Industrial Approaches in Vibration-Based Condition Monitoring

Industrial Approaches in Vibration-Based Condition Monitoring
اسم المؤلف
Jyoti K. Sinha
التاريخ
25 ديسمبر 2022
المشاهدات
477
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(لا توجد تقييمات)
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Industrial Approaches in Vibration-Based Condition Monitoring
Jyoti K. Sinha
Contents
Preface xiii
Author xv
Chapter 1 Introduction 1
1.1 Condition Monitoring 1
1.2 Condition Monitoring Techniques .1
1.3 Condition-Based Maintenance 4
1.3.1 Lead-Time-to-Maintenance (LTM) .5
1.4 Summary .9
Chapter 2 Simple Vibration Theoretical Concept . 11
2.1 Equation of Motion 11
2.2 Damped System . 13
2.2.1 Equation of Motion for Free Vibration . 14
2.2.2 Critically Damped System . 15
2.2.3 Over Damped System . 15
2.2.4 Under Damped System . 16
2.3 Forced Vibration 18
2.3.1 Example 2.1: An SDOF System .22
2.4 Concept of Modeshapes .23
2.5 Machine Vibration .25
2.5.1 Rotor Dynamics .25
2.5.2 Unbalance Responses .27
2.5.3 Machine Faults . 32
2.6 Summary . 33
References 33
Chapter 3 Vibration-Based Condition Monitoring and Fault Diagnosis:
Step-by-Step Approach 35
3.1 Introduction . 35
3.2 Different Stages of Vibration Measurements and
Monitoring 35
3.2.1 Bath Tub Concept . 35
3.2.2 Stage 1—Machine Installation and Commissioning 35
3.2.3 Stage 2—Machine Operation .38
3.2.4 Stage 3—Aged Machines . 42
3.3 Summary . 43
References 43viii Contents
Chapter 4 Vibration Instruments and Measurement Steps . 45
4.1 Introduction . 45
4.2 Sensors and Their Mounting Approach 45
4.2.1 Displacement Sensor 45
4.2.2 Velocity Sensor . 47
4.2.3 Acceleration Sensor 48
4.2.4 Tacho Sensor 53
4.3 Vibration Measurement . 55
4.3.1 A Typical Measurement Setup . 55
4.3.2 Steps Involved in the Data Collection 57
4.3.3 Instrument Calibration and Specifications . 59
4.3.4 Concept of Sampling Frequency 61
4.3.5 Aliasing Affect and Anti-aliasing Filter 61
4.3.5.1 Observations .65
4.3.6 Concept of Nyquist Frequency, fq and the Useful
Upper Frequency Limit, fu .66
4.3.7 Analog-to-Digital Conversion (ADC) 67
4.4 Conversion of the Measured Data into the Mechanical Unit .70
4.5 Summary . 71
References 71
Chapter 5 Signal Processing .73
5.1 Time Signal . 73
5.1.1 Filters 73
5.1.2 Amplitude of Vibration 74
5.1.3 Integration of Time Domain Signal . 76
5.1.4 Statistical Parameters . 78
5.1.5 Comparison between CF and Kurtosis 79
5.2 Fourier Transformation (FT) .82
5.2.1 Example 5.1: A Sine Wave Signal 83
5.2.2 Steps Involved for the Computation of FT .84
5.2.3 Importance of Frequency Resolution in
Spectrum Analysis .87
5.2.4 Leakage 88
5.2.5 Window Functions .89
5.3 Computation of Power Spectral Density (PSD) 92
5.3.1 Averaging Process 92
5.3.2 Concept of Overlap in the Averaging Process 94
5.3.3 Example 5.2: An Experimental Rig .96
5.3.4 Example 5.3: An Industrial Blower 96
5.4 Conversion of Acceleration Spectrum to Displacement
Spectrum and Vice Versa 99
5.5 Short Time Fourier Transformation (STFT) .100
5.5.1 Example 5.4: An Experimental Rig . 101
5.5.2 Example 5.5: An Industrial Centrifugal Pump 101Contents ix
5.6 Correlation between Two Signals 103
