Overview
IEC 61061-1:2006 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies the definitions, designation, and general requirements for non-impregnated densified laminated wood used for electrical purposes. This Part 1 of the IEC 61061 series serves as the foundational document for understanding the material types covered in the subsequent parts.
The standard applies to sheets and rings of laminated wood with nominal thicknesses ranging from 6 mm to 100 mm. It ensures that the laminated wood meets performance and safety requirements suitable for electrical insulation applications, especially where resistance to transformer oils and mechanical integrity are critical.
Key updates in this edition include:
- Addition of application use and safety statements
- Redefinition of ring and sheet classifications
- Additions to detailed technical subclauses
- Reformatting to align with current IEC document structure
Key Topics
Definitions and Terms
Clear terminology is provided for:
- Veneer: individual plies of wood, typically not thicker than 2.5 mm before pressing
- Non-impregnated densified laminated wood: layers of wood veneers bonded with thermosetting synthetic resin under heat and pressure, without impregnation
- Sheet and ring forms: sheets have parallel or crosswise veneer arrangements; rings may be formed by cutting or pressing veneers in tangential or angled layouts
- Directions "A" and "B" define orthogonal planes in laminated sheets
Material Designation
The standard outlines a structured designation system based on:
- Shape (Sheet or Ring)
- IEC standard number (61061)
- Veneer arrangement type (P for parallel, C for crosswise, T for tangential, A for 45° angled)
- Density class (1 to 4 indicating increasing apparent density ranges from 0.7 to 1.3 g/cm³)
- Wood type (B for birch, M for maple, R for beech)
- Dimensions (thickness, width, length for sheets; thickness, radial width, outer diameter for rings)
General Requirements
The standard mandates:
- Use of wood veneers and resin resistant to transformer oils, ensuring no detrimental effects during operation
- Free from defects such as diseased areas or electrically conductive inclusions; fibre direction must be controlled
- Finished sheets must be flat, smooth, with tightly butted veneer joints; rings must also have close joints free from significant gaps
- Thickness tolerances and flatness requirements as per referenced test methods (IEC 61061-2 and IEC 61061-3)
- Material machinability ensuring no chipping, splitting, or cracking when processed carefully
Safety and Application Statements
Users must ensure safe handling, use, and application of these materials. Selection should be based on specific application requirements beyond just compliance with the specification.
Applications
Non-impregnated densified laminated wood is widely used in electrical insulation systems, notably in:
- Transformers and switchgear components where mechanical strength and electrical insulation are critical
- Components exposed to transformer oils requiring material compatibility and chemical resistance
- Insulation sheets and rings that support electrical devices by providing compression strength and thermal stability
- High voltage equipment laminations where dimensional stability and resistance to oil ingress are required
This standard supports manufacturing and quality assurance processes, helping manufacturers and purchasers specify and verify appropriate laminated wood products for electrical uses.
Related Standards
IEC 61061-1:2006 is part of a series addressing densified laminated wood for electrical purposes:
- IEC 61061-2: Methods of test for non-impregnated densified laminated wood
- IEC 61061-3: Specifications for individual materials within this product group
- IEC 60296: Standard on unused mineral insulating oils for transformers and switchgear, referenced for material compatibility
- Other IEC standards associated with solid electrical insulating materials
These standards together provide a comprehensive framework governing the production, testing, and use of non-impregnated densified laminated wood in electrical engineering applications.
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