Overview
IEC 60763-2:2007 - Specification for laminated pressboard - Part 2: Methods of test - defines standardized test methods for laminated pressboard used as an electrical insulating material. It applies to materials classified in IEC 60763-1 and provides reproducible procedures for mechanical, electrical, thermal and chemical characterization needed for quality control, type testing and specification compliance. This second edition (2007) was editorially revised to align with IEC 60641-2, replaces the internal ply strength test with an alternative method, and enlarges the scope of thermal resistance testing.
Key topics and technical requirements
The standard contains detailed, repeatable test procedures covering:
- Specimen conditioning and drying
- Conditioning: 23 °C ± 2 K, 50 % ± 5 % RH until moisture 5.5–8 % (approached from dry side).
- Drying Method A (preferred): 105 °C ± 2 K, 24 h in forced-air oven + 48 h at 105 °C ± 2 K in vacuum ≤ 1 kPa.
- Drying Method B: 105 °C ± 2 K, 168 h in ventilated oven (alternative).
- Dimensions and thickness measurement
- Defined micrometer requirements (measuring face diameter, flatness, graduation and applied pressure) and measurement points.
- Mechanical tests
- Flexural strength, load to produce standard deflection, apparent modulus of elasticity in flexure, compressibility.
- Electrical tests
- Electric strength in oil (including edgewise/along-laminate testing) and related conditioning.
- Interlaminar/internal ply strength, thermal resistance and oil compatibility
- Updated methods for internal ply strength and expanded thermal resistance testing scope.
- Physical and chemical properties
- Apparent density, moisture content, shrinkage after drying, oil absorption, ash content.
- Compatibility and contamination
- Methods to assess contamination of liquid dielectrics, conductivity and pH of aqueous extracts.
(The standard references related test methods in IEC 60243‑1, IEC 60641‑2, IEC 60296, ISO 287, ISO 2144, among others.)
Practical applications and users
IEC 60763-2 is essential for:
- Manufacturers of laminated pressboard and pressboard-based components (transformer spacers, barriers, insulating supports).
- Test laboratories performing type, acceptance and failure-analysis testing.
- Design and specification engineers in transformer, switchgear and electrical equipment industries who need validated material data (mechanical strength, dielectric performance, thermal resistance).
- Procurement and quality assurance teams ensuring supplier compliance and repeatability across batches.
Using these methods ensures consistent evaluation of mechanical integrity, dielectric behaviour in oil, thermal performance and chemical compatibility - critical for long-term reliability of high-voltage equipment.
Related standards
Keywords: IEC 60763-2:2007, laminated pressboard, methods of test, electrical insulation, transformer components, dielectric strength, thermal resistance, internal ply strength, pressboard testing.
