IEC 60404-7:2019

Overview

IEC 60404-7:2019 is an international standard issued by the International Electrotechnical Commission (IEC) that specifies a standardized method for measuring the coercivity of magnetic materials in an open magnetic circuit. This document applies to magnetic materials with coercivities ranging from 0.2 A/m to 160 kA/m, encompassing a broad spectrum of magnetic alloys including amorphous alloys, nanocrystalline alloys, soft magnetic crystalline materials (such as Fe, FeSi-, CoFe-, and FeNi-based alloys), soft ferrites, hard metals, and semi-hard magnetic alloys like FeCoTiAl, FeCoV, FeCrCo, and AlNiCo alloys.

The 2019 edition introduces critical updates to improve measurement accuracy and broaden applicability, including enhanced compensation for environmental magnetic noise and detailed handling of test specimens with various shapes.

Keywords: IEC 60404-7, magnetic materials, coercivity measurement, open magnetic circuit, magnetic alloys, magnetic testing standards, coercive field strength.

Key Topics

• Scope and Applicability:
  Applies to all magnetic materials with coercivity values between 0.2 A/m and 160 kA/m. Special procedures are outlined for materials with low coercivities (<40 A/m) and non-ellipsoidal test specimen shapes.

• Measurement Principle:
  The standard details methods to measure coercivity, defined as the coercive field strength when magnetic flux density or polarization is reduced from saturation to zero, using an open magnetic circuit setup.

• Measurement Methods:
  The document includes multiple methods:

  • Method A and B - Employ flux sensing probes such as Hall probes or differential fluxgate probes inside the solenoid, with methods separated for local and integral flux measurements.
  • Method C - Uses a Vibrating Sample Magnetometer (VSM), now described in Annex B, offering an alternative measurement technique.

• Technical Enhancements:
  Updates feature:

  • Simplified circuit diagrams with added fluxgate probes inside the solenoid for enhanced measurement precision.
  • Compensation techniques for Earth’s magnetic field and mitigation of static and dynamic magnetic noise for greater accuracy.
  • Magnetic shielding of the measurement region to minimize external magnetic interference.
  • Clear differentiation between measurements for local flux and integral flux in specimens, including considerations for specimen size and shape.
  • Revised terminology replacing "complex shaped test specimen" with "test specimen different from ellipsoids" for clarity.

• Test Specimen Requirements:
  Provisions advise on specimen form factors, with specific attention to shapes that influence flux measurement, as well as special precautions when testing materials with low coercivity or high electrical conductivity.

Applications

IEC 60404-7:2019 serves as a fundamental reference for laboratories, manufacturers, and researchers engaged in:

• Accurate characterization of magnetic properties in advanced materials used in electronics, electrical machinery, sensors, and magnetic storage devices.
• Quality control and conformity testing of magnetic alloys and composites in industrial production.
• Research and development environments evaluating new magnetic materials or coatings, ensuring compliance with globally recognized measurement protocols.
• Facilitating consistency in coercivity measurement for magnetic materials used in power generation, transformers, and telecommunications.

The standard's comprehensive approach to noise compensation and specimen handling extends applicability to diverse materials and complex testing environments, ensuring reliable coercivity data essential for magnetic design and engineering.

Related Standards

IEC 60404-7:2019 is part of the broader IEC 60404 series on magnetic materials and is closely related to:

• IEC 60404 (general series): Covers magnetic material testing methods and terminology.
• Other parts of IEC 60404 series addressing specific material types or magnetic properties such as permeability, remanence, and hysteresis.
• ISO and IEC Electropedia - For standardized definitions and terminology related to electromagnetic and magnetic materials.
• Industry-specific standards that may reference IEC 60404-7 as a benchmark for coercivity testing and magnetic material qualification.

For those implementing IEC 60404-7, staying current with the latest editions and complementary standards in magnetic materials ensures best practices and conformity in material characterization.

For accurate coercivity measurement in magnetic materials, IEC 60404-7:2019 provides essential guidance, promoting precision, repeatability, and harmonization in the global electrotechnical community.