On-line Motor Monitoring - Vibration

1 On-line Motor MonitoringJoe GeimanJoe GeimanBaker Instrument Instrument are wereallyafter?Induction Motor and VFD applications Reduce unscheduled downtimeReduce unscheduled downtime Indicates root cause analysisIndicates root cause analysis Save $ $ $Save $ $ $ Motor Failure Areas:IEEE StudyEPRI StudyMotor Failure Areas:IEEE StudyEPRI StudyBearing44%Rotor8%Other22%Stator26%B earing41%Other14%Rotor9%Stator36% Motor Failure Causes:IEEE StudyMotor Failure Causes:IEEE Study0%20%40%60%80%100%BearingWindingEle ctrical FaultMechanical BreakageInsulation BreakdownOverheatingSafety and Connecting:Low Voltage (Less than 600V)MotorMCCLoadBreakerStep one:Running motorStep two:STOP motorStep three: Connect ExplorerStep four:Run and testStep five.

2 STOP motorStep six:Disconnect ExplorerExplorerSafety and Connecting:Medium and High Voltage (Morethan 600V)MotorLoadCTsBreakerStep one: Motor is runningStep two:Connect Explorer CTsStep three: Connect ExplorerPTsExplorerPTsMotorCTsBreakerPTs EPExplorerFirst EnergyRC Pump1 of 700+ EPs at one customerAcquire Data:Safe, Fast & Easy W/ EP-1 Power Quality Analysis PQ CapabilitiesPQ Capabilities Voltage and Current level, unbalanceVoltage and Current level, unbalancedistortionsdistortions KvarsKvars, KVA, KW s, Power factor, Crest, KVA, KW s, Power factor, Crestfactor, Harmonic bar chartfactor, Harmonic bar Overheating II22R LossesR LossesMotor CurrentsMotor Currents 100% rated Current100% rated Current100% rated Temperature100% rated Temperature 110% rated Current110% rated Current121% rated Temperature121% rated TemperatureFan 1 hp 1740 rpmMotor Condition: Broken RotorbarRotorbar Frequency:slipSynchronousrotor bar [RPM ][Hz].

3 Slip21synchoperatsynchfundrotorbarRPMRPM RPM ssff Depends on SLIP! Harder to assess with lesser load Harder to assess with bigger Motor Harder to assess with more efficient motorIncreasing Lines of Resolution:Increasing Lines of Resolution:New Rotorbar y-axis Scale ].[down'dB'Good Rotor BarBad Rotor BarCase Study 1 2A High Pressure Pump2A High Pressure Pump ProblemProblem Serious vibrationSerious Vibration Vibration ReadingVibration Reading High 7200 High 7200 Turn off Motor 7200 peek disappearsTurn off Motor 7200 peek disappears Electricians do not believe it could be a rotor barElectricians do not believe it could be a rotor bar They have never seen a rotor problemThey have never seen a rotor problem Electricians have no way to confirm or deny theElectricians have no way to confirm or deny theallegations of the mechanicsallegations of the mechanicsShow Data 2A high Pressure Pump2A high Pressure Pump Broken Rotor

4 BarBroken Rotor Bar 1C high Pressure Pump1C high Pressure Pump Good Rotor BarGood Rotor Bar2A High Pressure PumpBroken Rotor Bar2A High Pressure PumpBroken Rotor Bar1C High Pressure PumpGood Rotor Bar (comparison)1C High Pressure PumpGood Rotor Bar (comparison)Conclusion2A High Pressure Pump Recommendation to customerRecommendation to customer It appeared to be a brokenIt appeared to be a broken All thought, only slightly into the cautionAll thought, only slightly into the cautionwe questioned how saver the problemwe questioned how saver the problemwaswasResults2A High Pressure Pump3 Broken Rotor BarsResults2A High Pressure Pump3 Broken Rotor BarsCase Study 24a PA Fan Problem Slight vibrationProblem Slight vibrationBroken Rotor BarBroken Rotor BarCase Study 3 Rotor IssueRotor Issue Show need for higher acquisitionShow need for higher acquisition Show other places in spectrum toShow other places in spectrum torepresent or confirm rotor issuesrepresent or confirm rotor issuesLow Resolution DataNo Assessment Can Be MadeLow Resolution DataNo Assessment Can Be MadeHigh Resolution DataAssessment Can Be MadeHigh

5 Resolution DataAssessment Can Be MadeResults Inspection found brazing issues at theInspection found brazing issues at theend ring causing high resistance ring causing high resistance Melting Off Rotor BarsRepresenting Excessive HeatCracked End Ring (Case Study 4) Motor Current Signature AnalysisValues From Technical Associates. 54 60 dBExcellent54 60 dBExcellent 48 54 dBGood condition48 54 dBGood condition 42 48 dBModerate condition42 48 dBModerate condition 36 42 dBRotor bar crack36 42 dBRotor bar crackdeveloping ordeveloping orhighhighresistance joints. 30 36 dBmultiple cracked / broken30 36 dBmultiple cracked / brokenbars or end ringsbars or end ringsindicatedindicated < 30dBmultiple cracked /< 30dBmultiple cracked /broken bars orbroken bars orend-rings very likelyend-rings very likelyCurrent signature: FFT vs.

