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Vibration Analysis:AutomatedDiagnostics
Mike CannonDLI Engineering Corp.
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Diagnostic System Development
25,000+ machines in database (since 1972 )
Rules continuously verified & updated
New rules added as unique machines join database
Fault diagnoses analytically & empirically derived
Large machine database, combined with years of repairhistory, and machine life cycle data is foundation fordiagnostic system success
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Keys to a successful program…
Ensure reliable and complete data collected
Ensure you get answers, not just data
Ensure you get First Rate support and training
Use the right technology for the right application
Distribute the information everywhere it is needed forplanning of repairs
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Reliable and complete data
Triaxial Sensor All 3 axes - more complete analysis
Improves accuracy of diagnosis
Permanently Mounted Stud Excellent frequency response
Repeatability = accurate trending
Barcoding Faster and more accurate
Prevents human error
100 100
WATCHMAN TEST POINT
DO NOT PAINT
100 100
WATCHMAN TEST POINT
DO NOT PAINT
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Processing Vibration Data
Level IReports
Level IReports
Level IIISignatures
Level IIISignatures
Level IITrends
Level IITrends
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Level 1 - Reports
Discussion: Raw diagnostic report 93% of erroneous analysis was in stating the severity level
Diagnostic software best equipped to identify obvious faults andadditional faults (complete picture)
Discussion: Engineers 67% of missed faults were where there was more than one fault,
(missed multiple fault diagnosis)
Tended to identify the obvious fault only
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SL
IGH
TE
XTR
EM
E
MARFEB APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEBJAN
= Motor Bearing Wear
Increased Frequencyof Data Collection
Greased BearingReplaced Bearing
Level 2 - Trends
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Tri-axialDisplayTri-axial
DisplayTri-axialDisplay
Single axesDisplay
Single axesDisplay
Level 3 - Signatures
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MACHINE: MAIN CONDENSATE PUMP (TD)SHIP APPLICABILITY: 61,62,63,64CVN63 UNITS: 1B,2B,3B,4B
SWAB: 255-5 MID: 53DATE: DECEMBER 1992
DRIVER INTERMEDIATE DRIVEN
CID#: 05790037MFR DWG#: 347-2918MFR: WHITONHP: 40STEAM CONDITIONS:
Chest: 575 PSIGExhaust: 15 PSIG
RPM: 6410TYPE: HELICAL FLOW,IMPULSE
CID : 05790037TECH MANUAL : 347-2918MFR: WHITONRATIO: 5.479 TO 1RPM (INPUT/OUTPUT):
6410/1170TYPE: SINGLE HELICAL,
DOUBLE REDUCTION
CID : 016000340TECH MANUAL : 347-2918MFR: ALLIS CHALMERSOUTPUT: 595 GPM @ 65 PSIGRPM: 1160TYPE: DOUBLE STAGE,
SINGLE SUCTION,VOLUTE
TEST RPM’s AND OPERATING CONDITIONS
TURBINE: 6400 PUMP: 1168
ANALYSIS RANGES
REF RPM: 1 X TURBINEORDERS: 2, 100FREQ HZ : 220, 11000
What machine is thisWhat machine is this
How does theDiagnostic System work?Incoming SpectraIncoming Spectra
Machinery Knowledge BaseMachinery Knowledge Base
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What machine is thisWhat machine is this
Incoming SpectraIncoming Spectra
Machinery Knowledge BaseMachinery Knowledge Base
VIBRATION SOURCE COMPONENTSDRIVER INTERMEDIATE OR AUXILIARY SHAFTS DRIVEN
ITEM DESCRIPTION ELEM ORDER ITEM DESCRIPTION ELEM ORDER ITEM DESCRIPTION ELEM ORDER
t
Z1
T1S1
G1
AB
Turbine Shaft (ref)
Nozzles90 Degree Spacing
Turbine BladingReversing Chambers
12.6 Degree Spacing10.5 Degree Spacing8.3 Degree Spacing
High Speed Drive Pinion
BEARING FUNCTIONSKF 6211 R,T-tSKF 6211 R-t
3
40
27
1.00t
3.00t4.00t
40.00t
28.60t34.20t43.40t27.00t
I
G2G3G5
o
G6OP
CD
Intermediate Shaft
High Speed Driven GearLow Speed Drive PinionOil Pump Drive Pinion
Oil Pump Shaft
Oil Pump Driven GearOil Pump
BEARING FUNCTIONND 41308 R,T-iND 41308 R, T-i
662925
8112
0.41t
27.00t11.86t10.23t
0.13t
10.23t1.52t
p
G4P1P2
EFGHJ
Pump Shaft
Low Speed Driven Gear2nd Stage Impeller Vanes1st Stage Impeller Vanes
BEARING FUNCTIONTMK 7320 R,T-pTMK 7320 R,T-pMRC 7308 R,T-pMRC 7308 R,T-pJournal R-p
6555
0.18t
11.86t0.91t0.91t
&what are its vibration sources?
