MVA is kVA with the decimal moved
One MVA is one thousand kVA. A 1 MVA transformer is a 1000 kVA transformer, and a 2.5 MVA unit is 2500 kVA. Manufacturers switch to MVA roughly where distribution equipment ends and substation equipment begins, so the unit of measurement is a rough signal of which class of machine you are looking at. Nobody calls a 300 kVA unit a 0.3 MVA unit.
Where the boundary actually sits
Pad mounted distribution transformers run up to about 5 MVA. Above that the equipment needs separate switchgear, larger clearances, different foundations and usually a fenced yard, which makes it a substation transformer rather than something you set on a pad. A 10 MVA unit is substation plant. A 100 MVA unit is transmission plant and belongs to a utility, not to a building owner.
Load capacity at these ratings
A 1 MVA transformer delivers about 1,203 amps at 480 volts, 2,406 at 240, and 139 at 4160. A 10 MVA unit at 12470 volts delivers about 463 amps. Note how the useful secondary voltage climbs with rating. Past about 2.5 MVA a 480 volt secondary needs conductors so large that the installation cost outruns the transformer, which is why large units are normally specified at 4160 volts or higher.
What to ask for at MVA scale
Impedance matters far more here, because it sets the fault current the downstream gear has to survive, and switchgear ratings are expensive. Cooling class also becomes a choice rather than a given, since ONAN may become ONAF with fans. And lead times lengthen, because fewer manufacturers build at this size and each unit is engineered rather than pulled from a standard design.
Common questions
What is MVA in a transformer
Megavolt amperes, a unit of apparent power. One MVA equals 1,000 kVA. A 1 MVA transformer and a 1000 kVA transformer are the same machine described two ways.
What does 10 MVA stand for
Ten megavolt amperes, which is 10,000 kVA. At that rating the equipment is a substation transformer rather than a pad mounted distribution unit, needing separate switchgear, larger clearances and usually a fenced enclosure.
What is the maximum load capacity of a 10 MVA transformer
10,000 kVA of apparent power. In current that is about 463 amps at 12470 volts, or about 12,028 amps at 480 volts, which is why a unit this size is almost never specified with a 480 volt secondary.
What is the largest pad mounted transformer in MVA
Around 5 MVA, which is 5000 kVA. Above that the clearances, foundations and switchgear requirements make it substation equipment rather than something that sits on a pad.
Free to cite with a link to this page. Work out current at any rating with the kVA to amps calculator.