Explosive atmospheres - Part 31: Equipment dust ignition protection by enclosure "t"

IEC 60079-31:2008 is applicable to electrical equipment protected by enclosure and surface temperature limitation for use in explosive dust atmospheres. It specifies requirements for design, construction and testing of electrical equipment. This standard supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of this standard shall take precedence. This first edition of IEC 60079-31 has been developed from the first edition of IEC 61241-1 (2004) which it now cancels and supersedes. The significant changes with respect to the previous edition are: - Title changed to Equipment dust ignition protection by enclosure 't' - Combination and rationalisation of practice A and B into a single practice, and some constructional requirements that may have applied to only one practice now apply to all enclosures - Introduction of three levels of protection, 'ta', 'tb' and 'tc' - Defined test voltage ranges and overload conditions for thermal tests - Introduction of a pressure test prior to the IP test - Restrictions on power and voltage levels for level of protection 'ta' - Introduction of a variant of the IP6X test for level of protection 'ta' - Compulsory dust layer thermal test for protection level 'ta' by surrounding the enclosure with dust to a depth of at least 500 mm on all available surfaces. The contents of the corrigendum of March 2009 have been included in this copy.