How does theDiagnostic System work?
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What machine is this &what are it’s vibration sources
What machine is this &what are it’s vibration sources
Incoming SpectraIncoming Spectra
Machinery Knowledge BaseMachinery Knowledge Base
High SpeedDrive Pinion
BEARINGSKF 6211BEARINGSKF 6211
Oil Pump
How does theDiagnostic System work?
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Incoming SpectraIncoming Spectra
What machine is this &what are its vibration sources?
What machine is this &what are its vibration sources?
How does this spectra compareto that of a healthy machine?
How does this spectra compareto that of a healthy machine? Average Spectra Data BaseAverage Spectra Data Base
How does theDiagnostic System work?
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Baseline Data of healthy machineAverage + 1 Sigma Alarm Level
800 Alarm Levels
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Incoming SpectraIncoming Spectra
What machine is this &what are its vibration sources?
What machine is this &what are its vibration sources?
How does this spectra compareto that of a healthy machine?
How does this spectra compareto that of a healthy machine?
What, if anything, is wrong withthis machine and how bad is it?
What, if anything, is wrong withthis machine and how bad is it? Spectral Analysis Rule BaseSpectral Analysis Rule Base
How does theDiagnostic System work?
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Diagnostic Program Flow Path
CSDMCSDM
CSDMCSDM
CSDMCSDM
MOTOR
COUPLING
CENTRIFUGAL PUMP
COMPONENTCODES
SCREENINGOUTPUT TABLE
MACHINEDATA
MACHINEDATA
(CSDM = Component Specific Data Matrix)
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16 15Couplings
Component Codes
1Motor Driven
Close CoupledPumps/Fans
2Turbines
4Gearboxes
5Linked Drives(Belt/chain)
6Pumps
Centrifugal
7Rotary Thread
Pumps
8Sliding Vane
Pumps
9Axial Piston
Pumps
10Fans
11Centrifugal
Compressors
12Piston
Compressors
13Generators
14Centrifugal
Purifiers
NOTE:This illustrated set
is not complete
3Motors
3Motors
15Couplings
6Pumps
Centrifugal
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CSDM
CSDM
CSDM
MOTOR
COUPLING
COMPONENTCODES
SCREENINGOUTPUT TABLE
(CSDM = Component Specific Data Matrix)
MACHINEDATA
MACHINEDATA
FAULTTEMPLATES
Diagnostic Program Flow Path
CENTRIFUGAL PUMP
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18Diagnosis Rules
1. 2X Vertical or Horizontal > .03 IPSand
> 20% above Baseline on both sides of the coupling
3. The Maximum 2X > .06 IPSor
The sum (V & H) of 2X exceedances > 10 times the1X (V & H) for at least one side of the coupling
2. 2X Vertical > 1X Verticalor
2x Horizontal > 1X Horizontal for one side of coupling
--Misalignment (Parallel)
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CSDM
CSDM
CSDM
MOTOR
COUPLING
CENTRIFUGAL PUMP
COMPONENTCODES
(CSDM = Component Specific Data Matrix)
MACHINEDATA
MACHINEDATA
FAULTTEMPLATES
Diagnostic Program Flow Path
SCREENINGOUTPUT TABLE
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Incoming Spectra
Machinery Fault ReportMachinery Fault Report
What machine is this &what are its vibration sources?
