This standard specifies the performance parameters, technical requirements, inspection rules and methods, signs, packaging, transportation and storage of three-phase dry-type power transformers. This standard is applicable to voltage levels of 6 kV, 10 kV, 20 kV and 35 kV, rated frequency of 50 Hz, rated capacity of 30 kV ? A~25 000 kV ? Regulating three-phase dry-type power transformer. Products with other rated capacities can refer to this standard. This standard does not apply to gas-filled transformers.