Overview
IEC TR 60890:2014 provides a standardized method for verifying the temperature rise of low-voltage switchgear and controlgear assemblies by calculation. Issued by the International Electrotechnical Commission (IEC), this technical report addresses the need for effective and reliable temperature-rise assessment in low-voltage electrical enclosures, ensuring operational safety and compliance in various electrical installations. It applies to enclosed assemblies or partitioned assembly sections without forced ventilation and guides users on calculating temperature rise based on enclosure design, installation type, and internal power losses. The standard aligns with IEC 61439-1:2011 and replaces the previous edition, introducing updated formulas, revised annexes, and enhanced editorial clarity.
Key Topics
- Scope and Applicability
- Method suitable for enclosed low-voltage switchgear and controlgear assemblies without forced ventilation.
- Not applicable when verification methods per IEC 61439 series are already in place.
- Designed for enclosures commonly made from sheet steel, aluminum, cast iron, or insulating material.
- Focuses on determining air temperature rise inside the enclosure due to equipment power losses.
- Conditions for Application
- Requires known power loss data for all installed components.
- Assumes even distribution of power losses internally.
- No significant impediment to air circulation within the enclosure.
- Applicable for DC/AC assemblies with supply currents up to 3,150 A.
- Enclosure design must limit eddy-current and hysteresis losses.
- No more than three horizontal partitions allowed within the enclosure.
- Calculation Methodology
- Step-by-step approach for determining effective cooling surface, power losses, and internal temperature rise.
- Considers enclosure dimensions, partitioning, type of installation, and ventilation openings.
- Utilizes specific factors and formulas for different enclosure configurations, referencing updates from Annex B and editorial enhancements.
- Evaluation of Results
- Ensures that equipment remains within safe operating temperature limits.
- Recommends recalculation if design parameters result in excessive temperature rise.
Applications
The method outlined in IEC TR 60890:2014 offers practical value in several settings:
- Design Verification:
Facilitates the design and verification of temperature rise in low-voltage switchgear and controlgear assemblies before physical testing or installation.
- Safety and Compliance:
Supports manufacturers and electrical engineers in meeting global safety standards and preventing equipment overheating, a key factor for electrical safety and longevity.
- Installation Planning:
Assists in planning for installations across industrial, commercial, and infrastructure projects where forced ventilation in assemblies is not feasible or desired.
- Engineering Analysis:
Provides a standardized calculation framework for assessment and optimization in engineering studies, allowing reliable comparisons and documentation.
Related Standards
IEC TR 60890:2014 references and aligns with several key standards in the field of low-voltage assemblies:
- IEC 61439-1:2011
Low-voltage switchgear and controlgear assemblies - Part 1: General rules
The primary reference for general requirements and testing methods, integrated into the updated 2014 edition of IEC TR 60890.
- IEC 60364 (Series)
Low-voltage electrical installations
Frequently cited in contexts related to installation environments and conductor sizing.
- Annex B of IEC TR 60890
Offers detailed information on operating currents and power losses for conductors, permitting precise input data for the temperature-rise calculations.
Keywords:
IEC TR 60890:2014, temperature-rise verification, low-voltage switchgear, controlgear assemblies, calculation method, electrical enclosures, power loss, IEC 61439, electrical safety, assembly design verification, equipment overheating prevention.