How does this spectra compareto that of a healthy machine?
What, if anything, is wrong withthis machine and how bad is it?
Maintenance Planning
How does theDiagnosticSystem work?
Answers not just Data
We’ve automated thesame steps a humananalyst follows
It is not a black box!
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Maintenance Planning Schedule immediate repairs (Extreme Faults)
Avoid catastrophic failure or secondary damage
Schedule normal repairs (Serious Faults) Planned outage or maintenance period
Review parts availability (Moderate Faults) Stock long-lead-time parts for critical equipment
Order parts in advance for planned shut downs
Retest following maintenance or replacement Reset baseline & reference information
Verify maintenance was performed correctly
Answers not just Data
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Common Problems Identified
Imbalance
Misalignment
Ball Bearings
Looseness
Bent shaft
Journal Bearings
Gear Problems
Impeller Blade Problems
Motor Problems
650 more
Answers not just Data
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A 6 Step Approach to Condition Assessment 1
Data Acquisition (e.g. portable or online data collected from widevariety of sensors)
Data Manipulation (e.g. spectra, waveforms, envelop demodulation,phase or overall level)
State Detection (e.g. create average baseline data to be used forfuture comparison)
Health Assessment (e.g. automated fault diagnostics using rule-base expert system)
Prognostic Assessment (e.g. three levels of repair priority for takingmaintenance actions)
Advisory Generation (e.g. actionable information consists ofmachine severity, specific fault (s), repair recommendation & priority
1 International Standard ISO Standard 133741-1Condition monitoring & diagnostics of machines
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Screens Raw Data from Machine
> 500 Alarm Bands
Actual machine data is thebaseline alarm
Analyst simply selects healthymachine data
Alarm threshold generatedusing statistical models
Provides highly selectivemachine condition (fault,severity & repair priority)
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Automated Fault Diagnostics - Overview
Rule-base expert system,proven over 25 years ofexperience and use
Reduces analysis, diagnosisand report generation by anorder of magnitude comparedto manual analysis programs
Based on five levels of faultseverity and three levels ofrepair priority
Extreme
Serious
Moderate
Slight & OK
Mandatory
Important
NoRecommendation
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Automated Fault Diagnostics - Planning
Schedule immediate repairs (ExtremeFaults) to avoid catastrophic failure orsecondary damage
Schedule normal repairs (SeriousFaults) to plan outage or maintenanceperiod
Review parts availability (ModerateFaults) Stock long-lead-time parts for critical
equipment Order parts in advance for planned
shut downs
Retest following maintenance orreplacement Reset baseline & reference information Verify maintenance was performed
correctly
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Documentation & Actionable Report
Repair Priority
Repair Action /Recommendation
Problem Description withspecific fault severity
Vibration detail showingspecific amplitude andfrequency triggered fault
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Measure - Analyze - Document
Measure / Collect Data Portable or Online
Use other Technologies(Oil, IR, Motor, Ultrasound)
Analyze / Screen Data Time, Spectra, Demodulation,
Run Down, Trends, Waterfall
Document / Report / Distribute Fault, Severity, ACTION
Machine Condition Assessment (MCA)
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Analyze Data – Example: Circ Water Pump
Use ALL the tools available Spectral Pattern Recognition
Spectral Comparison
Trends
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Analyze / Diagnose – Motor Imbalance
Boiler Circulating Water Pump/Motor 1B
Report generated on: 5/30/01 05:44 PM
Acquired: 2/18/98 07:56 PM 1xM = 1794 RPMAverages: 6
Figure of Merit = 360.
