TS EN 61666/A1

TS EN 61666/A1 is the Turkish adoption of EN 61666:2010/A1:2021, a standard concerned with identifying terminals within a system for industrial systems, installations, equipment and products. In practical terms, it addresses how terminal designations are handled so that diagrams, connection schedules and equipment documentation use the same terminology in a consistent way. A terminal designation tells users which conductor, connection point or functional interface belongs to which part of the system, reducing ambiguity during installation, commissioning and maintenance.

Why terminal identification matters in industrial documentation

Industrial equipment often contains multiple inputs, outputs and reference points on the same assembly. Clear terminal identification helps ensure that wiring, troubleshooting, servicing and replacement work are carried out against the correct connection. In general technical context, this is where symbols, reference marks and naming rules need to align across drawings and manuals. It is especially relevant in control cabinets, machine installations, automation equipment and technical product documentation, where consistency between documents is essential.

What this document provides as technical context

• The standard establishes a technical language for terminal identification tied to system position and function.
• It supports documentation consistency across industrial products, installations and equipment.
• The A1 designation shows that this listing belongs to an updated European/IEC amendment context.
• Its use sits within machine engineering and technical drawings, diagrams and related documentation.

This publication is better understood as a documentation and identification standard than as a product performance standard. In practice, reliable terminal marking improves readability of records, helps reduce connection mistakes and makes documentation from different manufacturers easier to compare and use.