The transformer is specified with an apparent power rating (kVA or VA ) instead of kW. The transformers are designed to be based on current and the voltage required for the transformer's operation. Therefore, the manufacturers pasted the details on the specification of it on the nameplate of the transformer in the form of VA (Volt-Amps). The specification of the Volt-Amps on the nameplate also denotes the rating of a transformer.
The rating of the transformer can also be considered the maximum current and voltage that can be safely applied to the transformer. The transformer current is used to calculate copper losses and the voltage for the iron losses.
Transformers Ratings are Expressed in Terms of?
The rating of a transformer solely depends upon the temperature rise. The temperature rise depends upon the transformer's losses. The proper cooling system maintains the transformer's temperature within permissible limits.
The transformers' rating gets higher if its cooling system is effective and vice versa. Therefore, the cooling system's effectiveness plays a significant role in the transformer's rating.