ELECTRIC MOTORS IN EXPLOSIVE ATMOSPHERES: PRACTICAL GUIDE FOR SELECTION

Abstract

ABSTRACT: The risk of explosion is extremely high in numerous industrial processes where flammable substances are involved. Due to the dramatic consequences, both personal and material, associated with these accidents, it is extremely important to maintain severe security measures in these industries. These security measurements are regulated by the “European directive 94/9/EC on equipment and protective systems intended for use in potentially explosive atmospheres”, also called ATEX Directive. This paper shows the appliance of this directive on electric motors employed in hazardous areas. Electrical equipment and specially the electric motors may cause an explosion by an excessive temperature raise or an electrical arc. To avoid these accidents several protections methods have been developed. This paper analyzes the protection methods for electric motors. As a main contribution, the basic criteria to choose the most suitable protection method are described. Finally, a medium voltage motor for a hydrogen compressor working in a hazardous area is included. Keywords: Induction motors, squirrel cage motors, hazardous areas, ATEX, protection modes, flameproof, increased safety, pressurised, non-sparking, dust ignition proof.