During normal operation, a current transformer (CT) transforms higher
current into a more manageable secondary current. This transformation
is made possible by copper coils wrapped around an iron core, with the
ratio between primary and secondary currents determined by the ratio
between the number of primary and secondary turns. Bar- and windowtype CTs do not have a physical primary winding and are considered to
have one primary turn. When current flows through the primary winding,
the following actions occur