• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Vibration
 

Vibration

on

  • 1,707 views

Vibration analysis

Vibration analysis

Statistics

Views

Total Views
1,707
Views on SlideShare
1,707
Embed Views
0

Actions

Likes
14
Downloads
0
Comments
7

0 Embeds 0

No embeds

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel

17 of 7 previous next Post a comment

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
  • can i have a copy of this presentation for my reference. my email is darwin.libranda@gmail.com

    Thanks.
    Are you sure you want to
    Your message goes here
    Processing…
  • Please, can you send this presentation to my email. Really I need it. Thanks.
    Are you sure you want to
    Your message goes here
    Processing…
  • I read this ppt & impressed, could you please share this ppt for my reference, at ashokkv2004@gmail.com
    Are you sure you want to
    Your message goes here
    Processing…
  • Please, can you send this persentation to my email. Really I need it
    Are you sure you want to
    Your message goes here
    Processing…
  • I need this presentation. thanks,
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Vibration Vibration Presentation Transcript

    • Vibration Monitoring &Vibration Monitoring &AnalysisAnalysis
    • What is Vibration ?It is motion of mechanical parts back andforth from its position of rest /neutralposition.Vibration MonitoringVibration Monitoring
    • Vibration MonitoringVibration MonitoringWhat causesVibration ?Induced Force&Freedom for Movement
    • Vibration MonitoringVibration MonitoringHarmful Effects of Excess vibration• Increased load on BRGs: Reduced BRG Life• Higher Forces on Mountings:Foundation Loosening and Damage ofSupport Structure• Increased Stresses of M/c : Risk of fatiguecomponents
    • Vibration MonitoringVibration MonitoringHarmful Effects of Excess vibration• Decreased Equipment efficiency.• Reduced Output Quality.• Increased Maintenance Cost due tomore Component Failures andUnplanned Operations• Unsafe Operating Environment
    • Vibration MonitoringVibration MonitoringProblem Identifications• Unbalance• Misalignment• Mechanical Looseness• Antifriction / Sleeve Bearing Defects• Gear Defects
    • Vibration MonitoringVibration MonitoringProblem Identifications• Belt Defects• Impeller / Blade Defects• Bent Shaft• Electrical Problems• Resonance
    • Vibration MonitoringVibration MonitoringFundamental Realities• All Machines vibrate.• An increase in vibration level is a sign oftrouble & amplitude of Vibration depends onthe extent of defect in the machinerycomponents• Each trouble will create vibration with differentcharacteristics
    • VIBRATION FUNDAMENTALSTIMEPeriod(T)(1 complete cycle)Neutral PositionUpper LimitLower Limit90180270
    • Characteristics of VibrationCharacteristics of Vibration• Vibration characteristics areAmplitudeFrequency Hz or CPMPhase Angle or clock faceDisplacementVelocityAcceleration
    • Parameter SelectionParameter Selection• Frequency sensitivityDisplacement <600CPMVelocity 600-60,000CPMAcceleration >60,000CPMSpikeEnergy/SEEUltrasonic range
    • Frequency sensitivity
    • Vibration MonitoringVibration MonitoringDisplacementVelocityAcceleration
    • FFTFAST FOURIER TRANSFORM.• THE PROCESS OF TRANSFORMING TIMEDOMAIN SIGNAL TO FREQUENCYDOMAIN.• THE TIME DOMAIN SIGNAL MUSTFIRST BE SAMPLED ANDDIGITIZED.
    • Indian Institute For Production ManagementFFT SPECTRUM ANALYSISA method of viewing the vibration signal in a way that is more useful for analysisis to apply a Fast Fourier Transformation (FFT). In non-mathematical terms, thismeans that the signal is broken down into specific amplitudes at variouscomponent frequencies.
    • Time Domain - overall data is the sum ofall exciting and reacting forcesImbalanceRollingElementBearingCouplingchatterGearmeshTimeResultant ComplexWaveform
    • Spectrum AnalysisEnables precise evaluation ofmachinery condition and prediction
    • Fmax, LINES, AVERAGES.• Fmax REPRESENTS THE MAXIMUMFREQUENCY RANGE IN CPM OR HZ TO BESCANNED BY THE INSTRUMENT.• Fmax SHOULD NOT BE SET TOO HIGH SOTHAT THE RESOLUTION AND ACCURACYSUFFERS OR IT SHOULD NOT BE TOO LOWSO THAT WE MISS SOME IMPORTANT HIGHFREQUENCIES.
    • GUIDELINES FOR SETTING Fmax.• FOR MACHINES HAVING ANTI-FRICTION BEARINGS:- Fmax = 60 xRPM• FOR MACHINES HAVING SLEEVEBEARINGS:- Fmax = 20 x RPM• FOR GEAR BOXES:- Fmax = 3.25 x GMF
