IEEE C57.110-1998

The recommended practice applies only to two winding transformers covered by ANSI/IEEE C57.12.00, ANSI/IEEE C57.12.01 and NEMA St. 20. It does not apply to Rectifier Transformers. The purpose of this document is to establish uniform methods for determining the capability of transformers to supply nonsinusoidal load currents of known characteristics. Revision Standard - Superseded. Superseded by IEEE Std C57.110-2008. Methods are developed to conservatively evaluate the feasibility of supplying additional nonsinusoidal load currents from an existing installed dry-type or liquified transformer, as a portion of the total load. Clarification of the necessary application information is provided to assist in properly specifying a new transformer expected to carry a load, a portion of which is composed of nonsinusoidal load currents. A number of examples illustrating these methods and calculations are presented. Reference annexes make a comparison of the document calculations to calculations found in other industry standards and suggested temperature rise methods are detailed for reference purposes.