IEC 60940:2015

Overview

IEC 60940:2015 is an international standard published by the International Electrotechnical Commission (IEC). It provides comprehensive guidance on the application of capacitors, resistors, inductors, and complete filter units specifically designed for electromagnetic interference (EMI) suppression. The second edition of this standard updates and replaces the original 1988 version, incorporating minor but important revisions to reflect current technologies and practices.

The standard is a crucial resource for engineers, designers, and manufacturers working in fields where electromagnetic and radio-frequency interference (EMI/RFI) management is vital. It helps ensure that electrical and electronic equipment operate reliably by minimizing disturbances caused by unwanted electromagnetic emissions.

Key Topics

• Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI):

  • Definition of EMI as any electromagnetic emission causing undesirable responses or functional degradation.
  • Classification of RFI, focusing on conducted interference (150 kHz to 30 MHz) and radiated interference (30 MHz to 10 GHz).
  • Explanation of how EMI propagates via conduction through power lines and radiation through space.

• Suppression Components:

  • Types of suppression components used, including capacitors, resistors, inductors, and complete filter units.
  • Classification of capacitors into two-terminal capacitors, combination capacitors, lead-through capacitors, and resistor-capacitor combinations.
  • Use of inductors and filters for creating low impedance paths to divert unwanted interference currents.

• Ratings and Selection Criteria:

  • Guidelines for selecting voltage and current ratings appropriate for specific EMI suppression applications.
  • Environmental and climatic considerations affecting component performance.
  • Importance of insertion loss measurements in evaluating filter efficacy.

• Connection and Safety:

  • Best practices for mounting and connecting interference suppression components to optimize performance.
  • Safety requirements, including the use of Class X and Y capacitors for mains connection.
  • Addressing leakage currents and electrical shock hazard protections to align with safety standards such as IEC 60335-1.

• Compliance and Regulatory Limits:

  • Insight into national and international limits on allowable radio-frequency emissions from electrical equipment.
  • Reference to relevant EMC standards like CISPR 11 that define interference limits.
  • Necessity of interference suppression near the power supply input, especially for shielded equipment.

Applications

IEC 60940:2015 is essential for a wide range of industries where electromagnetic compatibility (EMC) is critical. Practical applications include:

• Consumer Electronics: Ensuring household appliances meet regulatory EMC requirements to prevent malfunction or interference with other devices.
• Industrial Machinery: Suppression of EMI generated by large motors, drives, and machinery to protect sensitive control systems and communication infrastructure.
• Telecommunications: Minimizing RFI that can degrade radio communications, data transmission, and broadcasting.
• Medical Equipment: Protecting medical devices from electromagnetic disturbances to maintain operational safety and accuracy.
• Automotive and Transportation: Reducing EMI effects from onboard electronics and power systems to enhance safety and system reliability.

By following IEC 60940 guidance, designers can improve product performance, meet legal compliance, and facilitate international market access through harmonized EMI suppression practices.

Related Standards

• IEC 60335-1: Safety requirements for household and similar electrical appliances covering general requirements, including electrical shock hazards.
• IEC 60384-14: Specifications for fixed capacitors used in electronic equipment for EMI suppression, complementing IEC 60940’s guidance on capacitor application.
• CISPR 11: Defines limits for radio-frequency electromagnetic disturbances from industrial, scientific, and medical equipment.
• EMC Directives and National Regulations: Various regional and international guidelines that enforce EMI/RFI emission limits for electrical apparatus.

Conclusion

IEC 60940:2015 offers detailed, practical guidance on applying key electronic components for the suppression of electromagnetic interference. This standard supports the design and implementation of effective EMI filters and suppression techniques crucial for compliance, safety, and optimal device performance. Engineers and manufacturers benefit from its classification, selection criteria, and safety practices, enabling the development of reliable and interference-resilient electrical and electronic systems worldwide.