5.6.1 Cross Power Spectrum . 103
5.6.2 Transfer Function (Frequency Response
Function) .104
5.6.3 Ordinary Coherence . 104
5.6.4 Example 5.6: Two Simulated Signals with Noise . 105
5.6.5 Example 5.7: Laboratory Experiments . 107
5.7 Concept of Envelope Analysis . 109
5.8 Summary . 111
References 111
Chapter 6 Vibration Data Presentation Formats . 113
6.1 Introduction . 113
6.2 Normal Operation Condition . 113
6.2.1 Overall Vibration Amplitude . 113
6.2.2 Vibration Spectrum 113
6.2.3 The Amplitude—Phase versus Time Plot 115
6.2.4 The Polar Plot . 115
6.2.5 The Orbit Plot . 116
6.3 Transient Operation Conditions . 117
6.3.1 The 3D Waterfall Plot of Spectra . 117
6.3.2 The Shaft Centerline Plot . 118
6.3.3 The Orbit Plot . 118
6.3.4 The Bode Plot . 119
6.4 Summary .120
References 120
Chapter 7 Vibration Monitoring, Trending Analysis and Fault Detection . 121
7.1 Introduction . 121
7.2 Types of Faults .125
7.3 Rotor Faults Detection . 125
7.3.1 Mass Unbalance .125
7.3.2 Shaft Bow or Bend .126
7.3.3 Misalignment . 127
7.3.4 Shaft Crack .128
7.3.5 Shaft Rub 128
7.4 Other Machine Fault Detection . 129
7.4.1 Mechanical Looseness . 129
7.4.2 Blade Passing Frequency (BPF) . 129
7.4.3 Blade Vibration and Blade Health Monitoring
(BHM) .129
7.4.4 Electric Motor Defects . 129
7.5 Gearbox Fault Detection 130x Contents
7.6 Anti-friction Bearing Fault Detection . 137
7.6.1 Crest Factor (CF) 141
7.6.2 Kurtosis (Ku) 141
7.6.3 Envelope Analysis 142
7.7 Experimental Examples 143
7.7.1 Example 7.1—Roller Bearing Defect . 143
7.7.2 Example 7.2—Rotor Faults 144
7.8 Industrial Examples . 147
7.8.1 Example 7.3—Fan with Unbalance Problem . 147
7.8.2 Example 7.4—Gearbox Fault . 148
7.9 Machines Having Fluid Bearings 151
7.10 Field Rotor Balancing 153
7.10.1 Single Plane Balancing—Graphical Approach 153
7.10.2 Single Plane Balancing—Mathematical Approach 155
7.11 Summary . 157
References 157
Chapter 8 Experimental Modal Analysis 159
8.1 Experimental Procedure 159
8.1.1 Impulsive Load Using the Instrumented
Hammer . 159
8.2 Modal Analysis 162
8.3 Experimental Examples 170
8.3.1 Example 8.1—A Clamped-Clamped Beam . 170
8.3.2 Example 8.2—Experimental Rotating Rig-1 . 178
8.3.3 Example 8.3—Experimental Rotating Rig-2 . 181
8.4 Industrial Examples . 183
8.4.1 Example 8.4—Horizontal Centrifugal Pump 183
8.4.2 Example 8.5—Vertical Centrifugal Pump . 186
8.4.3 Example 8.6—Wind Turbine . 188
8.5 Summary . 191
References 191
Chapter 9 Operational Deflection Shape (ODS) . 193
9.1 Simple Theoretical Concept 193
9.2 Industrial Examples . 198
9.2.1 Example 9.1—Steam Turbo-Generator (TG) Set . 198
9.2.2 Example 9.2—Gearbox Failure .202
9.2.3 Example 9.3—Blower with Frequent Bearing
Failure .204
9.3 Summary .207
References 207Contents xi
Chapter 10 Shaft Torsional Vibration Measurement 209
10.1 Measurement Approach .209
10.2 Extraction of Torsional Vibration Signal . 210
10.2.1 Time Domain Zero-Crossing Approach 210
10.2.2 Demodulation Approach 212
10.3 Experimental Examples 213
10.3.1 Example 10.1—Blade Vibration . 213
10.3.2 Example 10.2—A Diesel Engine . 216
10.4 Summary . 218
References 218
Chapter 11 Selection of Transducers and Data Analyzer for a Machine 219
