In communication circuits, devices that increase or decrease voltage are called transformers. Transformers can convert any value of voltage into the voltage value we need with the same frequency to meet the requirements of energy transmission, distribution, and use. For example, the electricity generated by a power plant has a low voltage level and must be raised in order to be transmitted to a distant power consumption area. The power consumption area must then be reduced in voltage to a suitable voltage level for use by power equipment and daily electrical equipment.