March 2026: New IEC Power Quality Standard Enhances Electricity Supply Measurement and Assessment

The landscape of metrology and measurement for physical phenomena takes a major step forward this March 2026, with the publication of a pivotal new technical specification: IEC TS 62749:2026. This vital standard defines the expected characteristics of electricity supplied by public power networks across low, medium, and high voltages, as well as rigorous methods for the assessment of power quality. Covering one breakthrough standard this period, these updates are crucial for energy companies, compliance officers, engineers, and quality managers seeking to ensure reliable, high-quality electricity supply.

Overview / Introduction

Metrology and Measurement play a critical role in the stable, safe, and efficient distribution of electrical power around the globe. Physical phenomena impacting electricity—such as voltage fluctuations, frequency stability, harmonics, and quality indices—demand precise and consistent measurement approaches. International standards in this field support:

• Accurate cross-border and inter-company data exchange
• Regulatory compliance
• Infrastructure compatibility
• Technological innovation

This article explores the newest update from the International Electrotechnical Commission (IEC) that every professional in the electrical energy sector should be aware of—from utility operators and asset managers to engineers and procurement specialists.

Detailed Standards Coverage

IEC TS 62749:2026 – Assessment of Power Quality for Public Electricity Networks

Assessment of power quality – Characteristics of electricity supplied by public networks

Scope and Coverage:

IEC TS 62749:2026 sets out the landscape for assessing power quality at the point of supply in public low, medium, and high voltage networks (up to 230 kV, at both 50 Hz and 60 Hz). It delivers recommended values and indices for a wide range of phenomena that may affect the delivered electricity, including:

• Frequency and voltage deviations
• Voltage unbalance and flicker
• Harmonic and interharmonic voltages (clarified up to the 40th order)
• Voltage interruptions, dips, and swells
• Rapid voltage changes and transient overvoltage
• Mains communicating voltages and other disturbances

Measurement methods and result aggregation are carefully outlined, providing guidance on observation periods (weekly, 10-minute intervals) and statistical thresholds for percentile-based assessment, consistent with global best practices (referencing IEC 61000-4-30 and IEC 62586 series).

Who Should Comply:

• Electricity network operators (distribution and transmission)
• Utility planners and system maintenance teams
• Large industrial and commercial energy users (especially those at medium and high voltage)
• Manufacturers of measurement and monitoring equipment
• Regulatory authorities setting national or regional mains quality targets

Implementation and Key Changes from Previous Edition:

This third edition of IEC TS 62749 supersedes the 2020 version, with several notable changes:

• Explicit limitation of recommended harmonic orders to the 40th
• Enhanced clarity on applicability, confirming exclusion of networks above 230 kV
• Modified harmonic measurement and reporting (Clause 4.6)
• Improved methods and updated statistical profiles supporting multiple global regions
• Alignment with EN 50160:2022 and its 2025 amendment
• Deletion of Annex C for streamlined focus
• Refined section on mains communicating voltages and overall quality reporting

Practical Implications:

With these changes, operators and engineering teams must revisit their monitoring protocols and adjust reporting to reflect the new harmonic limits and improved data aggregation. National authorities may use the new statistical frameworks for power quality indices in regulatory frameworks and technical codes. Procurement and system design teams should ensure all new equipment and contracts reference the latest standard for continued compliance and risk minimization.

Key highlights:

• Harmonic measurement covered up to 40th order for 50 Hz/60 Hz systems
• Greater alignment with EN 50160 and European practices
• Inclusive guidance for global regions (Europe, China, Canada, Australia, Russia)

Access the full standard:View IEC TS 62749:2026 on iTeh Standards

Industry Impact & Compliance

Adopting the updated IEC TS 62749:2026 standard brings considerable benefits and responsibilities:

• Regulatory and contractual alignment: Standardized indices and measurement periods underpin utility contracts and satisfy national regulators across jurisdictions.
• Operational excellence: Consistent, documented approaches to power quality monitoring enhance reliability, minimizing outages, costly downtime, and customer complaints.
• Technical compatibility: Harmonized expectations for voltage, frequency, and harmonic distortion facilitate integration of distributed generation (e.g., renewables), electric vehicles, and smart grid technologies.
• Compliance timelines: Entities operating public supply networks must promptly adjust their assessment methodologies and reporting formats to comply with the expanded requirements. Transition planning is advised, considering the new harmonic limits and assessment procedures.

Risks of Non-Compliance:

• Potential regulatory penalties
• Increased risk of equipment damage and operational instability
• Reputational harm in energy supply reliability and customer satisfaction rankings
• Barriers to infrastructure upgrades and international partnerships

Benefits of Adopting the Standard:

• Enhanced reliability and customer trust
• Benchmarking and performance improvement
• Easier cross-border trading and network interconnection
• Facilitates technological innovation and smart grid deployments

Technical Insights

Common Technical Requirements:

All assessments and implementations under IEC TS 62749:2026 share certain essential features:

• Measurement based on international protocols: Use of 10-minute RMS intervals for most indices; aggregation and percentile statistics (typically 95–99%) for decisive evaluation.
• Harmonic voltage calculation: Explicit tables and values for individual and total harmonic distortion (THD), with clear differentiation between low, medium, and high voltage levels.
• Handling of flagged/extenuated data: Standard requires exclusion or careful treatment of flagged measurements (e.g., due to outages or disturbances).

Best Practices for Implementation:

1. Update Measurement Devices: Ensure all monitoring instruments have firmware and software capable of capturing harmonic orders up to the 40th and can apply new data aggregation methods.
2. Training and Awareness: Engage engineering and maintenance teams in updated measurement procedures and the rationale for new statistical assessment.
3. Stakeholder Coordination: Collaborate between network operators, users, and equipment suppliers to clarify mutual responsibilities (see Annex G of the standard).
4. Documentation and Reporting: Align internal quality reporting formats with those recommended, including percentile value calculations, event tracking, and compliance logs.
5. Review Connection Agreements: Amend existing power supply contracts to cite updated requirements and permissible voltage quality indices.

Testing and Certification:

• Measure against IEC 61000 series protocols for instrument performance and event data treatment
• Regular audit and review cycles to verify ongoing compliance with new thresholds and statistical approaches
• Document remediation measures and improvement plans where deviations are detected

Conclusion / Next Steps

The publication of IEC TS 62749:2026 marks a significant leap in the global measurement and management of electrical power quality. For all organizations involved in the supply or monitoring of public electricity networks, early adoption of these updated guidelines is not just prudent—it's essential.

Key takeaways:

• The standard enshrines best practices for voltage, frequency, and harmonic measurement
• Greater clarity and statistical rigor delivers improved coordination across regions and utility operators
• Implementation supports operational reliability, compliance, and technical innovation

Recommendations:

• Review monitoring infrastructure and contractual frameworks to ensure full compliance
• Train technical staff on new measurement and statistical evaluation methods
• Engage proactively with regulators and stakeholders about the transition plan

Explore all the latest metrology and power measurement standards, and stay informed on future updates at iTeh Standards.