Transformer (Xfmr) 

A Transformer is an electrical device that transfers energy between two or more circuits through electromagnetic induction. Transformers are used to increase or decrease the alternating voltages in electric power applications. Transformers are either step-up, step-down, or isolation types. A step-up transformer increases the voltage of an alternating current (AC) input, while a step-down transformer decreases the voltage. An isolation transformer blocks any DC component of an AC input from passing through to the output.

The primary winding of a transformer is wound around the iron core and the secondary winding is wound around the primary winding. The AC input is applied to the primary winding and the AC output is taken from the secondary winding. The transformer couples (transfers energy) between the primary and secondary windings through inductive coupling.

The number of turns in the secondary winding divided by the number of turns in the primary winding gives the transformation ratio (N): N=Ns/Np where: Ns = number of turns in secondary Np = number of turns in primary If N>1, then it is a step-up transformer If N<1, then it is a step-down transformer