TS 2138 IEC 27-1

TS 2138 IEC 27-1 is a general standard for letter symbols used in electrical technology, covering the symbols for quantities and units and the rules for writing, combining, and presenting them. In engineering documents, calculations, and technical drawings, consistent symbol usage helps prevent the same quantity from appearing in different forms across sources and supports a common reading of formulas, text, and diagrams.

Letter symbols and notation rules

In electrical engineering, letter symbols provide a compact and standardized way to represent physical quantities and their units, such as current, voltage, resistance, and power. Standards of this kind organize how symbols are chosen and combined, including details such as subscripts, singularity functions, distributions, and letter styles. The practical goal is not only readability, but also a stable technical meaning whenever a symbol appears in a formula or diagram.

Role in electrical technical documentation

In general technical context, the value of this kind of standard is that engineers in different disciplines can use the same symbols with the same meaning. Electrical quantities often appear in system equations, measurement records, control diagrams, and equipment labeling, so even small differences in notation can lead to misinterpretation. TS 2138 IEC 27-1 provides a common reference framework for that shared notation.

This record is based on IEC 27-1:1992 and is now withdrawn. It therefore serves as a historical reference for letter-symbol usage in electrical technology and is relevant to users working with terminology, technical documentation, or legacy references.