high voltage measurement.

In contrast, options such as increasing voltage for transmission or measuring current flow do not align with the primary function of a potential transformer, as those tasks are handled by different types of electrical devices. Additionally, acting as a circuit breaker is not a role of a PT, since circuit breakers are designed to interrupt the flow of electricity in the event of overloads or faults, rather than for voltage transformation or measurement.