Can the energy consumption for the cooling of the transformer when it is loaded continuously be incl. in the ‘rated power’, when the EE of the transformer is determined?

Yes. The definition of rated power in the relevant IEC/EN standard is more precise that the one in the Regulation and does not contradict it in anyway, but only qualifies it. Therefore the explanation offered in the standard is adequate to consider if the power consumption needed for cooling is to be included in the rated power when the energy efficiency of the transformer is being determined.

_{Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.}