May 2025 Monthly Overview: Metrology and Measurement Standards in Review (Part 1)

Looking back at May 2025, the Metrology and Measurement sector—specifically within the realm of physical phenomena—witnessed the release of several pivotal standards set to shape the field’s operational, compliance, and innovation practices. This comprehensive overview (part one of two) synthesizes the main themes, technical advances, and compliance implications across five significant standards published during the period. For industry professionals, engineers, compliance officers, and researchers aiming to remain at the leading edge, this digest offers analysis that bridges the technical content with actionable context and future-facing insight.

Monthly Overview: May 2025

May 2025 demonstrated a focused standardization activity in Metrology and Measurement of Physical Phenomena, with updates stretching across electrical safety, precision instrumentation, renewable energy, advanced insulation, and electrostatic management. The diversity of the standards—covering everything from high voltage safety for instrument transformers to advanced vibration evaluation for wind turbines—reflects an industry attentive to both evolving regulatory demands and rapid technological development.

Compared to prior months, this release window stood out for its balanced mix of foundational updates (such as dimensional interchangeability for panel-mounted instruments) and specialized advances (like uncertainty guidance for electrostatic measurements). Emerging trends pointed to:

• Heightened emphasis on safety in high-energy and high-voltage applications
• Greater precision and reliability in diagnostics and monitoring, especially for renewable energy sectors
• Modernized methodologies to ensure measurement quality and traceability as complexity increases

This monthly collection serves as an essential checkpoint for organizations reinforcing measurement integrity, adapting to new compliance requirements, or charting strategic investments in cutting-edge instrumentation.

Standards Published This Month

EN IEC 61869-20:2025 - Safety Requirements for Instrument Transformers for High Voltage Applications

Instrument transformers – Part 20: Safety requirements of instrument transformers for high voltage applications

This essential standard defines the safety requirements for the design, operation, and testing of instrument transformers intended for high-voltage equipment (exceeding 1 kV AC or 1.5 kV DC). Notably, it specifically excludes low power instrument transformers, focusing instead on the safety-critical devices widely used in power transmission, distribution, and protection systems.

Key prescriptive areas include:

• Protective measures against electric shock—encompassing detailed earthing methodologies for various transformer types and scenarios
• Thermal and chemical hazard mitigation, such as assessment of fire, internal arcing, and fluid or gas leakage risks
• Mechanical hazard protections—both during routine operation and mounting/dismounting processes
• Reference to harmonized safety and compatibility standards for enclosures (IP and IK codes)

Industries and organizations affected span energy utilities, high-voltage laboratories, substation manufacturers, compliance bodies, and any operators responsible for transmission infrastructure. The standard’s alignment with the broader EN IEC 61869 series ensures seamless integration into existing regulatory frameworks.

Key highlights:

• Comprehensive electric shock protection protocols for both indoor and outdoor units
• Specific risk mitigations for open or short-circuited secondary terminals
• Cross-references with IP/IK code standards for enclosure protection

Access the full standard:View EN IEC 61869-20:2025 on iTeh Standards

ISO 20816-21:2025 - Vibration Measurement and Evaluation for Horizontal Axis Wind Turbines

Mechanical vibration — Measurement and evaluation of machine vibration — Part 21: Horizontal axis wind turbines

This new part in the ISO 20816 series establishes methods for measuring and evaluating vibrations in horizontal axis wind turbines—encompassing both traditional gearbox-coupled setups and advanced direct-drive configurations, with turbine generator outputs above 200 kW. The document provides clarity on measurement methodologies, defining:

• Vibration measurement positions (nacelle, tower, rotor, gearbox, generator)
• Requirement of standardized frequency bands and data capture methods
• Evaluation zones for vibration magnitude across various operating conditions
• Limit values to guide safe, long-term operation and comparative assessments between wind turbines

Of note, the annexes compile empirical evaluation zone boundaries, aiding user-manufacturer discussions on early fault detection—critical for maximizing uptime and minimizing lifecycle cost. While the standard does not cover diagnostic or acceptance testing of individual gearboxes/generators, it references complementary standards and literature (e.g., ISO 13373, ISO 16079, IEC 61400-13) for broader condition monitoring.

