scope:

This European Standard 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. NOTE 1 - 'Large power transformer' means a power transformer with a highest voltage for equipment exceeding 36 kV and a rated power equal to or higher than 5 kVA, or a rated power equal to or higher than 40 MVA regardless of the highest voltage for equipment. Large power transformers are in the scope of EN 50629. NOTE 2 - Transformers with tap changer (DETC or OLTC) are included in this European Standard even if they have separate tapping winding. The object of this European Standard is to set up requirements related to electrical characteristics and design of medium power transformers. The following transformers are excluded from this European Standard: a) instrument transformers, specifically designed to supply measuring instruments, meters, relays and other similar apparatus; b) transformers with low-voltage windings specifically designed for use with rectifiers to provide a DC supply; c) transformers specifically designed to be directly connected to a furnace; d) transformers specifically designed for offshore applications and floating offshore applications; e) transformers specially designed for emergency installations; f) transformers and auto-transformers specifically designed for railway feeding systems; g) earthing or grounding transformers, this is, three-phase transformers intended to provide a neutral point for system grounding purposes; h) traction t ...