Transformers

Transformers are devices that transfer electrical energy from one circuit to another by magnetic coupling without requiring relative motion between its parts.

For this to happen, transformers usually comprise two or more coupled windings, and, in most cases, a core to concentrate magnetic flux. An alternating voltage applied to one winding creates a time-varying magnetic flux in the core, which induces a voltage in the other windings.

By varying the relative number of turns between primary and secondary windings operators can determine the ratio of the input and output voltages, thus transforming the voltage by stepping it up or down between circuits. The term "stepping" is commonly used in transformers language.

Practical transformers did not actually appear until the 1880's. However, in less than a decade, the transformer was instrumental in seeing alternating current systems triumph over their direct current counterparts, a position in which they have remained dominant to this day.

By transforming electrical power to a high-voltage, low-current form and back again, transformers greatly reduced energy losses and enabled the economic transmission of power over long distances.

It is because of transformers that power station can be miles away from homes and still deliver adequate power over the lines. It can be argued that before any power makes it into a home or office it has gone through many transformers along the way.

In a perfect world, transformers would have no energy losses, and would therefore be 100% efficient, but that is not the case. Despite the transformer being among the most efficient of electrical machines, energy is dissipated in the windings, core, and surrounding structures. Larger transformers are generally more efficient, and those rated for electricity distribution usually perform better than 95%. A small transformer such as a plug-in "power brick" used for low-power consumer electronics may be less than 85% efficient.

There are several reasons for this loss of energy, and persons interested in electronics should spend some time learning more about transformers and how they operate as the topic is a popular one in all fields of electricity and electronics. As research continues in this area, some remarkable strides are being made in preventing this energy loss. As time goes by, this trend of preventing energy loss in transformers should only improve results.

You can learn more about transformers online or through any good electronics text book. You may wish to also learn more about schematics as they are often used in the discussion of transformers.