IEEE C37.2 – 2008 Standard Revisions

The advancement in technology have influenced the changes to the IEEE C37.2, one of the oldest IEEE standards still being used today. This standard began life as AIEE No.26 in 1928. Even IEC designers have used IEEE C37.2 device function numbers in their diagrams one way or another as it clearly defines the functions of devices. Device 52 is well known as an AC circuit breaker; 52a is recognized as a normally open auxiliary contact on an ac circuit breaker; 50 is an instantaneous overcurrent relay; 27 is an undervoltage relay, and 79 is a reclosing relay. These five functions, and almost ninety more, have been defined in IEEE C37.2 for years.

The new title is IEEE C37.2 – 2008 Standard for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations. This was the first revision to IEEE C37.2 since 1996. There are substantial additions in this 2008 revision that will be of particular value to those adding Ethernet communications to substation control and protective relaying systems.

Summary of changes to IEEE C37.2-2008:

  • Added seventeen acronyms for new functions
  • Used device #16 and a unique set of suffixes for substation communication networking devices.
  • Added ten new suffix letter combinations to more completely define functions
  • Added a List Box method to describe the contents of a multifunction device 11
  • Added a Coordinated Trip & Close Fusing elementary diagram
  • Added a comprehensive three page cross reference table to IEC 61850 logical nodes


  1. IEEE Group
  2. IEEE Committee