IEC 60721-3-3:2019

Overview

IEC 60721-3-3:2019 is an international standard published by the International Electrotechnical Commission (IEC) that focuses on the classification of environmental conditions affecting products installed for stationary use at weatherprotected locations. This third edition, a technical revision of previous versions dating back to 1994, updated classifications of environmental parameters and their severities. The document helps manufacturers and engineers assess environmental influences on electrical and electronic equipment to ensure reliable performance in protected outdoor settings.

The standard specifically addresses groups of environmental parameters such as climatic conditions, mechanically active substances, and chemical agents, among others. It excludes conditions related to explosion hazards, fire extinction, ionizing radiation, and microclimates within products, thus focusing solely on direct environmental impacts.

Key Topics

• Stationary Use & Weatherprotected Locations
  Defines the scope of products mounted firmly or permanently placed at sites protected from direct meteorological effects.

• Classification of Environmental Parameters
  The standard categorizes environmental influences into several groups:

  • Climatic conditions (including newly revised climate classes and special conditions such as low air pressure)
  • Biological conditions
  • Chemically active substances, referencing ISO 9223 values
  • Mechanically active substances and mechanical conditions, fully aligned with IEC 60721-3-1

• Severities and Combined Effects
  The document classifies severities for each environmental parameter and emphasizes considering combinations of these parameters (e.g., temperature combined with humidity or mechanical vibrations) to evaluate their cumulative effects on product performance.

• Revision Highlights
  Major updates include integration and alignment with IEC 60721-3-1, introduction of new climate classes reflecting current climate types, addition of a low air pressure class, and removal of certain classes related to fire and other excluded factors.

• Informative Annexes

  • Annex A offers a climatogram illustrating the interdependence of air temperature, relative humidity, and absolute humidity.
  • Annex B defines seismic environments relevant for stationary products.

Applications

IEC 60721-3-3:2019 is primarily used in the design, testing, and evaluation of electrical and electronic equipment intended for installation at weatherprotected locations, such as:

• Telecommunications equipment housed in sheltered outdoor enclosures
• Industrial control panels fixed in semi-sheltered manufacturing environments
• Power distribution devices installed under protective covers or inside weatherproof cabinets
• Stationary sensors or measurement devices positioned outdoors but shielded from direct weather exposure

This classification aids manufacturers and stakeholders in specifying product environmental resistances, optimizing durability, and ensuring compliance with international standards to mitigate risks caused by environmental stresses. It supports product lifecycle planning by defining maximum short-term stresses, highlighting the importance of considering combined environmental factors during product development and testing.

Related Standards

• IEC 60721-3-0: Classification of environmental conditions - Introduction to classification of groups of environmental parameters and their severities
  Provides a foundational framework and terminology that supports IEC 60721-3-3.

• IEC 60721-3-1: Classification for stationary use in non-weatherprotected locations
  Complements this standard by addressing conditions for indoor or otherwise sheltered environments without direct weather protection.

• IEC 60721-2-1: Classification of climatic conditions
  Details updated climate types referenced for defining new climatic classes in IEC 60721-3-3.

• ISO 9223: Corrosion of metals and alloys - Classification of environmentally-induced corrosion
  Provides reference values for chemically active substances included in the environmental classification.

• IEC TR 62130 and IEC TR 62131-5: Technical reports on environmental conditions
  Offer further guidance on assessing long-term and total lifetime environmental stresses beyond the scope of short-term classifications.

Keywords: IEC 60721-3-3, environmental conditions classification, stationary use, weatherprotected locations, climatic conditions, mechanically active substances, chemically active substances, product reliability, environmental parameters severities, industrial standards, IEC standards, electrical equipment protection, environmental testing