Primary users include wind energy operators, engineers tasked with O&M, vibration analysts, renewable energy compliance bodies, and instrument suppliers for wind turbine diagnostics.

Key highlights:

• Differentiation and tailored evaluation for gearbox versus direct drive turbine architectures
• Rigorous guidance for both measurement techniques and zone boundary evaluation
• Integration with established condition monitoring best practices

Access the full standard:View ISO 20816-21:2025 on iTeh Standards

IEC 61554:2025 - Panel Mounted Equipment: Dimensions for Panel Mounting

Panel mounted equipment – Electrical measuring instruments – Dimensions for panel mounting

The newly revised IEC 61554:2025 defines standardized panel mounting dimensions and tolerances for a broad class of electrical measuring instruments and control equipment. Ensuring dimensional interchangeability allows users to efficiently combine instruments from multiple manufacturers and optimize panel space—facilitating smoother upgrades, replacements, and panel design.

Key scope and features include:

• Applicable to instruments with square, rectangular (lateral/upright), and round housings (with square or rectangular bezel options)
• Defined cut-out and bezel sizes/tolerances to promote compatibility and future-proofing
• Updated normative annex consolidating housing dimensions and practical guidelines for common and individual cut-out scenarios
• Alignment with ISO 2768-1 for general tolerance practices

This standard chiefly benefits panel builders, switchgear manufacturers, control system integrators, and procurement specialists tasked with ensuring reliable sourcing and streamlined assembly of metering and monitoring equipment.

Key highlights:

• Inclusion of new size options and revised tolerances for enhanced instrument fit
• Practical methodologies for calculating common cut-out dimensions when grouping devices
• Clarification of instrument and bezel sizing nomenclature

Access the full standard:View IEC 61554:2025 on iTeh Standards

IEC 60684-2:2025 - Flexible Insulating Sleeving: Methods of Test

Flexible insulating sleeving – Part 2: Methods of test

This major revision of IEC 60684-2 offers a broad update to the test methods for flexible insulating and heat-shrinkable sleeving, which are vital for insulating electrical conductors, apparatus connections, and increasingly diverse applications in electronics and automotive sectors.

Highlights of the update include:

• Expanded and clarified test procedures for bore and wall thickness (including newly differentiated methods for braided, textile, and extruded sleeving)
• Added or revised tests for longitudinal change, flame propagation (now with additional method D), abrasion resistance, volume resistivity for semi-conducting materials, and outgassing
• Major overhaul of normative references and introduction of new procedures for sample preparation (notably, adhesive peel and weathering resistance testing)

The document remains focused on quality control, not establishing suitability for penetration, encapsulation, or highly specialized applications. Supplementary tests remain necessary for those contexts, reinforcing the importance of situational compatibility assessment.

Key stakeholders include cable and wiring harness manufacturers, OEMs across electrical, electronics, and automotive sectors, laboratory testers, and quality assurance managers.

Key highlights:

• Comprehensive rewrites and clarifications in key test methods
• New and refined procedures supporting modern material profiles, including semi-conductive and weather-resistant variants
• Added focus on physical property retention under mechanical and environmental stress

Access the full standard:View IEC 60684-2:2025 on iTeh Standards

IEC TR 61340-1-1:2025 - Electrostatics: Measurement Errors, Uncertainties, and Expression of Results

Electrostatics – Part 1-1: Electrostatic phenomena – Measurement errors, uncertainties and expression of results

Given the increased sensitivity of today’s electronics and cleanroom environments, this technical report provides critical, practical guidance for minimizing measurement errors and evaluating uncertainties in electrostatic and electrostatic discharge (ESD) control scenarios. Building on the IEC 61340 series, the document details:

• Classification of measurement errors (random, systematic, gross)
• Practical steps for minimizing errors during resistance, charge, voltage, and field measurements
• Approaches for evaluating and expressing measurement uncertainty and data confidence in test reporting
• The proper use of significant digits, units, symbols, and calibration traceability

Although intended as guidance for competent professionals already experienced in electrostatic measurements, this report will be valuable for auditing, verifying compliance, and improving laboratory methods in any ESD-aware industry.

