Overview
IEC TR 63519:2024 - "Aspects and understanding of measurement uncertainty" is a Technical Report from IEC TC 85 (Measuring equipment for electrical and electromagnetic quantities). It provides background information on measurement uncertainty (MU) terminology and general concepts, with a focus on practical application for electrical and electromagnetic measuring equipment. The report explains how MU affects metrological compatibility, metrological traceability, conformity assessment and decision-making, and illustrates concepts with examples (e.g., insulation resistance per IEC 61557-2).
Key topics and requirements
- Terminology and concepts: Clear definitions of probability distribution, probability density function (PDF), calibration, and metrological compatibility as used in electrical metrology.
- Uncertainty evaluation approach: Describes the statistical approach of the Guide to the expression of uncertainty in measurement (GUM/ISO/IEC Guide 98‑3), including the need to identify influence quantities and their PDFs.
- Characterization of influence quantities: Examples (resolution shown as a uniform distribution) and how component PDFs combine - typically tending toward a normal (Gaussian) distribution via the central limit theorem.
- Expression of MU: Use of standard deviation and coverage factors (commonly k = 2 for ≈95% confidence) to report uncertainty alongside measured values.
- Decision and conformity implications: Role of MU in determining metrological compatibility, calculating probabilities such as probability of false acceptance (PFA) and probability of false rejection, and applying MU in conformity assessments.
- Traceability and compatibility: Discussion of metrological traceability (pyramid concept) and how MU supports traceability chains and comparability between measurements.
- Worked examples: Practical calculation examples (insulation resistance) and discussion of improvement via control of influence quantities.
Applications
- Use for manufacturers of electrical test and measurement equipment to understand how to report and control measurement uncertainty.
- Guidance for calibration laboratories and test houses to evaluate and express MU consistent with IEC TC 85 practice.
- Support for conformity assessors and certification bodies when making go/no-go decisions that depend on uncertainty and probabilities (e.g., PFA/PFR).
- Reference for standards developers and technical committees integrating MU requirements into product standards and test methods.
Who should use this standard
- Calibration and metrology laboratories, test engineers, product manufacturers, conformity assessment bodies, and standards writers working with electrical and electromagnetic measuring equipment.
Related standards and documents
- ISO/IEC Guide 98‑3:2008 (GUM) - Guide to the expression of uncertainty in measurement
- IEC 61557‑2 (example used in the report) - insulation resistance measurements
- ISO/IEC Guide 99 (VIM) - vocabulary for metrology
Keywords: measurement uncertainty, IEC TR 63519:2024, metrological traceability, metrological compatibility, GUM, probability density function, conformity assessment, IEC TC 85.