This Technical report provides recommendations for consistent use of mnemonics and qualifying symbols to be applied to symbols representing devices used in systems for monitoring, protection, switching, and controlling of apparatus in electrical substations, generating stations, power utilization and conversion facilities, and equipment designed for automatic protection of power systems. The recommendations are intended for designers, manufacturers and engineers of such systems.For symbols of measuring relay and measuring instrument, it is intended to serve two purposes,namely:— It gives a review of standardized designations;— It is intended to limit the ra