Current Transformers

A current transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary. Current transformers, along with voltage or potential transformers, are instrument transformers. Instrument transformers scale the large values of voltage or current to small, standardized values that are easy to handle for measuring instruments and protective relays. A current transformer is designed to maintain an accurate ratio between the currents in its primary and secondary circuits over a defined range. Current transformers are used extensively for measuring current and monitoring the operation of the power grid. Current transformers are often used to monitor high currents or currents at high voltages. Technical standards and design practices are used to ensure the safety of installations using current transformers.