Power transformers are static devices designed to change AC voltage levels at a constant frequency. They are used in various applications such as power distribution, voltage control, and industrial systems. There are different types of power transformers, including grid use transformers, instrument transformers for measurements, test units for experiments, and special-purpose transformers for industrial applications. Power transformers come in various designs, such as single-phase or three-phase, and can be air or oil-cooled. They may also feature double or triple windings, depending on the specific requirements. Built to comply with international standards like IEC and IEEE, these transformers are engineered for safety and reliable performance.