TS 855 EN 60071-1

TS 855 EN 60071-1 is a standard on insulation co-ordination, focused on definitions, principles and rules for electrical power systems. It provides a common technical framework for three-phase AC systems whose highest voltage for equipment is above 1 kV. In general engineering terms, insulation co-ordination is the discipline of matching equipment insulation strength with the overvoltages that may occur in service.

What insulation co-ordination addresses

The core idea is to select and arrange insulation so that equipment can withstand normal operating voltages as well as transient stresses such as switching or lightning-related overvoltages. This involves understanding how insulation level, clearances, dielectric strength and system voltage stress relate to one another. As general technical context, it is a design and system-planning concept that helps different items of equipment operate compatibly within the same network.

System boundary covered by this standard

• Three-phase AC systems
• Highest voltage for equipment above 1 kV
• Definitions and key terminology
• Principles and rules for insulation co-ordination

As Part 1 of the insulation co-ordination series, this document serves as the foundational section for the subject. In high-voltage engineering, precise terminology matters because voltage classes, overvoltage types and insulation design choices are closely linked. This TSE edition is withdrawn, but it remains useful for understanding the historical technical framework of the field.