This European Standard applies to new three-phase and single-phase power transformers with a highest voltage for equipment exceeding 36 kV and a rated power equal or higher than 5 kVA, or a rated power equal to or higher than 40 MVA regardless of the highest voltage for equipment.The scope of this European Standard is the following:-Defining the appropriate energy efficiency criteria;-Setting of benchmark minimum efficiency levels for new transformers based on an assessment of the energy efficiency of the European transformer population installed in the last 10 years;-Proposing higher minimum efficiency levels for improving the energy efficiency of new transformers;-Providing guidance for consideration of Total Cost of Ownership.This European Standard provides also a form for efficiency data collection to inform future efficiency benchmark levels.NOTE 1This standard covers the transformers under the EU Regulation N. 548/2014 and gives additional specific indications for single phase transformers, auto transformers, multi winding transformers and for transformers with OD and OF cooling systems.Transformers considered to be out of the scope of this document are the following:-instrument transformers, specifically designed to supply measuring instruments, meters, relays and other similar apparatus,-transformers with low-voltage windings specifically designed for use with rectifiers to provide a DC supply,-transformers specifically designed to be directly connected to a furnace,-transformers specifically designed for offshore applications and floating offshore applications,-transformers specially designed for emergency installations,-transformers and auto-transformers specifically designed for railway feeding systems,-earthing or grounding transformers, this is, three-phase transformers intended to provide a neutral point for system grounding purposes,-traction transformers mounted on rolling stock, this is, transformers connected to an AC or DC contact line, directly or through a converter, used in fixed installations of railway applications,-starting transformers, specifically designed for starting three-phase induction motors so as to eliminate supply voltage dips,-testing transformers, specifically designed to be used in a circuit to produce a specific voltage or current for the purpose of testing electrical equipment,-welding transformers, specifically designed for use in arc welding equipment or resistance welding equipment,-transformers specifically designed for explosion-proof and underground mining applications,-transformers specifically designed for deep water (submerged) applications,-medium Voltage (MV) to Medium Voltage (MV) interface transformers up to 5 MVA,-large power transformers where it is demonstrated that for a particular application, technically feasible alternatives are not available to meet the minimum efficiency requirements set out by EU REGULATION N. 548/2014,-large power transformers which are like for like replacements in the same physical location/installation for existing large power transformers, where this replacement cannot be achieved without entailing disproportionate costs associated to their transportation and/or installation.For dry type large power transformers Minimum PEI values have been published in European Regulation and these values are included in Annex A.NOTE 2To retain consistency, the same list of exclusions in the EU Regulation N. 548/2014, has also been reproduced here. Within the above EU exclusion list, some had been excluded simply because no PEI data was available to CENELEC at the time on which to base appropriate PEI levels. Consequently, as such information becomes available in the future, it may be possible to derive suitable PEI Levels. Accordingly these particular categories are listed in Clause 6 as suitable for future consideration.