Transformers

Abstract

A knowledge of transformers is vital to both power and electronics engineers. Broadly speaking, transformers can be classified into either multi-winding transformers and auto-transformers; the most popular type of multi-winding transformer is the two-winding transformer, which is the subject of the majority of this chapter. The auto-transformer is a single-winding transformer, and is described in section 12.10. Transformers can be used either to ‘step up’ a voltage (or ‘step down’ a current), or to ‘step down’ a voltage (or‘step up’ a current). The supply voltage is connected to the primary winding of the transformer, and power is extracted from the secondary winding. The two windings have a common magnetic circuit which, in the case of a power transformer, is an iron circuit. In some electronic circuits, the transformer is used for impedance matching, which enables maximum power to be extracted from the secondary winding.