new tools for vibration cm (presentation) rams 2011 chris engdahl
DESCRIPTION
Overview of diagnostic functions imbedded in the new Bently Nevada ADAPT wind turbine monitorTRANSCRIPT
New Tools for Vibration Condition MonitoringChris EngdahlGE Energy, Measurement & Control
Solutions
5th Reliability, Asset Management & Safety (RAMS) Conference 2011
2 /GE /
April 13, 2023
Why do Predictive Maintenance?
Maintenance Planning
3 /GE /
April 13, 2023
The PdM/PM Advantage : PLANNING
F1
F0
Timeline Towards Failure
W-1
Work Execution
W-2W-4W-5W-6W-? W-3
Scheduling Process
Planning Process
Evaluation/Approval
P2 Advanced Vibration diagnostics - 5 months
P3 IR Thermography – 3 months
FunctionalFailure
Hard Failure
P0P1
Wear Debris - 6 months
P6 Hot to touch 3 days
P5 Audible noise - 2 weeks
P4 Overall Vibration Increase – 10 weeks
Better information, better planning
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April 13, 2023
Dynamic Energy Index (DEI)KurtosisSkewnessCumulative ImpulseAcceleration EnvelopingSideband Energy RatioHigh Pass Filtering
New Tools for Vibration Condition Monitoring
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April 13, 2023
• Sum energy in discrete bands• Bands correspond to component ranges• Normalize by Torque
Dynamic Energy Index (DEI)
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April 13, 2023
101
102
103
104
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
Frequency (Hz)
Am
plitu
de (
g)
Beari
ng
Pla
neta
ry S
tag
e
Inte
rmed
iate
Sta
ge
Hig
h S
peed
Sta
ge
Str
uctu
ral
DEI Frequency Bands
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April 13, 2023
Kurtosis
0 5 10 15 20 25-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
Time (ms)
Timebase Waveform, Healthy Signal
Tail
Kurtosis = 3.9
BroadCenter
0 5 10 15 20 25-8
-6
-4
-2
0
2
4
6
8
Time (ms)
Timebase Waveform, Failing Generator Bearing
WideTail
Kurtosis = 14
NarrowCenter
Variance (standard deviation squared) involves the square of differences between data and the meanVariance is the 2nd momentSkew is the 3rd moment
Kurtosis is the 4th moment. It puts more emphasis on the tails of the distribution
Spikier waveforms have higher Kurtosis
Normal vibration 3Sine wave 1.5
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April 13, 2023
Skewness Calculation
Timebase waveform is treated as a statistical set of data
Skewness = 3rd statistical moment of the set
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April 13, 2023
Generator Bearings: ESD Noise, High Skewness
0 50 100 150 200 250 300 350-5
-4
-3
-2
-1
0
1
2
3
4
5
Time (ms)
Acc
eler
atio
n (g
)
WTG128 Generator Outboard Timebase 5/20/2009 2:49:00 PM 1447 rpm; kurt = 9.87; skew = -1.95
Asymmetric noise, > 5 g (noise can be symmetric!)Kurtosis highDirect high
This noise happens only on some machines on particular bearings;probably associated with grounding brush problems
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April 13, 2023
• Passage of debris through gear mesh produces a detectable impulse.
• Use signal processing to automatically detect, measure, and accumulate a damage index.
Cumulative Impulse
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April 13, 2023
4.538 4.54 4.542 4.544 4.546 4.548 4.55 4.5520
1
2
3
4
5
6
7
8
Time (s)
g
SlavePlanetaryRotor16Apr10second1; corner = 0.1 Hz; order 2; 13 events for DI = 66 GE CONFIDENTIAL
Processing Example
AmplitudeResets
AdaptiveThreshold(12 x LP signal)
Low-pass filtered signal (red)
DecayEnvelope
Final Maximum For Event (red dot)
RectifiedSignal
EventTerminationEvent
Start
DefaultThreshold4 g
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April 13, 2023
Acceleration Enveloping Algorithm
• High pass filterExclude mechanical vibration contentInclude structural resonance frequency range
• Rectify• Envelope• FFT
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April 13, 2023
0 50 100 150 200 250 300-5
-4
-3
-2
-1
0
1
2
3
4
5
Time (msec)
Ac
ce
lera
tio
n (
g)
Amplitude modulationand envelope
Defect Repetition = IRBP
One revolution
DefectRepetitionFrequency
StructuralRinging
Impact-LikeEvent
Figure 6. Bearing elements generate a localized impact force and structural resonance response each time the damaged region is engaged.
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April 13, 2023
Sideband Energy Ratio
Frequency
Am
plitu
de
1XMesh
2XMesh
3XMesh
Healthy Gearmesh
Frequency
Am
plitu
de 1X
Mesh
2XMesh
3XMesh
Damaged Gearmesh
Low (or missing)Sidebands
Higher and/or moresidebands
Sideband Energy Ratio = S (sideband amplitudes)
Center mesh frequency amplitude
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April 13, 2023
Spectrum Data From Gearbox Test
Early In TestLittle Damage
Late In TestSignificant Damage
Very LowSidebands
HigherSidebands
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April 13, 2023
WTG 130 High Speed Gearbox
0 50 100 150 200 250 300 350-1.5
-1
-0.5
0
0.5
1
1.5
Time (ms)
Acc
eler
atio
n (g
)
WTG130 High Speed Timebase 4/27/2009 3:23:00 AM 1440 rpm; kurt = 2.99; skew = -0.14
Lots of stuff!
