The Carlisle Mosquito Online

Friday, August 1, 2008


How do transformers work?


A radiator transformer
A fin transformer.
An oil-cooled transformer.

Up at the top of utility poles are large containers called transformers. We may notice a transformer only when the power goes out and someone says, “The transformer blew,” from a power surge or, worse, lightning hit. The garbage can-style transformers and their newer, sleeker cousins are on every street and are spaced approximately every two to five houses. All transformers have lightning or surge arresters, which are protective devices in the event of a surge in power from lightning or other event.

Magnetic fields and electrons

Simply put, voltage is measured by the difference of electrons flowing through the wire. The transformer contains many coils, wrapped around an iron core. As current flows it maintains a

magnetic field in the iron core. The magnetic field induces a current in a secondary core, whose voltage is proportional to the number of windings in the coil. The secondary core has fewer windings, so the voltage is reduced. This is a “stepped down” voltage, which is carried out of the transformer to the home or business as 220-240 volts. Typically computers, telephones, and toasters use 110-120 volts. There are specially used outlets for appliances such as refrigerators and stoves that need 220-240 volts.

Seeking energy savings

Transformers create heat in the process of stepping down voltage, and need to be cooled. The older “garbage can” models are filled with oil and use current to cool them. Two newer models found in Carlisle are the “radiator” and “fin” transformers, which partially use air for cooling, cutting down on energy consumption. ∆

© 2008 The Carlisle Mosquito