A current transformer is an instrument that measures by converting a large current on the primary side into a small current on the secondary side based on the principle of electromagnetic induction. A current transformer is composed of a closed iron core and windings. Its primary winding has very few turns and is connected in series in the circuit of the current to be measured.

Therefore, it often has the entire current of the circuit flowing through it. The secondary winding has a relatively large number of turns and is connected in series in the measuring instrument and protection circuit. When the current transformer is working, its secondary circuit is always closed, so the impedance of the series coil in the measuring instrument and protection circuit is very small, and the working state of the current transformer is close to a short circuit. A current transformer converts the large current on the primary side into a small current on the secondary side for measurement. The secondary side must not be open-circuited. The entry introduces its working principle, parameter description, classification, usage introduction, etc.