本标准规定了干式变压器的效率值。建议将总拥有成本（TOC）方法作为实现这些效率的手段，尤其是对于电力设施。本标准还基于符合能源成本条件的经修改的TOC方法，为公用事业公司以外的用户规定了最佳方法。本标准涵盖单相和三相独立装置或较大组件的部件，标称频率为60 Hz，高压绕组为35 kV或以下，单相额定电压为15至833 kVA，三相额定电压为15至7500 kVA。本标准描述了影响效率的特殊特性，并对表1中规定的效率值进行了必要的修改。

This Standard specifies efficiency values for dry-type transformers. The total ownership cost (TOC) methodology is recommended as the means for achieving these efficiencies, particularly for electric utilities. This Standard also specifies an optimal method for users other than utilities, based on a modified TOC methodology that meets the conditions of energy cost.This Standard covers single-phase and three-phase self-contained units or components of larger assemblies, nominal frequency of 60 Hz, having a high-voltage winding of 35 kV or less, ANN, rated 15 to 833 kVA for single-phase and 15 to 7500 kVA for three-phase.This Standard describes the special features that influence efficiency and provides modifications to the efficiency values specified in Table 1 where such modifications are necessary.