scope:

This standard applies to the definition and application of function numbers and acronyms for devices and functions used in electrical substations and generating plants and in installations of power utilization and conversion apparatus.

NOTE-Historically, device function numbers have typically represented individual or component devices. These numbers and acronyms may also be used to represent individual functions within multi-function devices or software programs, and that may contain both protection- and non-protection-oriented functions.¹

Purpose

A device function number, with an appropriate prefix and appended suffix (or an acronym), is used to identify the function(s) of each device installed in electrical equipment. These numbers and acronyms are to be used in drawings, elementary and connection diagrams, instruction books, publications, and specifications. The device number or acronym may be physically placed on, or adjacent to, each device on the assembled equipment.

¹ Notes in text, tables, and figures are given for information only and do not contain requirements needed to implement the standard.