KVA- kilo volt ampere or MVA- mega volt ampere is the main rating information of a transformer. This can be calculated from primary or secondary winding voltage and current information.
KVA is calculated by multiplying the line to line maximum voltage & maximum phase current; then multiplying this value with 1.732 in case of three phase ; lastly dividing the final value by 1000 for KVA and 100,000 for MVA
Why electrical equipments rated in KVA not in KW
Mathematical calculation for KVA and MVA for transformer
This calculation applicable for both the primary and secondary winding of a transformer.
V= line to line voltage (maximum), I= phase current (maximum)
For three phase KVA= (V*I*1.732)/1000
For single phase KVA= (V*I)/1000
For three phase MVA= (V*I*1.732)/100,000
For single phase MVA= (V*I)/1000,000