When you speak of transforming from 208 to 480 , the question arises "what are you driving?" If it is just a motor, or are there a large number of relays involved?
The quick and dirty solution is just to use a transformer (two single phase) in "open delta" configuration to go from 240 to 480 volts. Most equipment that is rated 240 will operate on 208, perhaps with a little heating. If there is too much heating, using a "boost" transformer configuration can bring it to exact voltage. I offer some insight into that problem, in single phase, in
http://www.hudsontelcom.com/uploads/ShopElex.pdf This calculation involves a slightly higher current as well that should be allowed for. There are many other configurations for such a transformer, it really depends on what you can lay your hands on and how much time and money you are willing to invest.
If there is just a matter of a motor and starter,
and if the motor is a dual voltage device, rewiring the motor and changing out the contactor is a much "cheaper" conversion,
provided you do your own work. Basicly investing time vs money, your choice. If there is a number of voltage sensitive devices such as relays or internal (control) transformers, transforming the incomming line might well be the best option. There
are transformers that make this specific conversion, but make sure the wallet is prepared for such a purchase. Sometimes this is done with taps on such a transformer known as a dual purpose device.
There are many such vendors such as described above. Finding one locally is preferred as such a transformer will be quite heavy. Read as shipping cost as expensive as the transformer itself. Further, the transformer will be mostly copper windings around an iron core. They are never
cheap inexpensive for that reason alone. A twin coil starter(reversible) is a much better bargain,
if it will solve the problem.
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