11.1 Introduction . 219
11.2 Calculation of Machine Faults Frequencies 219
11.3 Selection of Accelerometer 221
11.4 Analysis Parameters 221
11.4.1 Time Domain Analyses 222
11.4.2 Frequency Domain Analyses .222
11.4.3 Time-Frequency Analyses 222
11.5 Features Required in the Data Analyzer .222
11.5.1 Specifications .223
11.5.2 Data Analysis Capabilities .223
11.5.3 Data Trending and Storage .224
11.6 Summary .224
Chapter 12 Future Trend in VCM .225
12.1 Introduction .225
12.1.1 Future IIoT-Based CVCM Approach .227
12.2 Approach 1: Suitable for Existing Old Plants 227
12.3 Approach 2: Suitable for New Plants .229
12.4 Summary .230
References 231
Index 233
Index
Note: Page numbers in italic and bold refer to figures and tables, respectively.
A
acceleration sensors, 48–53
acceleration spectrum, 100, 145, 205
on anti-friction bearing, 138
to displacement spectrum, conversion,
99, 99
on gearbox, 150
for healthy machine, 123
response, 164
size defects, 123, 124
accelerometer, 48, 48–49, 49
mounting, 51, 52, 53
in non-dimensional form, 51
selection, 221
specifications, 52
accuracy, 60
acoustic emission monitoring, 3
ac signal, 116
ADC (analog-to-digital conversion) process, 58,
61, 66
aged machine, 42
aliasing effect, 61, 63–66
AM (amplitude modulation), 109
amplification factor, 20–21, 32
amplitude
with DAQ device, 69
FRF, 106, 106, 167, 168, 174
linearity, 51
phase versus time data, 115, 116
spectrum, 85, 94, 162, 173
unbalance force, 32
vibration, 74–76, 76, 113, 114
amplitude modulation (AM), 109
analog-to-digital conversion (ADC) process, 58,
61, 66
angular displacement, 211
anti-aliasing filter, 61, 63–67, 66,
67, 73
anti-friction bearing fault detection, 137–140,
138, 139
CF, 141
envelope analysis, 142–143
Ku, 141–142
averaging process, 92–93, 93, 94
key elements, 96
overlap in, 94–95
B
band pass (BP) filter, 73, 74, 222
bath tub concept, 35
life cycle model, 36
modification, 43
beam acceleration response, 172
bearing(s), 38, 118
anti-friction, 38, 137, 137–140, 138
blower with failure, 204–206
CF/Ku for, 142
details, 144, 220
failed drive-end motor, 147
fluid, 151–152
FRF phase plots, 198
journal, 151
machine vibration on, 30
measurements, 39, 40
pedestal, 129, 184, 185, 199
resonance response, 139
roller, 137, 143, 143–144
STFT plot, 102
vibration acceleration, 29, 195, 205
vibration sensors, 56
Blade Health Monitoring (BHM), 129
Blade Passing Frequency (BPF), 129
Blade Tip Timing (BTT) method, 129
blade vibration, 129, 213, 213–216, 214, 214
Bode plot, 119, 120
BPF (Blade Passing Frequency), 129
BP (band pass) filter, 73, 74, 222
Breakdown Maintenance (BM), 4
BTT (Blade Tip Timing) method, 129
bump test, 159
C
calibration chart, 59
cantilever beam, 24, 24
modeshapes, 25
vibration mode, 26, 27
carrier frequency, 109
CBM, see Condition-based Maintenance (CBM)
centralized VCM (CVCM) system,
227, 227
centrifugal force, 27, 29, 29
CF (Crest Factor), 78, 141, 222234 Index
clamped-clamped beam, 170, 170–178, 171, 174,
176, 177
CM, see Condition Monitoring (CM)
coherence
composite spectrum approach, 230
computation, 162
FRF and, 108
function plot, 106, 107
ordinary, 104–105
