Flameproof Motors - Elec.ru

www.weg.net4.4.4. EncodersFor an accurate application control an encoder is typically used.Encoders are direct coupled to a motor shaft extension and fixed inthe external part of fan cover grid.the manufacturer considers S1 for duty type (continuous runningduty).S1- Continuous running dutyOperation at a constant load maintained for sufficient amount of timefor thermal equilibrium to be reached.Figure 4.05 - Encoder position4.4.5. Bearing insulationIn order to avoid current in the bearings, in variable speed driveapplications, special bearing arrangements have to be considered.The WEG solution in flameproof motors is to use insulated bearingsand internal shaft grounding rings. Motors intended to be used withVSD application must have the following features.Range Frame Standard OptionalBFGC4W22X250-280 Standard bearing315315-400450-500Non drive endinsulated bearingNon drive endinsulated bearingNon drive endinsulatedbearing + driveend endshieldgrounding ringNon drive endinsulated bearingNon drive endinsulated bearing + drive endendshield grounding ringNon drive endinsulated bearing + drive endendshield grounding ringNon drive endinsulated bearing + drive endendshield grounding ringDrive and non drive endinsulated bearings + driveand non drive end endshieldsgrounding ringsFigure 4.06 - Duty type S1S2- Short-time dutyOperation at a constant load during a standard time, less than thatrequired to reach thermal equilibrium. Followed by a rest period longenough until winding has cooled down to the ambient temperature.Operating times of 10, 30, 60 or 90 minutes are recommended.Table 4.09 - Bearings protection for VSD driven motors4.4.6. Operating speedFor VSD operation motors, the speed ranges must be confirmed.Depending on the operation speed, restriction can arise frombearings/sleeve bearings maximum peripheral speed, from rotationalparts or due to rotor natural frequencies.For more information please refer to paragraph 6.4.5. Duty CyclesFigure 4.07 - Duty type S2The table 4.10 shows the overload values, considering a heatingtime constant of 20 min.The different duty types are defined according to IEC 60034-1.Duty types are the different degrees of load regularity at which themotor is submitted. It is customer responsibility to choose the duty.The duty type shall be designated by the appropriate abbreviation,written after the load value. When customer does not declare a duty,42 | Flameproof Motors