    • LINES OF RESOLUTION• THE RESOLUTION IS THE NUMBER OF LINESOR CELLS WHICH ARE USED TO CALCULATEAND DISPLAY THE FREQUENCY SPECTRUM.• THE BANDWIDTH CAN BE CALCULATED BYDIVIDING Fmax BY THE LINES OF RESOLUTION.• THE GREATER THE NUMBER OF LINES , THEBETTER IS THE ACCURACY.
    • FREQUENCYRESOLUTION Bandwidth =FF maxmaxtotal lines of resolutiontotal lines of resolutiontotal lines of resolutiontotal lines of resolutionAmplitudeFrequency FFmaxmaxlines or bins or cellslines or bins or cellsof resolutionof resolution
    • • FFT Calculation Time = Time to calculateFFT from Time Waveform [assuming nooverlap processing]Spectrum Data CollectionTimeFFT Calculation Time =FFT Calculation Time =(60) ( #FFT Lines) (#Averages)(60) ( #FFT Lines) (#Averages)Frequency SpanFrequency SpanWhere: #FFT = Number of FFT Lines or Bins in Spectrum# Averages = Number of AveragesFrequency Span measured in CPM
    • FFT SPECTRUM
    • OVERALLOVERALLVIBRATIONVIBRATIONTotal summation of all the vibration,with noregard to any particular frequency.
    • OVERALL VIBRATIONOverall vibration is the total vibration energy measuredwithin a frequency range. Measuring the “overall”vibration of a machine or component, a rotor in relationto a machine, or the structure of a machine, andcomparing the overall measurement to its normal value(norm) indicates the current health of the machine. Ahigher than normal overall vibration reading indicatesthat “something” is causing the machine or componentto vibrate more.
    • Overall VibrationOverall VibrationTotal summation of all the vibration,with noregard to any particular frequency.OA =OA=Overall level of Vibration Spectrum , Ai = Amplitude of each FFT linen = No. of FFT Lines of resolution , NBF= Noise Bandwidth for Window chosenA1 + A2 + ………………………+AnA1 + A2 + ………………………+An22 22 22NNBFBF
    • NOTE: Don’t be concerned about the math,the condition monitoring instrumentcalculates the value. What’s important toremember is when comparing overallvibration signals, it is imperative that bothsignals be measured on the same frequencyrange and with the same scale factors.
    • What is Phase?What is Phase?• The position of a vibrating part at a giveninstant with reference to a fixed point oranother vibrating part.• The part of a vibration cycle through whichone part or object has moved relative toanother part.The unit of phase is degree where onecomplete cycle of vibration is 360 degrees.
    • PhasePhase is a measurement, not a processingmethod. Phase measures the angulardifference between a known mark on a rotatingshaft and the shaft’s vibration signal. Thisrelationship provides valuable information onvibration amplitude levels,shaft orbit, and shaftposition and is very useful for balancing andanalysis purposes.
    • Vibration PhaseVibration Phase
    • AdditionalIllustration onPhase
    • PHASE AN ILLUSTRATIONPHASE AN ILLUSTRATION30 Micron10 degrees32 Micron10 degreesShaft centre line moves up and down in a planer fashion
    • PHASE AN ILLUSTRATIONPHASE AN ILLUSTRATION30 Micron10 degrees32 Micron190 degreesShaft center line moves up and down in a rocking fashion
    • MACHINE TRAIN MISALIGNMENTMACHINE TRAIN MISALIGNMENTNote: All phase readings corrected for pickup directionTURBINE G/B HP COMP LP COMPAXIAL PHASE(degrees)0 5 15 18 198 21510 12 22 24 210 22012 10 20 22 208 2188 6 16 20 200 210
    • Comparing Overall LevelsComparing Overall LevelsAcross Mounting InterfacesAcross Mounting Interfaces
    • Phase applicationPhase applicationABCA 5 Microns, 10 degreesB 7 Microns, 12 degreesC 25 Microns, 175 degreesBolt at C is loose
    • Vibration Analysis ofCommon ProblemsCommon Problems
    • Vibration AnalysisUnbalance• Amplitude proportional to the amount ofunbalance• Vibration high normally in radial direction(may be also in axial direction incase ofoverhung and flexible rotors ).• 1* RPM vibration is greater than 80%(normally) of the overall reading.
    • Vibration AnalysisUnbalance• Horizontal and vertical 1* RPM amplitudeshould be nearly same, although it alsodepends on system rigidity on theparticular direction.• Other frequency peaks may be less than5% of the 1*RPM amplitude• Phase shift of 90 deg. When sensormoves from horizontal to vertical.