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April 13, 2023
0 2000 4000 6000 8000 10000 12000 140000
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
X: 1247Y: 0.1732
Frequency (Hz)
Acc
eler
atio
n (g
)
WTG130 High Speed Spectrum of Timebase 4/27/2009 3:23:00 AM 1440 rpm
X: 625Y: 0.08677
X: 503.1Y: 0.1409
X: 334.4Y: 0.05194
X: 168.8Y: 0.02408
Where is the noise?
1X and 2X HS mesh lines are strong
1X, 2X, and 3X IS mesh lines are strong
Mesh frequencies obscure the interesting stuff
Envelopingbandpass region
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April 13, 2023
To filter or not to filter…
0 1 2 3 4 5 6 7 8-1
-0.5
0
0.5
1
Revolutions of HS Shaft
Acc
eler
atio
n (g
)
WTG130P High Speed Timebase 4/27/2009 3:23:00 AM 1440 rpm; kurt = 2.99; skew = -0.14
0 1 2 3 4 5 6 7 8-1
-0.5
0
0.5
1
Revolutions of HS Shaft
Am
plitu
de (
g)
WTG130P High Speed Timebase 4/27/2009 3:23:00 AM 1440 rpm; HP filtered at 5000 Hz; kurt = 16.943
Chaos
Clarity
Kurtosis = 3
Kurtosis = 17
Who would have thought this was hiding in that?
Raw
5 kHzHPfilter
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April 13, 2023
0 1 2 3 4 5 6 7 8-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Revolutions of HS Shaft
Am
plitu
de (
g)
WTG130P High Speed Timebase 4/27/2009 3:23:00 AM 1440 rpm; HP filtered at 5000 Hz; kurt = 16.943
High-Pass Filtered at 5 kHz
Repeating patterns of 3 impulses modulated at 1X HS rotor speed
Impulses are ringing the gearbox structure
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April 13, 2023
Bently Nevada 3701 ADAPT monitor.
Introducing new condition monitoring technologies….
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April 13, 2023
Case History 1:
Generator Bearing FaultDetection & Replacement
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April 13, 2023
Generator Inboard Bearing, WTG 128, Before Replacement
IRBP Fault0 5 10 15 20 25 30 35 40 45 50
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Frequency (Orders of HSS)
Acc
eler
atio
n (g
)
WTG128 Inboard Generator Enveloped Spectrum 1/16/2009 1:47:00 PM 1347.641 rpm
IRBP Frequency
Envelope SpectrumTimebase
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April 13, 2023
Generator Inboard Bearing, WTG 128, After Replacement
0 5 10 15 20 25 30 35 40 45 500
0.2
0.4
0.6
0.8
1
1.2
1.4
Frequency (Orders of Main Shaft))
Acc
eler
atio
n (g
)
WTG128 Generator Inboard Envelope Spectrum 4/27/2009 8:51:00 AM 1426 rpmEnvelope SpectrumTimebase
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April 13, 2023
Case History 2:
Cracked Race
25 /GE /
April 13, 2023
1.5 MW Wind Turbine Gearbox And Sensor
HSSAccelerometer
High-Speed Output Shaft (HSS)Downwind Bearing
2 stage gearboxPlanetary + Parallel
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April 13, 2023
137 137.5 138 138.5 139 139.5 140-3
-2
-1
0
1
2
3
Time (ms)
Am
plitu
de (
g)
WTG137 High Speed Timebase 5/11/2009 11:18:00 AM 1240 rpm; HP filtered at 5000 Hz; kurt = 149.484
Initial DetectionSeptember 2008
RepeatingImpulses
1 RevolutionRepeating sequences of impulses
Each sequence is one defect encounteringmultiple rolling elements in load zone
Impulses are separated by element passagefrequency
Single Impulse
HSS accel timebase waveformNear full speed~5 g peak
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April 13, 2023
Initial Detection, Envelope Spectrum
Split Lines1X HSSIRBP10.8 X
1X Sidebands
Strong 1X modulation 1X + harmonics 1X sidebands on IRBP
2 overlapping series 1X + harmonics IRBP +/– 1X, 2X, … Difference visible at split lines
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April 13, 2023
April 2010Same Machine
High-Low-High
1 Revolution
DoubleImpulse
Double impulse indicates newdamage. Not separated by IRBP.
New damage is smaller than older damage.
High-low-high pattern suggestsmultiple faults.
1X line higher because of denserpattern of impulses.
Average bearing fault impulseslower, so IRBP line lower.
IRBP Line Lower1X Line Higher
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April 13, 2023
Trend Data, August Through AprilDirect
IRBP
Kurtosis
Direct changes little
IRBP decreases
Kurtosis decreases
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April 13, 2023
Inspection And Crack
RollingElement
InnerRace
Surface
Crack does not extendacross race
This was largest of 4cracks found
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April 13, 2023
Diagnostic Sequence
A clear IRBP bearing defect frequency found in the envelope spectrum
Very narrow impulse/response signatures in the timebase waveform suggested a narrow defect
Clear 1X modulation of the impulse amplitude, consistent with inner race fault
Second turbine with similar symptoms suggesting multiple faults, inspected, and cracks found
32 /GE /
April 13, 2023
Questions?