In North America, most electrical wall outlets have a rating of 120 volts. However, this is not the case everywhere in the world. In Europe, for example, wall power has a rating of 240 volts. This can make things difficult if you want to import a European appliance and use it in North America, or if you want to use an American appliance in Europe. The solution for changing 120 volts of wall power to 240 volts is to use a step-up transformer. A step-up transformer, when placed between the appliance and the wall voltage, will allow you to use 120 volts of wall power to run a 240-volt appliance. Since the configuration of plugs is different in various regions, you may also find it necessary to use plug adaptors.
Plug the step-up transformer into the 120-volt wall outlet. Use a plug adaptor if necessary.
Turn on the power switch on the transformer, if there is one. A 240-volt output is now available.
Plug any appliance or electronic device into the 240-volt socket on the transformer. Use a plug adaptor if necessary.
If you want to make a 120-volt appliance work with 240-volt wall power -- for example, if you want to use an American shaver in Europe -- you will need a step-down transformer instead. The procedure for using a step-down transformer is exactly the same as using a step-up transformer; only the voltages are reversed.
Check the power rating on your transformer and your appliance. Don't exceed the number of amps the transformer is rated for with your appliance.