    • UNBALANCE• Operating conditions such as load, flowcondition and temperature effectunbalance– Balance under normal operating conditions• Changes in track and pitch angle of fanblades can result in “AerodynamicUnbalance”
    • Typical Spectrum ForUnbalance
    • MISALIGNMENT• BIGGEST PROBLEM INITIALLY• Operating temperature can affectalignment– Machines aligned cold can go out whenwarm• Bases or foundations can settle• Grouting can shrink or deteriorate• Increases energy demands
    • MISALIGNMENT• Forces shared by driver and driven (notlocalized)• Level of misalignment severity isdetermined by the machines ability towithstand the misalignment– If coupling is stronger than bearing thebearing can fail with little damage to thecoupling
    • Three Types of Misalignment• Combination (most common)• Angular• Parallel or Offset
    • General Characteristics OfMisalignment• Radial vibration is highly directional• 1X, 2x, and 3x running speeddepending on type and extent ofmisalignment– Angular 1x rpm axial– Parallel 2x rpm radial (H & V)– Combination 1,2,3x rpm radial andaxial
    • Typical Spectrum forMisalignment
    • Vibration AnalysisMisalignmentAngular Misalignment• High axial vibration( Greater than 50% of the radial vibration)• 1* , 2*, 3* RPM normally high.• 180 deg. Out of phase across the coupling
    • Angular Misalignment• Produces predominant 1x rpm component• Marked by 180 degree phase shift across thecoupling in the axial direction
    • Vibration AnalysisMisalignmentOff-Set Misalignment• High Axial vibration. Also shows high radialvibrations.• 1*, 2*, 3* RPM high. 2* often larger than 1*• In case of severe misalignment, much highharmonics (4* - 8*) or even a whole series ofhigh frequency harmonics will be generated.• 180 deg. Out of phase across coupling
    • Parallel Or Offset Misalignment• Produces a predominant 2x rpm peak in thespectrum• Marked by 180 degree phase shift across thecoupling in the radial direction.
    • Typical Spectrum forMisalignment
    • Axial Phase ShowingMisalignment
    • Other Types Of Misalignment
    • Vibration AnalysisMechanical LoosenessCaused by structured looseness / weakness ofmachine feet, base plate or foundation; also bydeteriorated grouting, loose base bolts anddistortion of the frame or base.• Radial vibration high• 2* RPM & 1* RPM dominant• 180 deg. Phase differences between matingsurfaces which have looseness betweenthem.
    • Vibration AnalysisMechanical LoosenessCaused by structured looseness / weakness ofmachine feet, base plate or foundation; also bydeteriorated grouting, loose base bolts anddistortion of the frame or base.• Radial vibration high• 2* RPM & 1* RPM dominant• 180 deg. Phase differences between matingsurfaces which have looseness betweenthem.
    • Looseness• Looseness produces2X RPM Freq.
    • Vibration AnalysisMechanical LoosenessCaused by looseness in bearing housing bolts andcracks in the frame structure.• Radial vibration high• 2* RPM normally dominant. 0.5*, 1* and 3* RPMmay also be present• Substantial Phase difference between matingsurfaces which have looseness between them
    • LOOSENESS• Not an exciting force• Allows exciting frequencies alreadypresent to exhibit much higheramplitudes• Loss or reduction in normal stiffness• Caused by:– loose mounting bolts– deterioration of grouting– cracked welds
    • Two Types Of Looseness• Looseness of Rotating Components– Loose Rotors– Bearings Loose on the Shaft or in Housing– Excessive Sleeve Bearing Clearances• Looseness of Support System– Loose Mounting Bolts– Grouting Deterioration– Cracks– Poor Support– Frame Distortion
    • Looseness Of RotatingSystem• Rattling condition cause impacts due toexcessive clearance in a rolling elementor sleeve bearing• Impacts cause multiple running speedharmonics to appear in the spectra• Identified by:– multiple harmonics– unstable phase– highly directional radial vibration
    • Typical Spectrum for Loosenessof Rotating System
    • Looseness Of Support System• FFT readings show 1x rpm, 2x rpm, and 3xrpm components• Structural looseness / weakness will causehigh 1xrpm peak in FFT• Identified by– Highly directional radial vibration– Bouncing– Taking comparative phase readings acrossinterfaces and look for amplitude variation– Typically loose in vertical direction
    • Looseness Of Support System
    • Modern TrendinVibration Technology