Maximum level: 0.1761 (+0.1448) in/s at 1xMon 1R in low range
RECOMMENDATIONS:
IMPORTANT: BALANCE MOTOR
DIAGNOSES:
SERIOUS MOTOR IMBALANCE
Severity Levels:SlightModerateSeriousExtreme
ACTION with PriorityDesirableImportantMandatory
Specific Fault(s)Note: Over 950 faulttemplates availablefor 47 machinetypes/components
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Analyze / Diagnostic Fault Template / Rules
1 x Horizontal > 0.12 ips OR 1 x Vertical > 0.12 ips
1 x Horizontal > average baseline @ Motor
AND 1 x Vertical > average baseline @ Motor
1 x Horiz. Delta + 1 x Vert. Delta @ Motor
> 1 x Horiz. Delta + 1 x Vert. Delta @ Pump
1 x Horiz. > 1 x Axial @ Motor AND
1 x Vert. > 1 x Axial @ Motor
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Analyze / Diagnose - Shaft Misalignment
2X
2X
1X
• At Twice Rotational Rate in the Horizontal& Vertical Directions (parallel)• At the Rotational Rate in the Axialdirection (angular)
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Analyze / Diagnose – Shaft Misalignment Rule-based logic is identical to
human analyst:
High 2x amplitude in radialdirections and 1x in axialdirection
Significant exceedance aboveaverage baseline
Serious Misalignment >>Important repairrecommendation to align unit
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Analyze / Diagnose – Rolling Element Brg
Additional tools Spectral Comparison
Time Waveform
Envelop Demodulation
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Documentation / Report – Bearing Fault
Drain Pump1
Acquired: 8/19/98 10:35 AM 1xM = 1192 RPM Averages: 1
Figure of Merit = 705.
Maximum level: 0.222 (0.024) IPS [3T] at 3.00xM
RECOMMENDATIONS:
MANDATORY: REPLACE MOTOR BEARINGS
DIAGNOSES:
EXTREME MOTOR BEARING WEAR
0.088 (0.084) IPS [2R] at 3.10xM
SLIGHT PUMP INTERNAL LOOSENESS
SLIGHT MOTOR BALL BEARING SIGNIFICANT DEMOD
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Document / Distribute Information
ABB/DLIUSA
ABBAbu DhabiABB
Germany
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Tools for Information Distribution
Database replication / synchronization
Remote, web-based vibration services
Automated alarm notification via pager,text messaging or email
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Tools for Information Distribution
Web-enabled Services
Access to machine data &condition information via yourWeb Browser
View information on anymachine in database
List of Machines by Severity
Automated Diagnostic Results
Spectral Plots
Severity Trends
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Summary
Agreement with human analysts is demonstrated to bein excess of 90%
Study group of 4000 machines of many types.
Basic methods are discussed Speed normalization
Average spectra as a baseline
Cepstrum analysis for bearing tone detection
Component specific data and rules application
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Rulebase Development
Developed through systematic comparison of expert human analysis to the expertsystem analysis results
Original database of over 10,000 machine tests
Rulebase development and refinement continues
Currently our machinery test database grows at a rate of over 2000 machine tests amonth,
Every one of the tests reviewed for expert system versus human analysis agreement as partof an ongoing quality improvement program.
This regular methodical review of the results provides expert system report correctionswhich are forwarded to the plant managers
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Accuracy Study
Machine Tests Reviewed 3971
Correctly Identified Fault Free Machines 2733
Faults Reported 1183*
Correct calls 1106
Faults Missed 77
False Alarms 59
Accuracy Excluding Fault Free Units 87.8%
Accuracy Including Fault Free Units 96.1%
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More Statistics
The probability of:
A good machine being reported by automated system as faultyis 2.1%
The probability of a faulty machine being completely missed byautomated system is 5.8%
The probability of a faulty machine being misdiagnosed byautomated system is 1.4%.
