Current transformer [1] is an instrument that converts the large current on the primary side into a small current on the secondary side based on the principle of electromagnetic induction for measurement. The current transformer consists of a closed iron core and windings. The number of turns in the primary side winding is very small and it is connected in the circuit where the current needs to be measured.
Therefore, the entire current of the circuit often flows through the primary side winding, and the number of turns in the secondary side winding is relatively large and it is connected in the measuring instrument and protection circuit. During operation, the secondary side circuit of the current transformer is always closed, so the impedance of the series-connected coils of the measuring instrument and the protection circuit is very small, and the working state of the current transformer is close to a short circuit. The current transformer converts the large current on the primary side into a small current on the secondary side for measurement, and the secondary side must not be open-circuited. The entry provides information on its working principle, parameter description, classification, and usage introduction, etc.