C.T. and P.T. are used for measuring high currents and voltages.

Current Transformers (C.T.)
- Current transformers (C.T.) are used to measure high currents in power systems.
- They are designed to transform high currents down to a standardized secondary current that can be easily measured by instruments.
- C.T.s consist of a primary winding and a secondary winding.
- The primary winding is connected in series with the circuit carrying high current, while the secondary winding is connected to the measuring instrument.
- The primary winding has a large number of turns, allowing it to handle high currents without saturating the core.
- The secondary winding has a smaller number of turns, resulting in a reduced current that is proportional to the primary current.
- The turns ratio of the C.T. determines the magnitude of the secondary current for a given primary current.
- C.T.s are commonly used in power systems for protective relaying, metering, and monitoring purposes.

Potential Transformers (P.T.)
- Potential transformers (P.T.) are used to measure high voltages in power systems.
- They are designed to transform high voltages down to a standardized secondary voltage that can be easily measured by instruments.
- P.T.s consist of a primary winding and a secondary winding.
- The primary winding is connected in parallel with the circuit carrying high voltage, while the secondary winding is connected to the measuring instrument.
- The primary winding has a high number of turns, allowing it to handle high voltages without breakdown.
- The secondary winding has a smaller number of turns, resulting in a reduced voltage that is proportional to the primary voltage.
- The turns ratio of the P.T. determines the magnitude of the secondary voltage for a given primary voltage.
- P.T.s are commonly used in power systems for protective relaying, metering, and monitoring purposes.

Why C.T. and P.T. are used for measuring high currents and voltages?
- High currents and voltages in power systems can be dangerous to directly measure with instruments.
- Using C.T.s and P.T.s allows for the safe measurement of high currents and voltages by stepping down the magnitudes to levels that can be handled by instruments.
- Additionally, C.T.s and P.T.s provide electrical isolation between the high voltage/current circuits and the measuring instruments, ensuring the safety of the personnel and the equipment.
- They also help in obtaining accurate and reliable measurements by providing a standardized secondary current or voltage that can be directly used by instruments.
- C.T.s and P.T.s are essential components in power systems for various applications, including protection, monitoring, and metering.