Transformers are passive electrical devices used for transferring energy between two or more circuits. They are mainly designed with differing current on one coil to induce varying electromagnetic force in a second coil on the same core. They operate on the basis of Faraday's law of induction which describes the induced voltage impact in a coil when the magnetic flux is encircled by a coil.
Transformers are made to either increase or decrease voltages in industrial, commercial, or residential power applications. The change of voltage in a transformer is dependent on the turn ratios between the primary and secondary coils. Transformers are also used in individual electrical appliances to control the power input for running them.
Some transformers, especially the high voltage models, have taps
on the windings to help correct for high or low voltage conditions without affecting the full rated output voltages at the secondary terminals.
Transformers can fall into two main categories. Isolating transformers are the models that have a partition between the primary and secondary windings. The second model is the shielded design that uses a metallic shield between the primary and secondary windings to help attenuate noise.