two simulated signals with noise, 105,
105–106, 106
complimentary solution, 18–19
Condition-based Maintenance (CBM), 4, 4–5
CM leading, 6
machines for, 5
Condition Monitoring (CM), 1, 2, 36
leading to CBM, 6
techniques, 1, 3
Crest Factor (CF), 78, 141, 222
critically damped system, 15, 16
cross power spectrum, 103–104
CVCM (centralized VCM) system, 227, 227
D
D’Alembert Principle, 11
damped SDOF system, 14
damped system, 13–14
under, 16–17, 18
critical, 15, 16
over, 15–16, 16
damping ratio, 15
HPP method, 179
data acquisition (DAQ) device, 45, 56, 67
ADC using 16-bit, 68
collected data for, 70
multi-input channels, 58
signal amplitudes with, 69
data analyzer, 222
capabilities, 223
data trending and storage, 224
specifications, 223
data collection steps, 57, 57–58
data sampling rate, 61
dc signal, 116
Debris analysis, 3
demodulation approach, 212
diesel engine, 216, 218
Digital FT (DFT), 84–85
displacement sensors, 45–46
displacement spectra, 100
Doppler effect, 47–48
dynamic equilibrium, 11
E
eddy current probe, 45–46
electric motor defects, 129–130
encoder, 209–210, 210, 213
signal, 215
envelope analysis, 222
signal processing, 109–111, 110
steps, 135, 136
equation of motion, 11–13
for free vibration, 14–15
SDOF, 31
experimental modal analysis, 159, 162–169,
163, 164
clamped-clamped beam, 170–178
impulsive load using hammer, 159–162
procedure, 159
experimental rig, 213
PSD, 96
rotating rig-1, 178–180, 179, 180, 181
rotating rig-2, 181–183, 182
STFT analysis, 101, 102
with vibration instruments, 28
vibration spectrum plots, 146
F
fan-gearbox-motor (FGM), 148
Fast FT (FFT), 85, 174
fault detection process, 225
faults types, 125
field rotor balancing, 153–157
filtering process, 222
fluid bearings, 151–152
forced vibration, 18–22, 21
force sensor, 161
forward calculation procedure, 71, 71
Fourier transformation (FT), 82
computation, 84–87, 85
frequency resolution, importance, 87–88, 88
leakage, 88–89, 89
sine wave signal, 83, 83
window functions, 89–92, 90
frequency domain analyses, 222
frequency modulation (FT), 109
frequency ratio, 22
frequency response function (FRF), 104,
195–196, 198
amplitude/real/imaginary/phase, 167, 174
bearing pedestal, 185
and coherence plots, 108
computation, 162
measured, 175
non-dimensional, 169
two simulated signals with noise, 105,
105–106, 106
zoomed view, 169
FSIV (full scale input voltage), 67–68
FS (full scale) reading, 60
FT, see Fourier transformation (FT); frequency
modulation (FT)Index 235
full scale input voltage (FSIV), 67–68
full scale (FS) reading, 60
G
gearbox
conditions, 134
failure, 202, 202–203, 203
fault, 148–151, 150
fault detection, 130–135, 131, 135
single stage, 130
spectrum plots, 133
typical vibration, 132
vibration spectra, 134
gear mesh frequency (GMF), 131,
149, 150
gear ratio (GR), 130
gearwheel frequency, 212
H
half-power point (HPP) method, 168–169
high pass (HP) filter, 73, 74, 212
high pressure (HP) turbine, 198, 200
horizontal centrifugal pump, 183–186, 184, 185,
186, 227, 228
I
IAS, see instantaneous angular speed (IAS)
impulse-response method, 159, 179
impulsive response, 138, 140, 142
industrial blower system, 204, 204–206
