bsen61241-1-20xxelectricalapparatusforuseinthepresenceofcombustibledust—part1protectionbyenclosures“t—”-文庫吧

【正文】 ................................................... 7 4 Construction .................................................................................................................. ... 7 5 Practice A and practice B ................................................................................................. 7 6 Supplementary requirements for electrical apparatus protected by enclosures for practice A for use in zones 20, 21 and 22 ......................................................................... 7 7 Supplementary requirements for electrical apparatus protected by enclosures for practice B for use in zone 20 or 21 ................................................................................... 8 Joints ...................................................................................................................... 8 Plain joints ................................................................................................. . 8 Spigotted joints............................................................................................ 8 Gasketed joints............................................................................................ 9 Operating rods, spindles or shafts ........................................................................... 9 General ....................................................................................................... 9 Running contact seals ................................................................................. 9 Power shafts ............................................................................................... 9 Operating rods........................................................................................... 10 Clearance of bolts ................................................................................................. 10 8 Verification and tests ...................................................................................................... 11 General ................................................................................................................. 11 Type tests ............................................................................................................. 11 Tests for dust exclusion by enclosures ...................................................... 11 Thermal tests ........................................................................................... . 13 9 Marking .......................................................................................................................... 13 Annex ZA (normative) Normative references to international publications with their corresponding European publications ............................................................................. 14 Annex ZZ (informative) Coverage of Essential Requirements of EC Directives ....................................15 B ibliography.......................................................................................................................... 16 Figure 1 – Plain joints ............................................................................................................. 8 Figure 2 – Spigotted joints ...................................................................................................... 8 Figure 3 – Gasketed joints ......................................................................................................9 Figure 4 – Power shafts for speeds of 100r/min or more ....................................................... 10 Figure 5 – Clearance of bolts ................................................................................................ 11 Table 1 – Plain joints .............................................................................................................. 8 Table 2 – Gasketed joints ....................................................................................................... 9 Table 3 – Power shafts for speeds of 100 r/min or more ....................................................... 10 Table 4 – Power shafts for speeds of less than 100 r/min ..................................................... 10 Page 4 EN 61241?1:2020 INTRODUCTION Many dusts which are generated, processed, handled and stored, are bustible. W hen ignited they can burn rapidly and with considerable explosive force if mixed with air in the appropriate proportions. It is often necessary to use electrical apparatus in locations where such bustible materials are present, and suitable precautions must therefore be taken to ensure that all such apparatus is adequately protected so as to reduce the likelihood of ignition of the external explosive atmosphere. In electrical apparatus, potential ignition sources include electrical arcs and sparks, hot surfaces, and frictional sparks. Areas where dusts, flyings and fibres in air occur in dangerous quantities are classified as hazardous and are divided into three zones according to the level of risk. Generally, electrical safety is ensured by the implementation of one of two considerations, . that electrical apparatus be located where reasonably practicable outside hazardous areas and that electrical apparatus be designed, installed and maintained in accordance with measures remended for the area in which the apparatus is located. Combustible dust can be ignited by electrical apparatus in several ways: ? by surfaces of the apparatus that are above the minimum ignition temperature of the dust concerned. The temperature at which a type of dust ignites is a function of the properties of the dust, whether the dust is in a cloud or layer, the thickness of the layer and the geometry of the heat source。 ? by arcing or sparking of electrical parts such as switches, conta