6 DFLLA mplitude: 20dBAmplitude: 60dBResolution: : : High Amplitude and Frequency Resolution Requires constant torque level Torque ripple Next one breaks sooner Current increases Temperature increases Insulation life shortens Typically non-immediate deathMotor Condition:Broken Rotorbar issuesMotorMCCLoad1. frequency2. speed3. Torque4. Power5. Voltage6. CurrentChain of events:Cause and effectNSFFIIF: ForceI: Current: FluxCalculating Torque:Flux: Generated by stator VoltageRotor Current: Monitored with Stator CurrentTT(t) = f( V(t), I(t) )According to Park s theory, Torque: Explorer showed that not all motors run at constantExplorer showed that not all motors run at constantoperating condition.

7 The 4 motors at the center displayoperating condition. The 4 motors at the center displaya larger variability to their operation. These are thea larger variability to their operation. These are thelocations which motors break with unusually highlocations which motors break with unusually The maintenance supervisor noted that some stirringpool motors (decontamination and recycling process)break with unusually high study I: Hydro-mechanical resonance. study I: Hydro-mechanical resonance. study I: Hydro-mechanical resonance. study I: Hydro-mechanical resonance. Brewery. The maintenance supervisor noted that some stirringpool motors (decontamination and recycling process)break with unusually high frequency.

8 The Explorer showed that not all motors run atconstant operating condition. The 4 motors at thecenter display a larger variability to their are the locations which motors break withunusually high frequency. The Torque Ripple graphs clarified the source of theoperation s study I: Hydro-mechanical resonance. study I: Hydro-mechanical resonance. study I: Hydro-mechanical resonance. study I: Hydro-mechanical resonance. action:4160V submersible pumpTorque Signature:Torque Ripple vs. # Torque Ripple vs. # Torque vs. Frequency:Mechanical Imbalance Investigating Vibration and torque forinaccessible loads:Comparison of Duct-Mounted Vibration and InstantaneousAirgap Torque Signals for Predictive Maintenance of Vane AxialFans.

9 Comparison of Duct-Mounted Vibration and InstantaneousAirgap Torque Signals for Predictive Maintenance of Vane AxialFans .Don DoanTexas UtilitiesErnesto WiedenbrugBaker Instrument CompanyDon DoanDon DoanTexas UtilitiesTexas UtilitiesErnesto WiedenbrugErnesto WiedenbrugBaker Instrument CompanyBaker Instrument CompanyPresented in IEEE CMD / 2005 Ulsan, KoreaPresented in IEEE CMD / 2005 Ulsan, KoreaProblem Application:Problem Application: A Vane Axial Fan s failure can result inunplanned outages, health and safety costs, andextensive damage to surrounding equipment. A Vane Axial Fan s failure can result inA Vane Axial Fan s failure can result inunplanned outages, health and safety costs, andunplanned outages, health and safety costs, andextensive damage to surrounding damage to surrounding equipment.

10 Vane Axial Fans are commonin nuclear environments It is almost impossible topredict bearing faults forVane Axial Fans. Vane Axial Fans are commonin nuclear environments It is almost impossible topredict bearing faults forVane Axial Comanche Peak StationTXU ElectricHorizontalApplicationVerticalApp licationVane-axial Fan Maintenance Challenge:Vane-axial Fan Maintenance Challenge: Application frequently called: Fan-in-a-can Impossible to monitor with preferred technology( Vibration on bearing housing) Cost prohibitive to issue a change in design for all Vane axial Fans for this Nuclear PowerPlant. (Nuclear Industry in average cost permeter of retrofitted wire > U$ 5,000) Application frequently called: Fan-in-a-can Application frequently called: Fan-in-a-can Impossible to monitor with preferred technologyImpossible to monitor with preferred technology( Vibration on bearing housing)( Vibration on bearing housing) Cost prohibitive to issue a change in design Cost prohibitive to issue a change in design for all Vane axial Fans for this Nuclear Powerfor all Vane axial Fans for this Nuclear PowerPlant.