Transformers are devices that utilize the principle of electromagnetic induction to alter AC voltage, consisting primarily of primary windings, secondary windings, and an iron core (magnetic core). Their main functions include voltage transformation, current transformation, impedance transformation, isolation, and voltage stabilization (magnetic saturation transformers).

Transformers can be categorized by their applications into: distribution transformers, power transformers, fully sealed transformers, modular transformers, dry-type transformers, oil-immersed transformers, single-phase transformers, furnace transformers, rectifier transformers, reactors, anti-interference transformers, lightning protection transformers, box-type transformer test transformers, corner transformers, high-current transformers, excitation transformers, and more.

Transformers are fundamental equipment for power transmission and distribution, widely used in industries, agriculture, transportation, and urban communities. China has approximately 17 million transformers in operation, with a total capacity of about 11 billion kilovolts-amps. Transformer losses account for about 40% of the power transmission and distribution losses, presenting significant potential for energy saving.