Overview
IEC TR 62581:2010 - "Electrical steel: Methods of measurement of the magnetostriction characteristics by means of single sheet and Epstein test specimens" - is a technical report that defines practical measurement principles and test procedures for magnetostriction in electrical steel. The document describes measurements using single sheet (preferably 500 mm × 100 mm) and Epstein strip specimens (as specified in IEC 60404-2) and covers optical and accelerometer-based measurement techniques. Tests are performed for a sinusoidal excitation at specified peak magnetic polarization and frequency, on demagnetized specimens at an ambient temperature of 23 °C ± 5 °C.
Key topics and technical requirements
- Test specimens: single sheet dimensions recommended and Epstein strip format in accordance with IEC 60404-2.
- Measurement methods: optical sensors (interferometers, laser Doppler vibrometers, laser displacement meters) and accelerometers, including single-point and differential arrangements.
- Test conditions: sinusoidal induced voltage, defined peak values of magnetic polarization, specified frequency, demagnetized specimens, ambient temperature 23 °C ± 5 °C.
- Instrumentation and setup: yoke designs, windings, air flux compensation, power supply, optical sensor placement, stressing devices, and data acquisition systems.
- Data processing and metrics: extraction of the magnetostriction “butterfly loop,” determination of zero‑to‑peak and peak‑to‑peak magnetostriction values, averaging and reproducibility methods.
- Effects and sensitivities: influence of applied stress, coating tension, specimen reset, overlap length, gap between specimen and yoke, environmental noise and averaging on measurement precision.
- Supplementary analysis: models relating magnetostriction to domain structure and stress; guidance on preventing out-of-plane deformations; A‑weighted acoustic considerations (referencing IEC 61672‑1).
Practical applications and target users
IEC TR 62581 is intended for:
- Materials and metallurgical engineers evaluating magnetostriction in electrical steel grades (grain‑oriented and non‑oriented).
- Transformer, motor and generator designers concerned with core vibration and audible noise resulting from magnetostriction.
- Test laboratories and quality control teams implementing standard measurement protocols for supplier acceptance and R&D.
- Acoustic and vibration specialists assessing how magnetostrictive strain translates to noise and mechanical stress sensitivity.
Using the standardized methods helps compare magnetostriction across materials and process variants (e.g., coatings, stress states), improving design decisions for low‑noise and high‑performance electromagnetic devices.
Related standards
- IEC 60404-2 (Epstein strip specimen requirements for magnetic measurements)
- IEC 61672-1 (A‑weighting, referenced for A-weighted magnetostriction acoustic metrics)
Keywords: IEC TR 62581, magnetostriction, electrical steel, single sheet tester, Epstein strip, optical sensors, accelerometers, measurement methods, butterfly loop, magnetostrictive strain.