Drives & Controls November/December 2023

n SAFETY collector. This highlights the importance of ensuring that such equipment – including protective systems such as isolation devices, safety devices such as overload protection devices, or components such as vent ducts – complies with Atex 114 Directive 2014/34/EU. By compelling constructors to carry out an ignition hazard analysis, evaluating the risk level of hot surfaces, flames and hot gasses, mechanically generated sparks and static electricity and so on, users can rest assured that the equipment they install is not a potential ignition source. Dust and gas In legislative terms, a distinction is made in terms of dust zoning and gas zoning, as well as underground (Group I) and aboveground (Group II) equipment. A notified body is responsible for approving electrical systems and for all aspects of the top level of protection. This Very High (1G or 1D) category ensures that no ignition source is present during normal operation, as well as in the event of malfunctions. At this point, the two Atex directives intertwine, with the level of protection required for operation in a previously specified zone now becoming apparent. So, for example, Zone 22, the lowest dust danger zone, will require 3D-level equipment, while 1D protection will be needed in Zone 20 (see table). Manufacturers are obliged to supply equipment with the correct markings and to provide clear information on any residual risks, safe use and any limits. Conforming equipment will clearly display Atex identification in the form of the hexagon symbol, followed by numbers stating the equipment group (for example, II for above ground) and the safety category (for example, 1 for Zone 20/0), plus the letter D or G to signify the type of explosive atmosphere. The next two sets of markings verify the dust group (combustible, conductive or non-conductive) and temperature class. n GAS DUST Zone Category Zone Category No explosion risk _ No Atex approval required No Atex approval required Less likely to occur (up to 10 hours per year) 2 Cat 3G 22 Cat 3D* Likely to occur (10 to 1000 hours per year) 1 Cat 2G 21 Cat 2D Highly likely to occur (Very frequent or continuous) 0 Cat 1G 20 Cat 1D A summary of the Atex directive zone and equipment categories * if the dust is conductive, all electrical components must be at least IP6X