Transformer name plate

Answer:

Transformer name plate shows the rating of the transformer...viz., operating frequency, rated current n voltage, output power in KVA, type of insulation used, tranformation turns ratio...

Additional Info: in addition to that, you would also find the percent impedance, size of the tank, tap configuration, and vector group. Here is photo of a typical power transformer nameplate: http://www.jcmiras.net/jcm2/p20.htm