Rating represents capability. A transformer core and winding insulation are designed to be capable of sustaining and withstanding a certain maximum voltage. The winding has a conductor cross section and cooling which allow it to carry a certain maximum current. The product of these two capabilities is volts x amps = VA or kVA. The transformer is thus limited by its VA loading and not directly by its kW load.
KVA is the virtual power that can be drawn from the tranformer. This is not usually specified in watts because the type of load used - resistive or reactive - is unknown.
The rating of a transformer depends on the allowable temperature rise in it, and that depends on the losses in the transformer. The losses are dependent on the primary voltage and the current squared, not the output power, because of the power factor.
kilo volt amp.
please explain in detail
