Introduction to the History of Selective Protection

Author: Walter Schossig, Germany

The Language of Engineers

As the electric industry expanded it soon became essential to establish a common set of terms, standards, rules and regulations to allow effective communication between engineers.

Engineers communicate with drawings - they have done so in the past, are doing so now, and will continue to do so in the future. The first harmonization of symbols took place in 1928 and ten years later the first International Electrotechnical Vocabulary (IEV) was published by the International Electrotechnical Commission (IEC) (The IEC was founded in June 1906, in London, England).


Figure 8 Symbol TOC-Relay 1928




Figure 9 The first IEV 1938

The American Institute of Electrical Engineers (AIEE) (now IEEE) (The AIEE was a United States based organization of electrical engineers that existed between 1884 and 1963. It merged in 1963 with the Institute of Radio Engineers (IRE) to form the Institute of Electrical and Electronics Engineers (IEEE)) introduced codes for the description of protection functionalities in 1928. For many years the use of American National Standards Institute (ANSI) / IEEE codes was limited to the Americas however the codes are now being used all over the world. Some of you, dear readers, might remember the block diagrams from the 30's - you know how to value modern drawings, right?

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BeijingSifang June 2016