What is the function of the CT and PT in a power system?

The function of current transformers (CT) and potential transformers (PT) in a power system is essential for the safe and accurate monitoring and measurement of electrical parameters.

Current transformers are primarily used to step down high current levels to a lower, manageable value that can be safely handled by measurement and protective relays. This allows for accurate measurement of electrical current flowing through a power system while also ensuring the safety of operators and equipment.

Potential transformers serve a similar function for voltage. They step down high voltage levels to a lower voltage that is suitable for use by metering equipment and relays. This enables accurate voltage measurement and helps in the protection and control of power system components.

Both CTs and PTs effectively allow for the safe interfacing of high voltage and high current parts of the power system with low voltage control and measurement equipment, maintaining operational integrity and safety across the system. Hence, the correct answer reflects the specific role of these transformers in adapting the high voltage power source for use with low voltage relays and measurement equipment.