The transformer is usually rated in terms of its input and output voltages and apparent power that it is designed to safely deliver.
What are the meanings of these transformer ratings?
The voltage ratio indicates that the transformer has two windings, the high-voltage winding is rated for 1100 Volts and the low-voltage winding for 110 volts.
These voltages are proportional to their respective number of turns. Therefore, the voltage ratio also represents the turns ratio a or k.
Why Transformer Rating In kVA, Not in KW?
Answer is very simple transformer is a static device two type of losses in a transformer;1. Copper Losses
2. Iron Losses or Core Losses or Insulation Losses.
Iron Losses or Core Losses or Insulation Losses depends on Voltage while Copper losses ( I²R) are variable losses varies with Current passing through transformer windings.at the time of manufacturing its not decided that which kind of load will be added to transformer.We can't predict the power factor while designing the machine, because power factor depends upon the load which varies time to time.without including power factor we have to give rating so That’s why the Transformer Rating may be expressed in kVA, Not in kW.
