Home / Transformer sizes from 3 to 5000 kVA
Transformer sizes from 3 to 5000 kVA
Every rating people ask about, including the ones that are not pad mounted transformers at all. Knowing which is which stops a specification going out wrong.
Pad mounted ratings we supply
| Rating | Phase | Secondary current | Cabinet, in | Weight, lb |
|---|---|---|---|---|
| 25 kVA | Single | 104 A at 240 V | 30 x 32 x 38 | 470 |
| 50 kVA | Single | 208 A at 240 V | 32 x 34 x 40 | 610 |
| 75 kVA | Single | 313 A at 240 V | 34 x 36 x 42 | 780 |
| 100 kVA | Single | 417 A at 240 V | 36 x 38 x 44 | 950 |
| 167 kVA | Single | 696 A at 240 V | 40 x 42 x 48 | 1,240 |
| 45 kVA | Three | 54.1 A at 480Y/277 | 48 x 46 x 52 | 1,350 |
| 75 kVA | Three | 90.2 A at 480Y/277 | 52 x 50 x 55 | 1,750 |
| 112.5 kVA | Three | 135 A at 480Y/277 | 55 x 52 x 57 | 2,050 |
| 150 kVA | Three | 180 A at 480Y/277 | 58 x 54 x 60 | 2,400 |
| 225 kVA | Three | 271 A at 480Y/277 | 62 x 58 x 63 | 3,000 |
| 300 kVA | Three | 361 A at 480Y/277 | 66 x 60 x 66 | 3,500 |
| 500 kVA | Three | 601 A at 480Y/277 | 72 x 66 x 72 | 4,900 |
| 750 kVA | Three | 902 A at 480Y/277 | 80 x 72 x 78 | 6,600 |
| 1000 kVA | Three | 1,203 A at 480Y/277 | 86 x 76 x 82 | 8,200 |
| 1500 kVA | Three | 1,804 A at 480Y/277 | 96 x 84 x 90 | 11,500 |
| 2000 kVA | Three | 2,406 A at 480Y/277 | 104 x 90 x 96 | 14,500 |
| 2500 kVA | Three | 3,007 A at 480Y/277 | 112 x 96 x 102 | 17,500 |
Other ratings people ask about
These are dry type units, control transformers or IEC ratings rather than US standard pad mounted sizes. Each page gives the full load current and the nearest pad mounted rating.
| Rating | What it is | Pad mounted |
|---|---|---|
| 3 kVA | Control | No |
| 5 kVA | Control or small dry type | No |
| 10 kVA | Dry type or control | No |
| 15 kVA | Dry type or control | No |
| 20 kVA | Dry type | No |
| 30 kVA | Dry type | No |
| 35 kVA | Dry type or single phase pad mount | Sometimes |
| 40 kVA | Dry type | No |
| 60 kVA | Dry type | No |
| 125 kVA | Dry type or IEC | No |
| 200 kVA | IEC or special build | No |
| 250 kVA | IEC or single phase pad mount | Sometimes |
| 630 kVA | IEC standard | No |
| 5000 kVA | Large pad mount or substation | Yes |
Free to cite with a link to this page. For any rating at any voltage, use the kVA to amps calculator.
Common questions
What is the smallest pad mounted transformer
25 kVA single phase and 45 kVA three phase. Below those the cost of the pad, the cabinet and the installation outweighs the transformer, so the job goes to a dry type unit indoors or a pole mounted unit overhead.
What is the largest pad mounted transformer
Around 5000 kVA. Above that the equipment becomes a substation transformer with separate switchgear and different clearance rules.
Why is 2550 kVA a standard size
Because DOE 2016 efficiency rules under 10 CFR Part 431 apply to three phase distribution transformers up to 2500 kVA. A 2550 kVA unit sits just above that threshold and is exempt, which makes it cheaper to build. A number of buyers order 2550 rather than 2500 for that reason alone.
Is a 630 kVA transformer available in the US
Not as a standard rating. 630 kVA is an IEC size used in Europe, Asia and the Middle East, normally at 400Y/230 volts. The nearest US standard ratings are 500 and 750 kVA.
Does a bigger transformer cost more per kVA
No, the opposite. Price per kVA falls steeply as rating rises, because the tank, cabinet, bushings, switches and freight cost roughly the same at 75 kVA as at 500. Only the core and windings scale with the rating.