Explosion protection for electrical apparatus in the presence of combustible dusts

5 Explosion protection for electrical apparatus in the presence of combustible dusts 

Similar to installation rules, national standards for explosion protection in the presence of combustible dusts were established long before international standards. In Germany, VDE 0165/1991-092 (and this standard referring in parts to VDE 0170/0171 Teil 13/1986-11) defines requirements for electrical equipment operating in areas hazardous due to combustible dusts. 

At the present time, IEC 61241-3 combined with IEC 61241-1-1 and with IEC 61241-1-2 as international standards describe construction and testing of electrical apparatus for areas hazardous due to combustible dusts on the basis of a three-zone classification (zones 20,21 and 22). 

Following the IEC activities, CENELEC, Brussels, has drawn up standards covering construction, testing, selection, installation and maintenance of such apparatus based on a three-zone classification  

An additional standard is EN 50281-2-1/1998-09, overtaken as German Standard VDE 0170/0171 Teil 15-2-1/1999-11 (Test methods - Methods for determining the minimum ignition temperatures of dust). 

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