64 DETECTION OF GEAR RATIO AND CURRENT CONSUMPTION USING .

INTERNATIONALOF MECHANICALENGINEERINGInternationalJournal of JOURNALMechanical Engineeringand Technology(IJMET), ISSN AND0976 –6340(Print), ISSN 0976 – 6359(Online)Volume 3, Issue(IJMET)2, May-August (2012), IAEMETECHNOLOGYISSN 0976 – 6340 (Print)ISSN 0976 – 6359 (Online)Volume 3, Issue 2, May-August (2012), pp. 643-652 IAEME: www.iaeme.com/ijmet.htmlJournal Impact Factor (2012): 3.8071 (Calculated by GISI)www.jifactor.comIJMET IAEMEDETECTION OF GEAR RATIO AND CURRENT CONSUMPTION USINGMOTOR CURRENT SIGNATURE ANALYSISG DIWAKAR, Assoc professorMechanical engineering Department, PVP Siddhartha Institute of Technology,Vijayawada, Andhra Pradesh, Indiagarikapadi@yahoo.co.inM.V.H.Sathish Kumar Assoc professorMechanical engineering Department, PVP Siddhartha Institute of Technology,Vijayawada, Andhra Pradesh, Indiasathish movva@rediffmail.comDr.M R S SatyanarayanaVice Principal, Gitam University.Visakhapatnam, Andhra Pradesh, India.mrsmunukurthi@rediffmail.com.ABSTRACTTo achieve reliable and cost effective diagnosis, Motor current signature analysis is used toinvestigate the use of an induction motor as a transducer to indicate the faults in multistage gearbox viaanalyzing supply parameters such as phase current and instantaneous power. In gearboxes, loadfluctuations on the gearbox and gear defects are two major sources of vibration. Further at times,measurement of vibration in the gearbox is not easy because of the inaccessibility in mounting thevibration transducers. This analysis system can be used for measuring the characteristics for a perfectlyworking gearbox and use the data as a standard for measuring faults and defects in other gearboxes. Theobjective of this paper is to design and fabricate a gearbox motor current analysis system at different gearoperations on no load. No load conditions on the gearbox are tested for current signatures during differentgear operations. Also found the minimum power required to run on different gears and gear ratio. Themotor current analysis system can be used further to specify mainly faults in the gear, misalignment ofmeshed gears, loss of contact of the gears and bearing wear.1. INTRODUCTIONThe monitoring of a gearbox condition is a vital activity because of its importance inpower transmission in any industry. Therefore, to improve upon the monitoring techniques for finding thegear ratios in the gearbox and the current passing through the motor running the gearbox has been aconstant endeavor for improvement in these monitoring techniques. Techniques such as wear and debrisanalysis, vibration monitoring and acoustic emissions require accessibility to the gearbox either to collect643

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEMEsamples or to mount the transducers on or near the gearbox. But dusty environment, background noise,structural vibration etc. may hamper the quality and efficiency of these techniques. Hence, there is a needto monitor the gearbox away from its actual location, which can be achieved through Motor currentsignature analysis (MCSA) which has already been successfully applied to condition monitoring ofinduction motor for finding friction in bearings.[15] Personnel at Oak Ridge National Laboratory havefound that MCSA can also provide information about system vibrations and imbalances similar to theinformation provided by an accelerometer. As a result, MCSA techniques for monitoring the status of theequipment, such as pumps, compressors and gear drives driven by induction motors have been developedand used in dedicated monitoring systems. Also we can find in particular, if there are some faults in a gearbox drive, the main current signal will be modulated by additional waveforms induced by faultcomponents. [11]2. LITERATURE REVIEWGear box fault detection can mainly be done through vibration and motor current analysis. The formermethod uses the fact that Vibration Faults, when they begin to occur, alter the frequency spectrum of thegear vibration. Particular faults are identified by recognizing the growth of distinctive sideband patterns inthe spectrum. [1] The spectrum is recorded with the help of oscilloscope when the accelerometer is placedon the gearbox to be tested. The noise signature is affected by the background noise and the noisefield.[5]These limitations of prevalent techniques bolster the justification of using the motor currentsignature analysis (MCSA), which has already been used for condition monitoring of motor operatedvalves of nuclear plants [3], [4], worm gears [5], induction motor and bearings [6]–[11],and multistagegearbox [12], [13].The basis of fault detection is the difference in normalized current RMS values of both healthy and faultybearings. Broken rotor and eccentricity in the rotor and stator of an induction motor result in side bands ofelectric supply line frequency. Prior knowledge of spatial position of fault and the load torque withrespect to the rotor is necessary as the effects of load torque and faulty conditions are difficult to separate.Motor current signals can be obtained from the outputs of current transducers which are placed nonintrusively on one of the power leads. The resulting raw current signals are acquired by computers afterthey go through conditioning circuits and data interfaces. [14] These signals are then studied to determinefaults occurring in gearbox. Although numerous techniques are available of non intrusive type of testingfor fault detection, they have their own limitations. The present work thus aims to develop and propose amethod which is simpler to find speed of gearbox and fault in gearbox by finding power consumption ofmotor.3. EXPERIMENTAL SETUPThe experimental set up consists of a four pole three-phase induction motor coupled to a 4-speedautomotive gearbox. The coupling used is a shaft coupling. The input speed of the gearbox is themechanical speed of the induction motor. Induction motor is also connected to dimmer stat which controlsthe power to the motor by varying the input voltage which further drives the gearbox output shaft. Thenthere are current probes to measure the current response. Voltmeter and an Ammeter are used here formeasuring voltage and current readings.644

