What to check before ordering
Close enough to 12470 that most manufacturers build one unit covering both, with full capacity taps two above and two below nominal at 2.5 percent each. Ask for that rather than ordering a dedicated 13200 build.
Current at each rating
Three phase full load current on both sides of a 13200 GY/7620 V to 480Y/277 V transformer. The higher voltage side always carries less current for the same kVA.
| kVA | 13200 GY/7620 V side | 480Y/277 V side |
|---|---|---|
| 15 | 0.7 A | 18.0 A |
| 30 | 1.3 A | 36.1 A |
| 45 | 2.0 A | 54.1 A |
| 75 | 3.3 A | 90.2 A |
| 112.5 | 4.9 A | 135 A |
| 150 | 6.6 A | 180 A |
| 225 | 9.8 A | 271 A |
| 300 | 13.1 A | 361 A |
| 500 | 21.9 A | 601 A |
Nameplate full load current, computed from the standard three phase formula. Free to cite with a link to this page. For any rating not listed, use the kVA to amps calculator.
Common questions
What transformer do I need to go from 13200 GY/7620 V to 480Y/277 V
A step down transformer with a 27.5 to 1 ratio. The other common US primary distribution voltage, used by a large number of utilities and cooperatives instead of 12470. Most units for this conversion fall in the 45 to 2500 kVA range.
How many amps does a 13200 GY/7620 V to 480Y/277 V transformer draw
It depends on the kVA. At 100 kVA the 13200 GY/7620 V side carries about 4.4 amps and the 480Y/277 V side about 120 amps. Current is kVA times 1000 divided by the voltage times the square root of three, so the higher voltage side always carries less current for the same kVA.
What should I check before ordering
Close enough to 12470 that most manufacturers build one unit covering both, with full capacity taps two above and two below nominal at 2.5 percent each. Ask for that rather than ordering a dedicated 13200 build.