How does a current transformer (CT) work?

A current transformer (CT) operates on the principle of electromagnetic induction to measure high current levels. By design, it is capable of producing a proportional lower current output that is directly related to the high current flowing through its primary winding. When an alternating current (AC) flows through the primary coil, it creates a magnetic field that induces a current in the secondary coil. This secondary current is a fraction of the primary current, scaled according to the turns ratio of the transformer.

This allows for safe measurement and monitoring of high currents, as the CT provides a lower, more manageable current output that can be used with standard measuring devices such as ammeters or protective relays without the need to directly handle high voltages or currents, thus ensuring safety and reliability in electrical systems.

The other options, while being simple electrical principles, do not accurately describe the function of a current transformer. For instance, CTs do not work by reducing high voltage or measuring voltage levels exclusively, nor do they store electrical charge like capacitors do. The primary role of a CT is solely focused on current measurement, establishing option C as the correct answer.