Transformer rating is usually expressed in terms of kVA. This is actually not so important for the purpose of understanding the ratings, because if we take into account that a transformer performs a similar function to an electric power supply, then it makes no difference whether we express it in terms of kVA or kWh.
“The transformer ratings are usually expressed in terms of kVA”
The transformer rating is the power consumption (in watts) of a transformer. The kVA depends on the frequency, type of transformer and its size. You can find the kVAR ratings for transformers in this website. http://nepsi.com/resources/calculators/calculation-of-capacitor-kvar.htm
Transformer rating is usually expressed in terms of kVA. This is actually not so important for the purpose of understanding the ratings, because if we take into account that a transformer performs a similar function to an electric power supply, then it makes no difference whether we express it in terms of kVA or kWh.