Current Transformers

A Current Transformer is the measuring device for metering and protection system. The primary current of the CT is transformed into the required secondary current of 5 A or 1 A.

Measuring CT's have different class of accuracy I.e. 0.1, 0.2S, 0.2, 0.5S, 0.5 and 1.0 and protection CT's have 5P10, 5P20 and 10P10. In the case of special protection CT's(PS class), the Knee Point Voltage(KV) of the CT is specified along with secondary resistance and magnetizing current.

The construction of the CT not only depends upon the ratio but also on the Short Time Current Rating. Burden and Class of Accuracy.