What Do kVA and kV Ratings Mean on a Transformer?
Quick answer — kVA/MVA is the apparent-power rating the transformer can deliver continuously at the specified temperature rise; kV is the system voltage class (e.g. 11 kV, 400 kV). Together the voltage ratio (e.g. 11/0.4 kV) and the kVA rating define the transformer — the capacity is apparent power, not real power, because a transformer also supplies reactive power.
What do kVA, kV and MVA ratings on a transformer mean?
kVA / MVA
The apparent power rating. It is the product of voltage and current; a transformer is rated in kVA/MVA (not kW) because it delivers both real and reactive power. Exceeding the kVA rating overheats the unit.
kV and voltage ratio
kV gives the voltage class of each winding; the ratio (e.g. 132/11 kV) is the no-load turns ratio. The insulation class and the bushing/connection ratings follow the kV.
Putting it together
A transformer is identified by its MVA and its voltage ratio (e.g. 25 MVA, 132/11 kV). The impedance (%Z) and no-load/load losses complete the specification.
References & standards
- IEC 60076-1
- IEEE C57.12.00
Related
Related manufacturers
Prolec GE (GE Vernova) · Prolec GE Waukesha · Hitachi Energy USA · Siemens Energy · Eaton · Virginia Transformer Corp
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Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.
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