IEC 62975:2021

Overview

IEC 62975:2021 – Natural esters – Guidelines for maintenance and use in electrical equipment provides comprehensive procedures and best practices for the use and maintenance of natural ester liquids in sealed transformers and other types of electrical equipment. Issued by the International Electrotechnical Commission (IEC), this international standard is pivotal for operators and maintenance professionals aiming to ensure the safety, efficiency, and environmental compliance of insulating liquids derived from natural esters.

Focusing on equipment originally filled with natural esters conforming to standards such as IEC 62770 and ASTM D6871, IEC 62975:2021 outlines standardized approaches for monitoring, testing, and maintaining the quality of these fluids. The document is particularly relevant for applications where liquid sampling is practical, and the normal operating conditions specified by the manufacturer are observed.

Key Topics

• Scope of Application:

  • Sealed power transformers, reactors, switchgear, and electrical apparatus utilizing natural ester-based insulation fluids.
  • Electrical equipment for which regular sampling and quality checks on insulating liquid are feasible.

• Maintenance Guidelines:

  • Procedures for ongoing surveillance and testing of natural ester liquids to detect deterioration, contamination, or operational risks.
  • Recommendations for the selection and frequency of diagnostic and complementary tests, such as breakdown voltage, acidity, dissipation factor, and water content.

• Evaluation and Condition Assessment:

  • Methods for assessing the quality of new and in-service natural esters.
  • Practical guidance on interpreting test results and establishing action limits to trigger maintenance interventions.
  • Strategies for trend analysis and risk management.

• Corrective and Preventive Actions:

  • Guidance for reconditioning, reclaiming, or replacing natural esters if quality thresholds are exceeded.
  • Procedures for proper sampling, handling, and disposal in compliance with local regulations and environmental standards.

• Preparation of Local Codes of Practice:

  • Framework for developing site-specific or national maintenance codes based on a harmonized international approach.

Applications

• Power Transformers: The primary application is in sealed or hermetically protected transformers used throughout electrical power generation, transmission, and distribution networks. Maintenance guidelines help maximize transformer longevity and minimize unplanned outages by ensuring fluid integrity.

• Switchgear and Instrument Transformers: While less information is available for equipment other than transformers, the document gives initial recommendations extendable to switchgear and other electrical apparatus where practical.

• Industrial Electrical Equipment: Operators of industrial facilities benefit from a structured approach to insulating liquid management, supporting safety, operational continuity, and environmental stewardship.

• Condition Monitoring: The standard assists operators in setting up routine and advanced monitoring programs, including diagnostic testing and trend analysis, which are crucial for risk-based maintenance.

Related Standards

Operators and maintenance professionals are encouraged to reference the following standards in conjunction with IEC 62975:2021 for a comprehensive approach:

• IEC 62770: Unused natural esters for transformers and similar electrical equipment – Specifies requirements for new fluids.
• IEC 60156: Test method for breakdown voltage.
• IEC 60814: Determination of water content using Karl Fischer titration.
• IEC 60247: Measurement of dielectric dissipation factor and d.c. resistivity.
• IEC 60567: Guidance on dissolved gas analysis.
• ASTM D6871: Natural ester fluid specification for transformers.
• Additional references such as ISO 2049, ISO 3104, and other IEC and ASTM methods are cited within the standard for specific tests.

Practical Value

Implementing IEC 62975:2021 ensures:

• Enhanced reliability and operational safety of electrical equipment utilizing natural ester insulating liquids.
• Extended service life of transformers through appropriate maintenance and diagnostics.
• Improved environmental performance via the use of biodegradable natural esters and compliant waste management.
• Global harmonization of maintenance practices, supporting operators in international and multi-site industries.

By following the guidelines in IEC 62975:2021, electrical equipment operators uphold best practices for insulating liquid maintenance, supporting both technical excellence and regulatory compliance.