Transformer kVA size

Every stage is shown so the assumption driving the pick stays visible. What this does not do: no derating for ambient temperature, altitude, harmonics, or cyclic loading; no fault level, inrush, or protection grading. Run those checks separately before committing to a frame. Insulation life is also thermally sensitive: as a rule of thumb it halves for every 6 to 8 K of extra winding hot-spot temperature, which is what the target loading number is really buying.