What Is A Current Transformer And Why Is It Used?

A current transformer is a "meter" transformer that reduces a high value of current to a lower value.

As their name suggests, instrument transformers are used to isolate instrumentation equipment from high voltages and currents to facilitate the measurement of electricity.

Current transformers are widely used to measure current and monitor grid operation. There are two reasons for the need for current transformers:

It isolates the protection system from high voltages and currents, thereby reducing the size and cost of protection equipment.

The output of the current transformer is standard (i.e. 1A or 5A) without the need for protection devices such as relays with different operating values.

The structure of the current transformer:

The structure of a current transformer is very similar to that of a normal transformer. The iron core of the current transformer is composed of silicon steel laminations.

A current transformer (CT) basically has one or more turns of a primary coil of a large cross-sectional area. In some cases, the strip carrying the high current may act as the primary. It is in series with the line carrying the high current.

Working principle:

The structure of the current transformer is not only similar to the ordinary transformer but also the working principle is the same.

The alternating current in the primary winding induces a magnetic flux in the iron core, which is transferred to the secondary winding where the alternating current is induced.

These transformers are basically step-up transformers, i.e. step up the voltage from the primary to the secondary. Therefore, the current decreases from primary to secondary.