【正文】 t — Part 1: Protection by enclosures “tD” The European Standard EN 612411:2020 has the status of a British Standard ICS Amd. No. Date Comments 15758 Corrigendum No. 1 25 November 2020 Revision of supersession details 16958 Corrigendum No. 2 28 February 2020 Revision of EN foreword and supersession details in national foreword, and addition of Annex ZZ BS EN 612411:2020 National foreword This British Standard was published by BSI. It is the UK implementation of EN 612411:2020, incorporating corrigendum Decem ber 2020. It should be read in conjunction with BS EN 612410. It is identical with IEC 612411:2020. Together with BS EN 612410, it supersedes BS EN 5028111:1999 which will be withdrawn on 1 October 2020. It partially supersedes BS 64671:1985 and BS 64672:1988 which are withdrawn. The UK participation in its preparation was entrusted by Technical Committee GEL/31, Electrical apparatus for explosive atmospheres, to Submittee GEL/31/20, Apparatus for use in the presence of bustible dust. A list of anizations represented on this submittee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 13 Janu ary 2020 169。ISCHE NORM June 2020 ICS English version Electrical apparatus for use in the presence of bustible dust Part 1: Protection by enclosures tD (IEC 612411:2020) Mat233。res bustibles Partie 1: Protection par enveloppes tD (CEI 612411:2020) Elektrische Betriebsmittel zur Verwendung in Bereichen mit brennbarem Staub Teil 1: Schutz durch Geh228。i sches Komitee f252。 ? by discharge of an accumulated electrostatic charge。 ? any other ignition sources are avoided. Compliance with this part of IEC 61241 will only provide the required level of safety if the electrical apparatus is operated within its rating and is installed and maintained according to the relevant codes of practice or requirements, for example in respect of protection against overcurrents, internal shortcircuits, and other electrical faults. In particular, it is essential that the severity and duration of an internal or external fault be limited to values that can be sustained by the electrical apparatus without damage. Page 5 EN 61241?1:2020 Several techniques are available for the explosion protection of electrical apparatus in hazardous areas. This standard describes the safety features of these types of explosion protection techniques and specifies the installation procedures to be adopted. It is most important that the correct selection and installation procedures be followed to ensure the safe use of electrical apparatus in hazardous areas. Two different types of practice, A and B, are specified in this standard and are intended to provide an equivalent level of protection. Both of these practices are in mon use and the requirements of each should be followed without mixing either the apparatus requirements and selection/installation requirements of the two practices. They adopt different methodology with the primary differences being: Practice A Practice B W ritten principally as performancebased requirements W ritten principally as prescriptivebased requirements Maximum surface temperature is determined with 5 mm layer of dust and installation rules require 75 K margin between the surface temperature and ignition temperature of the particular dust Maximum surface temperature is determined with 12,5 mm layer of dust and installation rules require 25 K margin between the surface temperature and ignition temperature of the particular dust Method of determining dust ingress is according to IEC 60529 – IP Code Method of determining dust ingress is in accordance with the heat cycling test Page 6 EN 61241?1:2020 ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST – Part 1: Protection by enclosures “tD” 1 Scope This part of IEC 61241 is applicable to electrical apparatus protected by enclosures and surface temperature limitation for use in areas where bustible dust may be present in quantities which could lead to a fire or explosion hazard. It specifies requirements for design, construction and testing of electrical apparatus. This standard supplements the general requirements in IEC 612410. NOTE IEC 6124114 gives guidance on the selection and installation of the apparatus. Apparatus within the scope of this standard may also be subjected to additional requirements in other standards – for example, IEC 600790. The ignition protection is based on the limitation of the maximum surface temperature of the enclosure and on other surfaces which could be in contact with dust and on the restriction of dust ingress into the enclosure by the use of dusttight or dustprotected enclosures. The application of electrical apparatus in atmospheres which may contain explosive gas as well as bustible dust, whether simultaneously or separately, requires additional protective measures. W here the apparatus has to meet other environmental conditions, for examp