May 12, 2008 Why do we need transformers? In most cases, machines and appliances using electricity are manufactured to operate using a specific voltage and frequency. Sounds simple, right? Well, let me throw you a curve - voltage and frequency vary from place to place. Not all countries - and sometimes not all regions within the same country - generate the same voltage and frequency in their electricity. That's where transformers come in. Transformers adjust the voltage coming into the appliance to the proper level, and pump the electricity through the appliance to keep it operating properly. The most common, and preferred, class of transformer is the autotransformer - particularly those with a single tapped winding (as opposed to isolation transformers with 2 separate windings). Autotransformers are smaller, lighter, and provide greater voltage stability and overload tolerance. While transformers do adjust voltage, they do not - and cannot - change frequency. In most cases, frequency is irrelevant to the proper operation of the appliance. Where frequency is an issue - such as with clocks, stereo components, and timers - the appliance must have both a transformer to adjust voltage, and physical adjustment of gears, pulleys, etc. to correct the speed of operation. Frequency can, however, be an issue in cases of appliances whose motors run continuously, or continuously stop and start, such as refrigerators and air conditioners. In these cases, it is a good idea to adjust your voltage up or down according to the frequency. For example, 60 Hz motors should be run at 10% less voltage when operated on 50 Hz, while 50Hz motors should be run at 10% more voltage when operated on 60Hz. Back to FAQ home page