Multiply your appliance's voltage rating by the amperage that it draws. This will give you the power rating for your voltage transformer. For example, if the voltage rating is 110V and the amperage is 2 amps, the power rating is 220 watts.
Select a voltage transformer that is rated higher than your power requirements. This will prevent your transformer from burning out.
Select a grounded three prong plug adapter. Many universal travel adapters have grounded plugs. Make sure that it accepts grounded US plugs as it is unsafe to use power tools that are not grounded.
Plug your device into the converter, plug the converter into the plug adapter, and plug the adapter into the power outlet. Use your power tool as you normally would in the US.
Unplug the converter from the power outlet when you are finished using the tool to avoid burning out the converter.