Key highlights:

• Practical error classification and real-world mitigation advice
• Detailed procedures for uncertainty estimation and laboratory best practices
• Recommendations for standardized expression of test results in reports

Access the full standard:View IEC TR 61340-1-1:2025 on iTeh Standards

Common Themes and Industry Trends

The portfolio of May 2025 standards reveals an industry at the intersection of safety, interoperability, and heightened performance accountability. Safety is significantly reinforced, especially with the push for more robust high-voltage transformer requirements and improved test methods for insulation. Measurement quality and consistency—whether in vibration analysis, panel instrumentation, or electrostatics—emerges as a unifying thread, with new standards driving:

• Convergence on globally harmonized procedures (especially for measurement, evaluation, and reporting)
• Explicit consideration for modern materials and advanced energy systems (wind turbines, semi-conductive sleeving, ESD-prone environments)
• Broader guidance for integrating data quality and uncertainty into compliance and reporting workflows

Sectors experiencing the most attention include power transmission and distribution, renewable energy (particularly wind power), and electronics manufacturing. The increasing complexity of system architectures across these industries is matched by a rise in precision and traceability requirements in measurement and diagnostic practices.

Compliance and Implementation Considerations

Organizations affected by these standards are encouraged to:

1. Review compliance against updated safety protocols, especially for high voltage installations and equipment panels, to safeguard against regulatory misalignment and operational hazards.
2. Upgrade diagnostic and monitoring systems—notably vibration analysis setups for wind energy assets—to reflect standardized limits, zone evaluations, and measurement procedures.
3. Assess laboratory test protocols and documentation against updated test and reporting methods, incorporating uncertainty estimation into the quality management system as guided in the new electrostatics technical report.
4. Coordinate with suppliers and manufacturers to ensure new and replacement instruments, panel equipment, and insulating materials conform to the latest interchangeability and test standards.

Implementation priorities may include:

• Immediate review and alignment of safety documentation and operational procedures
• Training on revised test methods and vibration evaluation criteria
• Transition plans for phasing in new dimensions, tolerances, and reporting requirements
• Leveraging technical support and official guidance from standards bodies

Timelines should factor in both the effective dates of these standards and any organization-specific change management periods. Early action will minimize disruption and support continual improvement.

Resources for getting started:

• Full standards access via iTeh Standards
• Cross-functional team meetings to review impacted processes
• Participation in relevant industry and technical committees for up-to-date best practices

Conclusion: Key Takeaways from May 2025

May 2025 stands as a landmark month in Metrology and Measurement of Physical Phenomena, producing a diverse set of publications that reinforce safety, elevate diagnostic precision, and clarify the pathway to robust, interoperable infrastructures. The most impactful changes came in:

• Elevated safety standards for instrument transformers
• Modernized vibration evaluation frameworks for wind energy assets
• Updated and harmonized sizing for panel-mounted instruments
• Comprehensive new and refined tests for insulating sleeving
• Improved practical guidance for error reduction and uncertainty estimation in electrostatics

For industry professionals, vigilance in keeping pace with these changes ensures not only compliance, but a foundation for innovation, operational excellence, and quality. Staying current with standards—supported by detailed analysis and trusted resources like iTeh Standards—empowers organizations to outpace risk, unlock efficiencies, and drive industry leadership.

Further reading and exploration is highly recommended—see the individual standards linked throughout this overview for a deeper technical dive.