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEMEFig 1: Schematic diagram of Experimental setup.Description of various parts of the experimental setup is as follows:1.3 Phase Induction MotorThe motor has the following Configuration,MakeRated PowerRated SpeedFrequencyVoltageCurrent::::::Siemens1.48 kW.1440rpm50 Hz.440 V.0.5 A.2. Dimmer StatFig 2: DIMMER STAT used in the experiment645

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEMEThe DIMMER STAT used in the experiment has the following configurationType: 15D-3PMax KVA: 12.211Connection for Max output voltage to input equalInput at A1 A2 A3 V3 -50/60HZ415Output at E1 E2 E30-415VoltsConnection for Max output voltage higher than inputInput at B1 B2 B3415Output at E1 E2 E30-470V-3 -50/60HZVoltsOutput current 15amp per line3: GearboxA gearbox or transmission provides speed and torque conversions from a rotating power source to anotherdevice using gear ratios. The most common use is in automobiles where the transmission adapts theoutput of the internal combustion engine to the drive wheels. Such engines need to operate at a relativelyhigh rotational speed, which is inappropriate for starting, stopping, and slower travel. The transmissionreduces the higher engine speed to the slower wheel speed, increasing torque in the process.The gearbox used in the experiment is a 4-speed manual transmission automotive gearbox.Fig.3: 4-speed manual transmission gearbox4: shaft couplingShaft coupling is a coupling used to connect two rotating shafts of different diameters. The shaft isconnected to one end at the motor and the other end at gearbox.646

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEMEFig.3: shaft coupled to motor and gearbox5. FABRICATIONThe setup was placed on a Cast iron rectangular block. Induction motor and gearbox were connected onthe rectangular block. Channel was used for placing the 3-phase induction motor so that the motor and thegearbox are properly aligned with each other. Both the motor and gearbox are coupled by a shaft so thatthe gearbox is fixed completely and does not vibrate during high rotational speeds.Fig 4: the Final fabricated set-up.6. OBSERVATIONSThe basic aim of the experimentation was to design the arrangement in order to predict the gearratio of the gearbox and to get the motor current signature of the input motor. For this the arrangementwas done and the motor was made to run in various RPM which was controlled by the dimmer stat. Themotor was run on four different speeds between 1300 to1440 RPM respectively and the speed of thedriven shaft was measured using a Tachometer. 4 such readings were taken each for the 4 different gears.The results of the run are given in the table below:1st gear amp)Motorspeed(rpm)Gearboxspeed(rpm)Gear arratio15.75Dimmerpower %26283031

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEME2ndgear d(rpm)GearratioOverallGearratio9.91Dimmerpower %232527293rdgear readingS.NO1234OverallGearratio5.85Dimmerpower %232426294th gear readingsS.NO1234OverallGearratio3.95Dimmerpower %27293234Reverse gear Dimmerpower 031480.6140295.214.723241600.54142296.714.7034So the overall gear ratio for the 4 speed manual transmission gearbox is: 1st gear: 15.75 2nd gear: 9.91 3rd gear: 5.85 4th gear: 3.95 Reverse gear: 14.77From the data collected the current flow to the motor with the changing speed of motor, graphs are plotted withcurrent vs. RPM and voltage vs. RPM of the driving shaft. With current & voltage on Y-axis and speed of the motoron X-axis 4 different graphs are plotted.648

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEMEGraphs drawn for current vs.rpm at different speeds:111st gear ratio: 15.750.60.60.40.40.20.200140014101420 1430RPM14401450138013rd gear ratio: 5.851420RPM14400.60.60.40.40.20.20013501350 1370 1390 1410 1430 1450RPM10.84th gear ratio: 3.950.8ampamp140010.8amp2nd gear ratio: 9.910.8ampamp0.8Reverse gear ratio:14.770.60.40.201320 1340 1360 1380 1400 1420 1440RPM64913701390 1410RPM14301450

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), IAEMEGraphs drawn for voltage vs.rpm at different speed1501501st gear ratio: 15.752nd gear 101420 1430RPM144014501380140014201440RPM1501804th gear ratio: 3.953rd gear ratio: 5.85140voltsvolts160130120110140120135013701390 1410RPM14301450135013701390 1410RPM14301450190Reverse gear ratio:14.77volts1701501301101320 1340 1360 1380 1400 1420 1440RPMGraph drawn for I vs. no. of gears at 1400 5%Graphs drawn for V vs. no. of gears at 1400 ears650123Gears456