SIST EN 61642:2001

Overview

EN 61642:1997 (CLC) provides guidance on the application of passive a.c. harmonic filters and shunt capacitors in industrial a.c. networks affected by harmonics. The standard focuses on measures for limiting harmonic distortion and performing power factor correction in industrial installations at both low and high voltages. Its scope covers harmonic orders greater than 1 and up to and including the 25th order.

Key topics and requirements

The standard addresses practical guidance and considerations for the selection and use of passive equipment to improve power quality. Key technical topics include:

• Application of passive harmonic filters - guidance on when and how to use single-tuned, double-tuned or broadband passive filters as part of harmonic mitigation strategies.
• Use of shunt capacitors - recommendations for deploying capacitors for reactive power compensation and power factor correction in networks with harmonic content.
• Harmonic order applicability - measures are applicable for harmonic orders >1 up to and including the 25th harmonic.
• Coordination with network characteristics - considerations for matching filter and capacitor characteristics to the system impedance and operating voltages (low and high voltage networks).
• Operational and safety considerations - general guidance on installation, operation and monitoring to avoid unintended resonance and ensure reliable performance.
• Design and selection criteria - practical factors to consider when choosing passive components to achieve harmonic limitation and power factor targets.

Note: EN 61642 offers guidance rather than prescriptive technical limits; detailed design and verification should reference site-specific measurements and engineering practice.

Applications

EN 61642 is intended for industrial contexts where non-linear loads create harmonic distortion and reactive power issues. Typical applications include:

• Manufacturing plants with large motor drives, converters or rectifiers
• Process industries with extensive power electronic equipment
• Facilities aiming to reduce harmonic distortion and improve power factor to meet contractual or regulatory limits
• Retrofit projects where shunt capacitors or passive filters are added to existing networks

Using the guidance can reduce equipment overheating, nuisance tripping, transformer losses and improve energy efficiency.

Who should use this standard

• Electrical design and power quality engineers
• Plant electrical and maintenance managers
• Consultants and system integrators specifying harmonic mitigation solutions
• Manufacturers and suppliers of passive filters and shunt capacitors
• Utilities and network planners evaluating industrial network connections

Related standards

EN 61642 is commonly used alongside broader power quality and EMC standards (for example IEC/EN 61000 series) and standards covering voltage characteristics (e.g., EN 50160) when developing comprehensive harmonic mitigation and power factor correction strategies.