Explosion-protected electric motors - Hew-hf.de

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Gas explosion protection 1/4 Three-phase A.C. motors Ignition temperature - Temperature class Numerous factors, such as size, shape, type and quality of the surface, influence the ignition temperature. IEC; CENELEC and other standards authorities have agreed on a process set out in IEC 60079-4 for determining the ignition temperature which comes very close to the lowest, practically possible value. It allocates gasses and vapours to temperature classes. These temperature classes are used to construct electrical equipment and other technological installations to rule out the possibility of a surface temperature ignition. The standards set out the permissible exceedances and compulsory lower deviations from these control values. The normal version of the motors is equivalent to the highest group IIC and the temperature class T4 which include all lower groups and temperature classes. Motors in temperature class T4 deliver the output as standard motors without explosion protection of the same construction size. On request, motors can also be supplied in temperature classes T5 and T6 in which case the permitted housing temperature has to be taken into account and the rated power adjusted as necessary. Temperature class Ignition temperature range Permitted surface temperature Permitted tempera- of the mixture of the electrical equipment ture increase T1 > + 450 °C + 400 °C + 410°C T2 > + 300...< + 450°C + 300 °C + 260°C T3 > + 200...< + 300°C + 200 °C + 160°C T4 > + 135...< + 200°C + 135 °C + 95 °C T5 > + 100...< + 135°C + 100 °C + 60 °C T6 > + 85... < + 100°C + 85 °C + 45 °C Examples of the classification of gasses and vapours in temperature classes and explosion subgroups. T1 T2 T3 T4 T5 T6 IIA Methane Propane Benzine Acetaldehyde IIB Ethylene Diethyl ether IIC Hydrogen Acetylene Carbon disulphide Dust explosion protection Surface temperature - Protection class An essential characteristic of dust explosion protection is the IP protection class. The motor is subject to different requirements for dust-tightness depending on the ambient conditions. The limitation of the surface temperature of motors to a value which is below the ignition and smouldering temperature of the present dust is important to dust explosion protection. Location Existence of a explosive dusty atmosphere occasional rare or fleeting rare or fleeting Type of dust all types conductive non-conductive Zone 21 22 22 Equipment Device group II II II Device category 2D 2D 3D Protection class IP65 IP65 IP55 Temperature max. 135°C max. 135°C max. 135°C Housing temperature Certification EC type examination certificate for the testing centre EC type examination certificate for the testing centre EC declaration of conformity of the manufacturer HEW DEx series
Three-phase A.C. motors Permitted use of motors as per marking, depending on zone allocation Group Category Zone allocation Definition Certification obligation For combustible gasses, vapours and mist II 1G* 0 Zone 0 includes areas in which an explosive atmosphere which arises constantly, long-term or frequently due to a mixture of air and gasses, vapours or mist. Yes II 2G 1 Zone 1 includes areas in which an explosive atmosphere is expected to arise occasionaly due to gasses, vapours or mist. Yes II 3G 2 Zone 2 includes areas in which an explosive atmosphere is not expected to arise from gasses, mists or vapours but if it does arise, it is likely to be rare and for a short period of time. No For combustible dusts II 1D* 20 Zone 20 includes areas in which an explosive atmosphere caused by a dust/air mixture arises constantly, long-term or frequently. Yes II 2D 21 Zone 21 includes areas in which an explosive atmosphere is expected to arise occasionaly due to a dust/air mixture. Yes II 3D 22 Zone 22 includes areas in which an explosive atmosphere is not expected to arise from swirled up dust but if it does arise, it is likely to be rare and for a short period of time only. No *Not common for electric motors Maintenance of explosion protection Maintenance of explosion protection during operation: Electrical machine must be protected from overheating caused by overloads. The motor protection depends on both the operating mode and the use of the electrical machine. Explosion-protected electric motors are generally approved for operating mode S1, i.e. continuous operation. Other operating modes are only permitted if the motor temperature is monitored by reliable devices. Operating mode Motor protection S1 Motor protection switch as per EN 60034-1; EN 60079-14 Motor protection switch and temperature sensor in the winding as additional protection Just the temperature sensor in the winding as the main protection (only permitted for tested and approved motors and with approved control devices) S2, S3 Motor protection switch with switch-on time switch and/or temperature sensor in the winding as additional protection. Just the temperature sensor in the winding as the main protection (only permitted for tested and approved motors and with approved control devices) S4, S5, S6, S7, S8 Just the temperature sensor in the winding as the main protection (only permitted for tested and approved motors and with approved control devices) S9, S10 Just the temperature sensor in the winding as the main protection (only permitted for tested and approved motors and with approved control devices) Definition of operating modes as per EN 60034-1 HEW DEx series 1/5 1
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Page 7 and 8: Three-phase A.C. motors Overview of
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Page 36 and 37: No. of poles: 4 Nominal data at 400
Page 38 and 39: No. of poles: 8 Nominal data at 400
Page 40 and 41: No. of poles: 4-2 Nominal data at 4
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Three-phase A.C. motors HA HD I K L
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Dimension sheets Customized motors
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Three-phase A.C. motors Types DEx 6
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Types DEx 63 - 315 Special version:
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Explosion-protected electric motors - Hew-hf.de

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