Before ordering a step up transformer, first we need to determine the rating of your equipment. This will normally be marked on the back of the unit, near the power cord, or in the instruction manual. It will be given as Amps (A) or Watts (W).
Now, just multiply the Amps by the voltage, ie. 240V x 5A = 1200VA (This is the most reliable method)
However, sometimes only the Watts are given, in this case we divide Watts by 0.85, ie. 800W / 0.85 = 941VA
Now we have the equipment rating in VA, select a transformer slightly larger. ie. if your equipment is 1200VA, then you will need the 1650VA transformer.
Three phase transformers are calculated differently, please see our three phase transformers page.