This European Standard covers specific characteristics of traction transformers as defined in 1.3.1, used in traction substation or along the track for the supply of power to a.c. and d.c. traction systems or to provide power to auxiliary services. Traction transformers are either-single-phase traction transformers,-single-, three- or poly-phase rectifier-transformers or converter/inverter-transformers for d.c. or a.c. contact line,-single phase auto-transformers for traction power supply,-single- or three-phase auxiliary transformers at traction supply voltage.Transformers feeding a.c. contact lines are covered by EN 60076. Dry-type transformers are covered by HD 464. These standards are valid with the additional requirements given in this document.For transformers feeding contact lines through static converters EN 61378-1 may assist, but modified or additional requirements are given in this document.NOTE Transformers mounted on-board traction vehicles are covered by EN 60310 and are excluded from the scope of this document.Electromagnetic compatibility is ruled by EN 60076-1 which states that a transformer may be considered a passive element in this respect.Some accessories however are subject to EMC requirements and shall comply with EN 50121-5.