Applies to power transformers complying with IEC 76. Object is to assist purchasers in the determination and selection of transformer characteristics at the time of purchase and subsequent usage. Comprises clauses on specification of tapping quantities, selection of winding connections for transformers for three-phase systems, parallel operation of transformers in three-phase systems (appendix gives examples, based on maximum current and maximum voltage of each winding), loading capability of the neutral point of windings in star or zigzag connection, and calculation of voltage drop (or rise) for a specified load condition.