Screen Protected Drip Proof Low Voltage Slipring …

1 Screen Protected Drip ProofLow Voltage Slipring induction MotorsRW TypeMotors for the Long Run!A REGAL-BELOIT COMPANY2 Construction :Frame and Endshields : Girder construction,rugged cast fabricated frame withinternally ribbed heavy cast endshields with centering spigotsand each secured by four substantial hightensile bolts for RW 78, 89 & 105 framesand eight bolts for RW 120 frames feet with ample thickness, are castintegrally to the frame and access is availablefor vertical drilling for dowelling pins to obtainpositive location and retention of alignmentwith driven machine under severe mechanicalshock, vibration or thermal expansion/contraction over a period. Two steel slingingeye bolts are screwed in stator frame.

2 Eachendshield is furnished with steel mesh coveredventilation openings except for force ventilatedmotors where only two openings for fixingthe ventilating ducts are and Rotor : Cold rolled (non-oriented)steel sheet is used for stator/rotor RW A symbol of versatilityThe type RW motors have been designed basically for heavy duty use with driven machine imposing overloadsand severe mechanical shocks and vibrations. These motors are equally suitable for smooth constant loads sincethe motors are also designed with high efficiency and power factor. Because of optimum utilisation of materials,with improved ventilation techniques the motors are 10 15% lighter in weight and yet more rugged because oftheir inherent special of high Pull Out Torque and inherent thermal margin kept for high slip operation these motors are ideallysuited for rerolling mills and cane cutter/cane crusher/care leveller/cane fiborizer applications pertaining to sugarindustries.

3 Because of high efficiency and power factor these mtors are also suitable for pump/fan :Protection & Cooling:IP23 ( Screen Protected Drip Proof ), IC01 Duties:The motors are basically rated for S1 (continuous duty) but can be adaptedto other duties such as S6, S7, S8 :Class F insulation (temperature rise limited to class B )Supply:3 phase, 415 volt 10%, 50 cycle 5% as standard. But other voltagesand frequencies are also catered for upto 660 volt unit and brushgear:Continuously ratedWinding and enclosure treatment:Tropicalisation treatment is provided as a standard :a)Horizontal footmounted B3 mounting as )Vertical flange mounting V1 construction available for frame sizesRW105, RW120, RW136, RW152 and are held by steel endplates.

4 Statorlaminations are keyed and retained in thestator frame through a key ring while themotor laminations are keyed to the shaft andsecured by steel : Stator is wound either withsuperenamelled wire as per IS 4800 part Vor with glass fibre lapped enamelled stripconductors, depending on size andapplication of for frame sizes upto RW89 are wouldwith round superenamelled copper wirewhereas for hither sizes bar wave windingsare provided. Rotor coil overhangs aresecured to an internal support ring, whileupper portion of the overhang is securedwith non magnetic : Class F to IS rise limited to class B limit inaccordance with IS 325. The insulatingmaterials, binders, fillers and impregnantsused for Class F insulation are the latest andproven to be fully compatible under thermalcycling are ageing, while thicknesses, layers,direct and creepage clearance supportingand securing elements etc.

5 Are maintainedat a level that only caters to the basic insulationlevels governed by the Voltage class of themotor but takes care of the mechanical stressescaused by the thermal cycling, short circuitand overloads, overspeeding, frequentstarting/ braking, forced vibrations, andshocks over the anticipated motor wound stators and rotors along with theirleads are first preheated for expulsion ofmoisture, cooled to prepolymerisationtemperature of the varnish, dipped inthermosetting varnish and baked the numberof dipping and baking cycles depending onthe type of environment and service System :The type RW motors are basically short corelength large diameter motors where coolingis inherently better. The inclusion of a powerfuland effective ventilation system furnishes alarge safety margin on temperature risethereby minimising duration for elevatedtemperature.

6 Additionally tunnel slots havebeen introduced in the large frame sizes fordirect cooling of stator conductors. The axialventilating holes and the tunnel slot systemalong with the blower capacity and battlesystem are matched for ensure effectivecooling to limit the winding temperature riseto safe stators and rotors are provided with alarge number of axial ventilating holes. Ahigh capacity radial discharge shaft mountedblower to robust steelplate construction (lightlyshrunkfit on motor shaft and secured by alocking plug and additionally, in case ofFig. 1 Wound StaperFig. 2 Coil Setting3vertical motors, secured by a locking ring)alongwith a fixed air guide provides apowerful suction through the motor . The fanblades are rivetted and spot welded andspecially designed for minimum windageloss.

7 Air is drawn from the non drive endradially and expelled similarly at the driveend, thereby ensuring that the cooling air isnot drawn from the immediate vicinity of thedriven machine to which the motor may becoupled in case of force ventilated motorsthe blower may be retained or dispensedwith. The blower is balanced separatelybefore mounting on the motor shaft and therotor and blower assembly are dynamicallybalanced again as an unit after :Rotors along with shaft mounted blower aredynamically balanced to limit vibration tovalue well within specified limits as perIS:12075. Lower vibration levels whenspecified by users, may also be , Bearing/Lubrication :nShaft : Large diameter shaft : For largeoutput the shaft is often mounted with 2bearings at non drive : Ball and rollerbearings are standard.

8 Cartridge typehousings exclude foreign matter and facilitateeasy maintenance Endplay arrangementsmay be provided if required. The motors areequally suitable for direct coupling throughflexible or solid couplings. The ball bearingat non driving end serves as the locatingbearing and caters to the axial thrustassociated with the most normal is case of high magnitude of thrustas in the case of vertically mounted motors,a special bearing arrangement such as duplexor angular contact, is incorporated. The sizeof bearing and shaft diameter provided inthe RW motors, will eliminate, in most cases,the need for a jackshaft (countershaft) drivewhen radial loads are exceptionally highand yet furnish an acceptable expectedbearing life.

9 The bearings are housed incartridges which are spigot located accuratelyinto the endshields, thereby furnishing thefacility of motor withdrawal from stator withoutdisturbing the nipples are provided and arefully accessible for grease replenishment whenthe motor is in service. Bearing cartridgesare machine groved to prevent ingress ofexcess grease into the sizes, as used in RW sizes of motorsare as follows :Frame 78N3176315RW 89N3206317RW 105N2246320RW 120N2246320RW 136N2246320RW 152 N326N224 RW 168L& 6224RW 168100NU3326332& RW 168112 Table 1 Slipring Unit, Brushes and Brushgear :Sliprings of hard wearing Copper Nickelalloy are mounted outside endshield atnondriving end. Collector is keyed to shaftand secured to witstand thermal cycling shockand vibration.

10 Carbon brushes are of a gradespecially selected to provide satisfactory wearlife. The brush holders are amply rated, thedesign of tension spring and associated leverspermit only a small change in brush pressurefor a large amount of brush wear, therebyminimising the frequency of tensionadjustment. All brushes are fully bedded onthe collector and run in before the motorsare despatched from the hinged sheet steel cover with threeswitchbolts and wingnuts is provided for rapidaccess to the brushgear and sliprings. Slipringsand brushgears are continuously rated formotors requiring speed regulations (withexternal rotor resistance) or with freqentstarting and chambers are having provision forventilation for cooler operation.