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Methodology Basis 1: Machinery and Data Setup
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Forcing Frequencies
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Methodology Basis 2: Tri-Axial Vibration Data Acquisition
Acquire data for all three axes at each test point. Axial, Vertical and Horizontal (A, V, H).
At least one test location and sometimes two per major machinecomponent isolated-by a flexible coupling.
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Low Range 3-axis Sample Spectra
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Data flow
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Methodology Basis 3: Order Normalized Vibration Data
The expert system automatically finds the running speed of each machine. Order normalizing allows
Analyst or expert system quickly identify peaks
The expert system readily identifies probable bearing tones and detects rotational ratesidebands.
Most important, it allows The creation of an average data file
Combining Vibration signatures for identical machines
different times
slightly different operating speeds
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Methodology Basis 3: Order Normalized Vibration Data
Uses least squares fit between Peaks in the Current data and
Reference peaks
Faultcodes
average peaks
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Data flow
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Methodology Basis 4: Averaged Vibration Data
Accumulated average data is the baseline for automated analysis.
Allows the machines themselves to define an acceptable level ofvibration.
Composed of normalized vibration signatures of:
relatively healthy machines
physically identical machines
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Data flow
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Methodology Basis 5: Vibration Data Screening
Screening routine incorporated by an expert system produces a screening output table which includes the following information for each test location and axis:
Amplitudes at each of ten pre-selected, specified orders, (screening criteria or fault codes) 1x and 2x (one and two times rotational rate), MB (motor bar pass rate) PV (pump vane rate) GR (reduction gear mesh rate) FDN (foundation resonance).
Amplitude and rotational rate order of : the two highest peaks in each of the low range and high range spectra, excluding the ten specified peaks.
“Floor” level below which are the amplitudes of 75% of the remaining spectral lines of the high range spectrum.
For each of the above, change in amplitude deviation from average plus sigma.
Thus we have 14 distinct peaks plus the “floor” noise level tabulated for each axis
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Screening Sheet Example
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Methodology Basis 6: Cepstrum Analysis for Bearing Wear Detection
Developed to detect and identify harmonics and sidebands, Finds any significant series of regularly spaced peaks in the frequency
spectrum.
A cepstrum can be defined simply as the spectrum of a spectrum.
Characteristic peaks in the cepstral data occur at positions corresponding tofrequencies at which there exists a strong series of peaks or spacings in thespectrum.
A machine with a faulty antifriction bearing may show a harmonic series ofpeaks with 3.12 times rotational rate spacings in the spectral data (i.e. peaks at3.12,6.24,9.36... etc.).
This series of peaks would then show up in the cepstral data as a single peak ata position corresponding to the frequency of 3.12 times rotational rate.
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Methodology Basis 7: Analysis by Component
Close-Coupled MachinesTurbinesMotorsGearboxesLinked Drives (belt or chain)Centrifugal PumpsRotary Thread/Gear PumpsRotary Sliding Vane PumpsReciprocating PumpsFansCentrifugal CompressorsReciprocating CompressorsScrew CompressorsLobed BlowersGeneratorsPurifiersCouplingsDiesel EnginesMarine Propulsion GearboxesMachine Tool Spindles
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CSDMCSDM
CSDMCSDM
CSDMCSDM
MOTORMOTOR
COUPLINGCOUPLING
CENTRIFUGAL PUMPCENTRIFUGAL PUMP
COMPONENTCOMPONENTCODESCODES
SCREENINGSCREENINGOUTPUT TABLEOUTPUT TABLE
(CSDM = Component Specific Data Matrix)(CSDM = Component Specific Data Matrix)
MACHINEDATA
MACHINEDATA
FAULTFAULTTEMPLATESTEMPLATES
Diagnostic Fault Templates / Data Flow
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Diagnostic Rule-base
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Rule template example