1 Scope
This part of GB 12476 is applicable to electrical apparatus protected by enclosures and surface temperature limitation for use in areas where combustible 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 part supplements the general requirements in GB 12476.1.
Note: GB 12476.2 gives guidance on the selection and installation of the apparatus. Apparatus within the scope of this part may also be subjected to additional requirements in other standards – for example, GB 3836.1.
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 "dust-tight" or "dust-protected" enclosures.
The application of electrical apparatus in atmospheres which may contain explosive gas as well as combustible dust, whether simultaneously or separately, requires additional protective measures.
Where the apparatus must meet other environmental conditions, for example, protection against ingress of water and resistance to corrosion, additional methods of protection may be necessary. The method used should not adversely affect the integrity of the enclosure.
This part does not apply to dusts of explosives which do not require atmospheric oxygen for combustion, or to pyrophoric substances.
This part is not applicable to electrical apparatus intended for use in underground parts of mines as well as those parts of surface installations of such mines endangered by firedamp and/or combustible dust.
This part does not take account of any risk due to an emission of flammable or toxic gas from the dust.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 4208-2008 Degrees of protection provided by enclosure(IP code) (IEC 60529: 2001, IDT)
IEC 61241-0: 2013 Electrical apparatus for use in the presence of combustible dust Part 0: General requirements)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61241-0, as well as the following definitions, apply.
3.1
dust ignition protection type “tD”
all relevant measures applied to electrical apparatus protected by an enclosure to avoid ignition of a dust layer or cloud
Foreword I
Introduction III
1 Scope
2 Normative references
3 Terms and definitions
4 Construction
5 Practice A and practice B
6 Supplementary requirements for electrical apparatus protected by enclosures for practice A for use in zones 20, 21 and
7 Supplementary requirements for electrical apparatus protected by enclosures for practice B for use in zone 20 or
8 Verification and tests
9 Marking
Bibliography
