scope:

This standard defines the terminal markings and connections for distribution, power, and regulating transformers covered in the IEEE C57 series of standards, guides, and recommended practices.

Purpose

The standard provides a consistent method for terminal markings and connections for single-phase and three-phase distribution, power, and regulating transformers. It designates terminal markings for interchangeability showing the sequence, external terminations, neutral terminations, grounded terminations, and marking of full and tap winding terminations. It also puts forth the connections of singlephase transformers in various configurations and describes the angular displacement of three-phase transformers when connected to various system phase displacements.