scope:

NEN-EN 50588-1 covers medium power transformers. 'Medium power transformer' means a power transformer with a highest voltage for equipment higher than 1,1 kV, but not exceeding 36 kV and a rated power equal to or higher than 5 kVA but lower than 40 MVA. National practices may require the use of highest voltages for equipment up to (but not including) 52 kV, when the rated voltage is less than 36 kV (such as Um = 38,5 kV or Um = 40,5 kV). This is considered to be an unusual case of a large power transformer, where the requirements are those for a medium power transformer with Um = 36 kV.