Danfoss MCD3000 Series Manual

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MCD3000 SeriesMG.15.A2.22 – VLT is a registered Danfoss trademar 37Design GuideApplication TypicalStart CurrentGeneral & WaterAgitator 4.0 x FLCCentrifugal Pump 3.5 x FLCCompressor (Screw, unloaded) 3.0 x FLCCompressor (Reciprocating, unloaded) 4.0 x FLCConveyor 4.0 x FLCFan (damped) 3.5 x FLCFan (undamped) 4.5 x FLCMixer 4.5 x FLCPositive Displacement Pump 4.0 x FLCSubmersible Pump 3.0 x FLCMetals & MiningBelt Conveyor 4.5 x FLCDust Collector 3.5 x FLCGrinder 3.0 x FLCHammer Mill 4.5 x FLCRock Crusher 4.0 x FLCRoller Conveyor 3.5 x FLCRoller Mill 4.5 x FLCTumbler 4.0 x FLCWire Draw Machine 5.0 x FLCFood ProcessingBottle Washer 3.0 x FLCCentrifuge 4.0 x FLCDryer 4.5 x FLCMill 4.5 x FLCPalletiser 4.5 x FLCSeparator 4.5 x FLCSlicer 3.0 x FLCPulp and PaperDryer 4.5 x FLCRe-pulper 4.5 x FLCShredder 4.5 x FLCPetrochemicalBall Mill 4.5 x FLCCentrifuge 4.0 x FLCExtruder 5.0 x FLCScrew Conveyor 4.0 x FLCTransport & Machine ToolBall Mill 4.5 x FLCGrinder 3.5 x FLCMaterial Conveyor 4.0 x FLCPalletiser 4.5 x FLCPress 3.5 x FLCRoller Mill 4.5 x FLCRotary Table 4.0 x FLCLumber & Wood productsBandsaw 4.5 x FLCChipper 4.5 x FLCCircular Saw 3.5 x FLCDebarker 3.5 x FLCEdger 3.5 x FLCHydraulic Power Pack 3.5 x FLCPlaner 3.5 x FLCSander 4.0 x FLCATTENTIONThe above start current requirements aretypical and appropriate in most circumstances.However, start torque requirements and performanceof motors and machines does vary. For greateraccuracy use the advanced model selectionprocedure.ATTENTIONFor applications that operate outside thestandard MCD3000 ratings of 10 starts perhour, 50% duty cycle, 40o C (104o F), <1000 metres(3280 ft) consult your local supplier.AAAAddddvvvvaaaannnncccceeeedddd mmmmooooddddeeeellll seseseselllleeeeccccttttiiiioooonnnn pppprrrrococococeeeedddduuuurererereThis method uses data on the motor and load todetermine the required start current and assumesoperation within the standard MCD3000 ratings of 10starts per hour, 50% duty cycle, 40o C (104o F), <1000metres (3280 ft).Advanced model selection should be used wheretypical figures listed in the standard model selectionprocedure are not considered certain enough.Advanced model selection is also recommended forhigh inertia applications and installations involving largemotors where motor start performance can varywidely.1. Calculate the required starting torque as apercentage of motor Full Load Torque (FLT).Generally machine suppliers will be able to providedata regarding the start torque requirements oftheir machinery. Where this data is not providedas a percentage of motor FLT it will need to beconverted.A motor's full load torque can be calculated asfollows2. Calculate the minimum start current required bythe motor to produce the required torque ascalculated above.IST = LRC x TSTLRTI ST = Minimum required start currentLRC = Motor Locked Rotor CurrentLRT = Motor Locked Rotor Torque