Transformer is a magnetically operated machine that can change values of voltage, current, and impedance without a change of frequency. Transformers step up voltage for transmission and step it down again for use inside a plant or commercial building. Transformers can be divided into three classifications: Autotransformer, current transformer, and isolation transformer.
Single-Phase Transformer operates on only one phase of AC power system.
Three-Phase Transformer is constructed by winding three single-phase transformers on a single core. They are used throughout industry to change values of three-phase voltage and current.