How Electronic Transformers Work

A transformer transfers electricity from one circuit to another. Electric companies generate power at very high voltages to reduce energy loss over long distances. A transformer at the point of consumption reduces the voltage to the level needed for consumption.

Structure

The simplest possible transformer consists of two electric circuits and an electrically conductive core. The core in a simple transformer is made of iron and has a square shape with a large square hole in the middle. The wire carrying the electrical current is wrapped around one side of the core, and the wire for the second electrical circuit is wrapped around the opposite side of the core.

Function

An electrical load is placed on the second circuit, causing the electrical current in the first circuit to flow through the core and into the second circuit. This produces an electrical current in the second circuit with a phenomenon known as induction. The total amount of power between the two circuits is virtually unchanged.

Voltage

The proportion of voltage between the two circuits is equal to the proportion of windings between the two circuits. This relationship can be expressed mathematically as Vp/Vs = Np/Ns, where Vp is the voltage in the first circuit, Vs is the voltage in the second circuit, Np is the number of windings in the first circuit, and Ns is the number of windings in the second circuit. This equation applies to a perfect transformer that does not lose energy. Real transformers are very efficient, although they all lose some energy.