Transformer is one of the imported electrical appliances in the power system. It is similar to a power transformer and is also used for voltage or current in transformer circuits. The purpose of the power transformer to transform voltage and current is to transfer electrical energy, and the purpose of the transformer to transform voltage and current is to measure and monitor the voltage or current in the circuit. Power transformers generally have large capacity and large changes in voltage or current. While the transformer capacity is small, the difference in voltage or current change is small. in the measurement circuit. Transformers that transform current and power ammeters and relays are called current transformers.