    • Condition MonitoringSystem IntegrationSOFTWARE DCSCMMSNETWORKPdM TECHNOLOGIESON-LINEANALYSISSURVEILLANCEON - LINEPERIODICWALKAROUNDOFF- LINECENTRALISEDPROTECTIONDISTRIBUTEDPROTECTIONCONTINUOUSPROTECTION
    • Overall Data Acquistiontime waveformTHE DCSMONITORDCS OUTPUT4-20mA
    • current valueOverall Data Trends-this is what the DCS recordslo alarmhi alarmchanges over timeThe limitation is that it does not adequately reflect changesat higher frequencies which can increase by 100% but only add1% to the overall energy level
    • Vibration Analysistime waveformtransducerVibration SpectrumData CollectorProtection Monitorand / or
    • Band Alarms, associate with each rotating elementfrequency bandshi alarmlo alarm
    • Band Trending, the new way forwardlo alarmhi alarmchanges over timeTrend and alarm the:•Machine unbalance•Alignment•Gear mesh•Bearings etc
    • Emonitor Odyssey: spectrum band alarming though itsdiagnostic tools feature for both On & Off line gives advancedmachinery analysis and reduces False Alarms
    • EMONITOR Odyssey: Frequency BandTrendsFrequency Trend of Single Measurement
    • DIAGNOSTICS - the advantage of frequency band trending• Root cause analysis is a complex machinespecific exercise considering all eventualities• Expert systems are a one off diagnosis and donot show a trend• Frequency band trending is specific to root causeanalysis• Band alarming also indicates vibration signalsthat are outside the established norms• Trending alignment, unbalance, gear meshingand bearing condition condition is more specific• A complex issue simplified without the need ofspecialist customisation and regular updates
    • DCS Limitations - Summary• We have shown that putting total belief in the DCSvibration trend is highly risky• Machinery failures still happen with on-line vibrationmonitoring with 4-20mA data to the DCS. Most causesare due to higher frequency signals swamped by theoverall levels.• Advanced machinery protection through Frequency BandTrending and Alarming - more specific than an Expertsystem.• The latest S/w based Analysers incorporates NarrowBand Alarming. They offer machinery protection andnarrow band alarming.• A lower cost solution is periodic manual Data Collection.
    • ESHAPE: Modal analysis using phase foradvanced diagnosis and better understanding ofsystem response
    • On line Vibration and othermonitors• Innovative, fully-digital design• Exceeds API 670 specification• Widely-used system• Fully field programmable• Low installation cost• ModBus protocol
    • TYPICAL APPLICATIONTACHOTACHOMONITORVIBRATIONIRDVIBRATIONMONITORIRDTACHO TACHO TACHO TACHOVIBRATIONMONITORCH.1 CH.2IRDVIBRATIONMONITORIRDCH.1 CH.1CH.2 CH.2CH.1VIBRATIONMONITORIRDMONITORVIBRATIONCH.2 CH.1IRDTACHOTACHO TACHO TACHOCH.2MONITORVIBRATIONCH.1IRDMONITORVIBRATIONIRDCH.1VIBRATIONMONITORVIBRATIONCH.2 CH.1 CH.2 CH.1 CH.1CH.2MONITORIRD IRDHPDRIVERSDRIVERS DRIVERS DRIVERSIPTACHO TACHOMONITORVIBRATIONIRDCH.1CH.2 CH.2VIBRATIONMONITORCH.1 CH.2IRDTACHOVIBRATIONMONITORIRDCH.1CH.2TACHOCH.2 CH.1 CH.2VIBRATIONMONITORIRDDRIVERSDRIVERSLPDRIVERSALT.
    • FS HP LP GEN EXTURBINESUPERVISORYSTATOR ENDWINDINGCWPBFPBFP IDFDPAAUXILIARIESENGINEERINGOPERATIONSDCS ODYSSEYSERVERPOWER PLANT INTEGRATIONGATEWAYTO CMMSVIBRATIONANALYSERDATALOGGER
    • ENGINEERINGDCS ODYSSEYCLIENT SERVERGATEWAYTO CMMSANURAKSHANVIBRATIONANALYSERPlant Integration with LAN or WANFS HP LP GEN EX FS HP LP GEN EX FS HP LP GEN EXCONTROL ROOM No 1 CONTROL ROOM No 2 CONTROL ROOM No 3TG 1 TG 2 TG 3ETHERNET
    • NETWORKING THE INFORATION - LAN/ WAN e.g.NOIDA HQCM CELLVINDHYACHALRIHANDTALCHERUNCHAHARKAYAMKULAMPLANTOPERATIONSGATEWAYTO CMMSANURAKSHAN
    • Using PlantLinkVibration Trend PlotDigital Picture of PlantHyperlink toequipmentHierarchyAutomatic E-Mail notification onEquipment Alarm StatusClick on MeasurementLabel to link to plots orother views.
    • Information however you want it !
    • X-Window Screen Captures
    • Scenario of Instruments &Sensors & Probes• Velocity sensors are made in India• Accelerometers range over 150 types– standard– Low frequency– High temperature (Gas Turbines)– Special application• Eddy current probes - comprehensive range• Others available for process measurement
    • Vibration DatacollectorsMany vendorsSelect on ‘Fitnessfor Purpose’Intrinsic SafetyDust & Moisture proofDiagnostic Capability