IMG_3306 square current transformer  

A current transformer (CT) is an electrical device that is used to measure the current in a circuit. It is a type of transformer that is designed to produce a current in its secondary winding that is proportional to the current flowing in its primary winding. The primary winding of a CT is connected in series with the circuit being measured, while the secondary winding is connected to a measuring device, such as an ammeter or a wattmeter. CTs are commonly used in power systems to measure high currents, such as those flowing through transmission lines or in large motors. CTs are designed to be safe and accurate, and they are typically used in conjunction with other protective devices, such as relays, to ensure that the power system operates safely and reliably.