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Transformer voltage conversions
Which transformer you need to get from the voltage you have to the voltage the equipment wants, with the turns ratio and the kVA range each conversion normally lands in.
Step down
| Conversion | Ratio | Common range | Typical use |
|---|---|---|---|
| 480 V three phase to 208Y/120 V three phase | 2.31 to 1 | 15 to 300 kVA | The most common step down in North American commercial buildings. |
| 480 V to 120 V | 4 to 1 | 0.5 to 15 kVA | Control power. |
| 480 V to 240 V | 2 to 1 | 15 to 150 kVA | Feeding older equipment, shop tools and machinery built for 240 V from a 480 V service. |
| 12470 GY/7200 V to 480Y/277 V | 26 to 1 | 45 to 2500 kVA | The standard pad mounted distribution transformer in most of the US. |
| 13200 GY/7620 V to 480Y/277 V | 27.5 to 1 | 45 to 2500 kVA | The other common US primary distribution voltage, used by a large number of utilities and cooperatives instead of 12470. |
| 4160 V to 480Y/277 V | 8.7 to 1 | 75 to 2500 kVA | Industrial plants and older campuses that distribute internally at 4160 V, plus some municipal systems that never moved up to 12. |
| 34500 GY/19920 V to 480Y/277 V | 72 to 1 | 300 to 2500 kVA | Solar farms, wind sites, large rural services and utility substations where distribution runs at 34. |
| 480 V to 400Y/230 V | 1.2 to 1 | 15 to 500 kVA | Running imported European or Asian machinery, which is built for 400Y/230 at 50 or 60 Hz, from a North American 480 V service. |
Step up
| Conversion | Ratio | Common range | Typical use |
|---|---|---|---|
| 208Y/120 V to 480 V | 1 to 2.31 | 15 to 225 kVA | Running 480 V equipment in a building that only has a 208 V service. |
| 240 V to 480 V | 1 to 2 | 15 to 150 kVA | Supplying 480 V machinery from a 240 V supply, and in some cases reversing a standard step down unit to run backwards. |
A transformer changes voltage, not frequency. Free to cite with a link to this page.
Work out the current at any rating with the kVA to amps calculator, or ask for a quote.