What is the definition of current transformer?

A current transformer (CT) is an instrument transformer designed to provide a secondary current that is accurately proportional to the primary current flowing through its primary winding. The primary purpose of a current transformer is to reduce high currents to a lower, safer level so that the reduced currents can be easily measured and monitored by instruments such as ammeters, meters, or for protection purposes in electrical power systems.

Current transformers are essential components in electrical networks for measuring and protective relaying purposes, ensuring accurate current measurement for metering and providing isolation between the high voltage system and the low voltage measurement or protective devices. They are employed extensively in substations, where they enable the safe monitoring and control of electrical power systems.