Measurement and calculation methods
ANNEX IISupplementary provisions
ANNEX II Measurement and calculation methods Measurement method For the purpose of compliance with the requirements of this Regulation, measurements shall be made using a reliable, accurate and reproducible measurement procedure, which takes into account the generally recognised state of the art measurement methods, including methods set out in documents the reference numbers of which have been published for that purpose in the Official Journal of the European Union . Calculation methods The methodology for calculating the Peak Efficiency Index (PEI) for medium and large power transformers is based on the ratio of the transmitted apparent power of a transformer minus the electrical losses to the transmitted apparent power of the transformer. Where: P 0 is the no load losses measure at rated voltage and rated frequency, on the rated tap P c0 is the electrical power required by the cooling system for no load operation P k is the measured load loss at rated current and rated frequency on the rated tap corrected to the reference temperature S r is the rated power of the transformer or autotransformer on which P k is based