What is the effect of a CT on electrical current?

A current transformer (CT) is designed to provide a scaled-down version of the electrical current flowing through a conductor, allowing for safer measurement and monitoring. The most common standardized output of a CT is indeed 5 amps, which means that regardless of the actual current in the line, the CT will transform it to 5 amps for the purposes of measurement and protection systems. This reduction enables the use of standard equipment designed to operate with lower current levels, enhancing safety and practicality for electrical personnel.

The method by which a CT achieves this involves the principle of electromagnetic induction, where changes in the primary current create a magnetic field that induces a proportional current in the secondary winding of the transformer. Thus, this scaling down to a standardized value provides both accurate monitoring and protection without exposing operators to the high voltage present in the primary circuit.