IEC TR 62711:2011

Overview

IEC TR 62711:2011 - "Mnemonics and designations of symbols for measuring relays, instruments and related device" is a Technical Report from the IEC that provides recommendations for the consistent use of mnemonics and qualifying symbols applied to graphical representations of measuring relays and measuring instruments. It targets devices used in monitoring, protection, switching and control of apparatus in electrical substations, generating stations, power conversion facilities and automatic protection equipment for power systems.

This report is advisory (technical report) and complements the graphical symbol rules of IEC 60617 and the design guidance in ISO/IEC 81714-1.

Key topics and requirements

• Purpose: standardize mnemonics and designations so symbols are consistent and unambiguous across drawings and documentation.
• Symbol usage:
  • Use the general measuring-relay symbol (IEC 60617‑S00327) and combine it with appropriate supplementary/qualifying symbols.
  • Use the general measuring-instrument symbols (IEC 60617‑S00910 / S00911 / S00912) and replace the asterisk with the relevant letter/graphical designation.
• Mnemonics tables: comprehensive tables (Tables 1–19) list permitted prefixes, suffixes, general, current, voltage, frequency, impedance, power, phase and other designations for relays and instruments.
  • Example prefix/suffix mnemonics (from the report): O (over), U (under), B (band); suffixes B (balance), V (with voltage restraint).
  • Examples of relay designations: D (directional), Df (differential), RDf (ratio/percentage differential), G (ground relay).
• Normative references and alignment: links to IEC 60617, IEC 60909 (designation variables), and ISO/IEC 81714‑1 are provided for correct symbol construction and application notes.

Practical applications and users

Who uses IEC TR 62711:

• Substation and protection engineers
• Power system designers and schematics authors
• Relay and instrument manufacturers
• Technical authors preparing wiring diagrams, single-line diagrams and maintenance documentation

Practical benefits:

• Improves clarity and interoperability of protection & control diagrams.
• Reduces ambiguity in procurement, testing and maintenance documents.
• Helps manufacturers label devices and front-panel instruments consistently for global projects.

Related standards

• IEC 60617 - Graphical symbols for diagrams (primary symbol source)
• ISO/IEC 81714‑1 - Design of graphical symbols for product documentation
• IEC 60909, IEC 60050 - referenced for designation variables and terminology

Keywords: IEC TR 62711:2011, mnemonics, designations, measuring relays, measuring instruments, symbols, IEC 60617, electrical substations, protection diagrams.