industrial centrifugal pump, 101–103,
102, 103
industrial IoT 4.0, 227, 227
inertia force, 11
influence coefficient method, 126, 153
in situ modal tests, 159, 186–188
instantaneous angular speed (IAS),
210–212
response at EO5, 215, 216
16-cylinder diesel engine, 217
spectra, 217
waveforms, 216
instrumented hammer, 159, 160, 172
force sensor in, 161, 170
impact heads, 161
for modal testing, 171
intermediate pressure (IP) turbines,
198, 200
ISO codes, 38–39, 41–42, 122
K
kurtosis (Ku), 79, 141–142, 222
L
laser velocity sensor, 47–48
Lead-Time-to-Maintenance (LTM), 5–8
estimating, 8
for machine, 7
parameters, 8
leak detection monitoring, 3
linearity, 60
Lower LTM (LLTM), 7
low pass (LP) filter, 73, 74
low pressure (LP) turbines, 198, 200
LTM, see Lead-Time-to-Maintenance (LTM)
lubricant monitoring, 3
M
MAC (modal assurance criteria), 176–177, 178
machine critical speeds, 119
machine fault detection, 129
BHM, 129
BPF, 129
electric motor defects, 129–130
mechanical looseness, 129
machine faults
classification, 228
frequencies, 219, 220–221
machine vibration, 32, 33
machine learning (ML) approach, 227–228
machine vibration, 25
on bearing housing, 30
machine faults, 32, 33
rotor dynamics, 25–26, 28, 29
under rotor unbalance, 31
sinusoidal response, 31, 32
unbalance responses, 27, 29–32, 30
magnification factor, 20
mass unbalance, 125–126
mean LTM (MLTM), 8
mean-time-to-failure (MTTF), 1
mechanical looseness, 129
ML (machine learning) approach, 227–228
modal assurance criteria (MAC), 176–177, 178
modal testing, 162; see also experimental modal
analysis
modeshapes concept, 23–25, 24
cantilever beam, 25
for clamped-clamped beam, 177
experimental rig-1, 181
experimental rig-2, 183
extraction, 176–177
machine, 193, 194
measured, 183
at natural frequency, 184, 184
normalized, 176
pump assembly and, 187
rotor, 28236 Index
motor defects, features, 130
motor-gearbox-fan unit, 149, 202, 202
N
natural frequency, 12
noise monitoring, 3
non-destructive test (NDT) techniques, 1, 3
non-dimensional CF, 142
normal operation condition
amplitude, 115, 115
orbit plot, 116–117, 117
polar plot, 115, 115
vibration amplitude, 113, 114
vibration spectrum, 113, 114, 115
O
ODS, see operational deflection shape (ODS)
analysis
oil whip/whirl, 151–152, 152
operational deflection shape (ODS)
analysis, 36
at critical speeds, 201
gearbox failure, 202–203
at gear mesh frequency, 203
industrial blower system, 204–206
at motor-blower unit, 206
motor-gearbox-fan, 203
at operating speeds, 202
rotating machine, 193, 194
simple theoretical concept, 193–198
steam TG set, 198–201
values at 1× and 2×, 197, 197, 199
orbit plot, 127, 152
normal operation condition, 116–117, 117
at rotor speed, 128, 128
transient operation conditions, 118
ordinary coherence, 104–105
oscillation, 11–13, 13
over damped system, 15–16, 16
P
PA-Fan, see primary air fan (PA-Fan)
particular integration, 19
pCCS (poly coherent composite
spectrum), 230
P-F (Potential Failure) curve, 40, 41
phase distortion, 51
phase versus time plot, 115, 115
piezoelectric accelerometers, 48
Planned Preventive Maintenance (PPM), 4
polar plot analysis, 154–155
poles, representation, 17, 17
