IEC 62391-2:2025

Overview

IEC 62391-2:2025 is an internationally recognized standard issued by the International Electrotechnical Commission (IEC), focusing on fixed electric double-layer capacitors (EDLCs) specifically designed for power applications. This standard defines the sectional specification for EDLCs that deliver discharge currents ranging from milliamperes (mA) to amperes (A). These capacitors are critical for applications demanding relatively high capacitance and low internal resistance, aligned with Class 3 and Class 5 measurement classifications as per IEC 62391-1:2022.

This second edition introduces significant technical updates, including a complete restructuring to comply with ISO/IEC Directives Part 2, new technical categories for test methods, and revised references and figures.

Key Topics

• Preferred Ratings and Characteristics
  The standard defines preferred nominal capacitance values, tolerances, rated voltage, temperature, and internal resistance specific to power EDLCs. These parameters ensure optimum performance and reliability for high-demand applications.

• Test and Measurement Procedures
  IEC 62391-2:2025 specifies comprehensive test methods including visual inspections, electrical tests (capacitance, internal resistance, leakage current), robustness, solderability, vibration, temperature variations, endurance, and more. These procedures ensure conformance to stringent quality and performance requirements.

• Quality Assessment
  The document outlines procedures for quality assessment throughout the manufacturing lifecycle, including primary manufacture evaluation, testing structurally similar components, qualification approvals, and lot-by-lot inspections. This helps maintain consistent capacitor performance and reliability.

• Power Density Calculation
  Annex A details the calculation methods for power density per mass and volume, providing a standardized approach to quantify capacitor energy performance - a key consideration in power applications.

Applications

Fixed electric double-layer capacitors covered by IEC 62391-2:2025 are widely utilized in electric and electronic equipment requiring rapid energy discharge and high power density. Typical applications include:

• Energy storage systems in power electronics
• Hybrid and electric vehicles for power buffering
• Backup power supplies and uninterruptible power systems (UPS)
• Industrial power equipment and renewable energy systems
• Consumer electronics demanding high current pulses

By adhering to this standard, manufacturers and users ensure that capacitors meet reliable operational criteria, safety, and durability under demanding electrical and environmental conditions.

Related Standards

• IEC 62391-1:2022 – This foundational standard classifies measurement methods and performance requirements for electric double-layer capacitors, serving as a basis for Part 2 specifications.
• ISO/IEC Directives, Part 2 – Provides guidelines on the structure and drafting of IEC standards, which IEC 62391-2:2025 incorporates for clarity and consistency.
• IEC 62638 – Covers hybrid capacitors which might be relevant depending on the application requirements.

Practical Value

Implementing IEC 62391-2:2025 helps organizations achieve:

• Enhanced Component Reliability through rigorous testing aligned with recognized global standards.
• Optimized Performance Metrics ensuring capacitors meet high capacitance and low internal resistance for power applications.
• Standardized Quality Assurance facilitating supplier audits, product certifications, and compliance verification workflows.
• Improved Design Efficiency by providing clear guidance on ratings, testing, and marking that aid in component selection and system integration.

Organizations engaged in manufacturing, testing, or deploying fixed electric double-layer capacitors for power applications will benefit from adherence to this standard to meet industry performance benchmarks and regulatory requirements.

Keywords: IEC 62391-2:2025, electric double-layer capacitors, EDLC, power capacitors, capacitor standards, IEC capacitors, capacitor testing, power density, electric capacitor quality assessment, electric and electronic equipment capacitors