Current Transformer (CT)

A device used to transform electrical current from one level to another with a specific ratio. For example, a 5000:5 current transformer transforms current on the primary side to current on the secondary side with a ratio of 1000:1. CTs are typically used to transform large currents to much smaller currents so that standard metering equipment can be used on a variety of circuits by measuring the secondary current rather than the large primary current.