IEC 62610-6:2020

Overview

IEC 62610-6:2020 specifies measurement methods and performance indicators for air recirculation and bypass in indoor cabinets built to IEC 60297 and IEC 60917 series dimensions. The standard defines the recirculation ratio (RC) and bypass ratio (BP) as indicators of airflow quality in forced-air-cooled cabinets that host subrack and/or chassis-based equipment. It provides definitions, formulae and temperature measurement procedures needed to quantify how much exhaust air is re-ingested by equipment (recirculation) and how much conditioned supply air bypasses the equipment (bypass).

Keywords: IEC 62610-6, recirculation ratio, bypass ratio, thermal management, forced air cooling, IEC 60297, IEC 60917, cabinet airflow.

Key topics and technical requirements

• Definitions and scope
  • Formal definitions of recirculation and bypass flow rates applicable to indoor cabinets.
• Recirculation levels
  • Classification of recirculation severity (performance levels) to assess cooling effectiveness.
• Formulas for calculation
  • Prescribed formulae for:
    • RCs - recirculation ratio of a forced-air-cooled subrack/chassis,
    • RCr - recirculation ratio of the entire cabinet, and
    • BPr - bypass rate of the entire cabinet.
• Measurement methods
  • Temperature measurement locations and procedures for intake and exhaust air of subracks, subrack groups and entire cabinets.
  • Test guidance for empty cabinets and for using dummy thermal loads (DTL) to emulate installed equipment (see Annex A).
• Test and evaluation
  • Requirements for environmental conditions, measurement points and evaluation methods to ensure repeatable, comparable recirculation and bypass results.

Practical applications and users

IEC 62610-6 is intended to help:

• Cabinet suppliers - measure and classify cabinet airflow performance (recirculation and bypass) for product specifications and quality control.
• Equipment integrators and designers - select cabinet configurations and cooling strategies that meet thermal-spec objectives and avoid overheating of subracks and chassis-based equipment.
• Data center and telecom engineers / HVAC designers - assess room-level interactions between air conditioning and cabinet cooling effectiveness.
• Test laboratories - perform standardized measurements using specified temperature probe locations and dummy loads.

Benefits include improved thermal reliability, predictable intake temperatures, and better energy efficiency by reducing unnecessary bypass and recirculation.

Related standards

• IEC 60297 and IEC 60917 series (cabinet and subrack mechanical dimensions)
• IEC 62610 series (other parts addressing forced-air cooling and thermal management), including IEC 62610-2 which addresses ideal airflow for forced-air cooled cabinets

Using IEC 62610-6 supports consistent, repeatable evaluation of cabinet airflow performance and helps stakeholders specify, test and validate thermal management in rack-mounted systems.