Use in Hazardous Environments • 217WAGO-I/O-SYSTEM 750ETHERNET TCP/IPThe following table represents the division and attributes of the materials tothe temperature classes and material groups in percent:Temperature classesT1 T2 T3 T4 T5 T6 Total*26.6 % 42.8 % 25.5 %94.9 % 4.9 % 0 % 0.2 % 432Explosion groupIIA IIB IIC Total*85.2 % 13.8 % 1.0 % 501* Number of classified materials7.3.5 Types of ignition protectionIgnition protection defines the special measures to be taken for electricalcomponents in order to prevent the ignition of surrounding explosiveatmospheres. For this reason a differentiation is made between the followingtypes of ignition protection:Identifi-cationCENELECstandardIECstandardExplanation ApplicationEEx o EN 50 015 IEC 79-6 Oil encapsulation Zone 1 + 2EEx p EN 50 016 IEC 79-2 OverpressureencapsulationZone 1 + 2EEx q EN 50 017 IEC 79-5 Sand encapsulation Zone 1 + 2EEx d EN 50 018 IEC 79-1 Pressure resistantencapsulationZone 1 + 2EEx e EN 50 019 IEC 79-7 Increased safety Zone 1 + 2EEx m EN 50 028 IEC 79-18 Cast encapsulation Zone 1 + 2EEx i EN 50 020 (unit)EN 50 039 (system)IEC 79-11 Intrinsic safety Zone 0 + 1 + 2EEx n EN 50 021 IEC 79-15 Electrical componentsfor zone 2 (see below)Zone 2Ignition protection “n" describes exclusively the use of explosion protectedelectrical components in zone 2. This zone encompasses areas whereexplosive atmospheres can only be expected to occur rarely or short-term. Itrepresents the transition between the area of zone 1, which requires anexplosion protection and safe area in which for instance welding is allowed atany time.Regulations covering these electrical components are being prepared on aworld-wide scale. The standard EN 50 021 allows electrical componentmanufacturers to obtain certificates from the corresponding authorities forinstance KEMA in the Netherlands or the PTB in Germany, certifying that thetested components meet the above mentioned standards draft.