poly coherent composite spectrum
(pCCS), 230
power spectral density (PSD), 93
averaging process, 92–95, 93, 94
experimental rig, 96, 97
industrial blower, 96–98, 98
primary air fan (PA-Fan), 147, 147–148, 148
proximity probes, 45–46, 47, 116
PSD, see power spectral density (PSD)
pulse train waveform, 210
from gearwheel, 211
spectrum, 212
pumps/piping
assembly, 187, 220
horizontal centrifugal, 183–186, 228
industrial centrifugal, 101–103, 102
schematic layout, 187
stool, stiffening, 188
vertical centrifugal, 186–188
R
reference signal, 53
Reliability and Maintenance Index (RMI), 6–7
repeatability, 60
reproducibility, 60
resonance, 20
fluid, 151–152
frequency, 52, 137, 139
response built-up, 20, 21
reverse calculation procedure, 71, 71
RMI (Reliability and Maintenance Index), 6–7
RMS, see root mean square (RMS)
roller bearing defect, 143, 143–144, 145
root mean square (RMS), 74–76, 113
amplitude, vibration, 114
time wave forms, 76
velocity, 124
vibration values, 124
vibration velocity, 147
rotating machine representation, 121, 122
rotor
balancing, 155, 156, 157
dynamics, 25–26, 28, 29
faults, 126, 144; see also rotor faults detection
misalignment, 127
rig speed profile, 215
with single plane unbalance, 30
solid point on, 30
unbalance estimation, 155
unbalance force, 29
rotor faults detection
mass unbalance, 125–126
misalignment, 127
shaft bow/bend, 126–127
shaft crack, 128
shaft rub, 128–129
running speeds/GMFs, 149, 150
run to failure, 4Index 237
S
sampling frequency, 61, 61, 62
at 2/1 kHz, 750 Hz, 63–64, 64
at 10/5 kHz, 63, 63
at 500/400 Hz, 65, 65
collected signals, 62
sine wave, 63
SDOF, see single degree of freedom (SDOF)
system
seismometer, 47
sensitivity method, 153
sensors and mounting approach, 45
acceleration, 48–53
displacement, 45–46
tacho, 53, 53–54, 54, 55
velocity, 47–48, 48
shaft bow/bend, 126–127
shaft centerline plot, 118, 119
shaft crack, 128
shaft misalignment, 146
shaft response, 138
shaft rubs, 128–129
conditions, 146
simulation, 147
short time Fourier transformation (STFT),
100–101
analyses, 198–199, 201
experimental rig, 101
industrial centrifugal pump, 101–103,
102, 103
signal processing
correlation between signals, 103–108
FT, 82–92
PSD, computation, 92–98
STFT, 100–103
time signal, 73–82, 92
signal waveforms, 80, 82
sine waveform, 89, 91
single degree of freedom (SDOF) system, 11,
22–23, 162
and behavior, 12
damped, 14
under damped, 18
with natural period, oscillation, 13
responses, 22
on vibrating object, 49
single plane balancing, 153
graphical approach, 153, 153–155
mathematical approach, 155–157
single stage gearbox, 130
small instrumented hammer,
photograph, 160
spectrum analysis, 194, 212
frequency resolution in, 87,
87–88, 88
measured vibration, 196
spectrum/spectra
acceleration, see acceleration spectrum
amplitude, 85, 94, 162, 173
coherence composite, 230
cross power, 103–104
displacement, 100
gearbox, 133, 134
IAS, 217
measured force, 163
normal operation condition, 113, 114, 115
plots, 85, 86, 87, 95, 205
pulse train waveform, 212
3D waterfall plot, 117–118, 118
time domain signal and, 140
velocity, 99, 100
vibration, 130
waterfall plot, 101
spring-mass system, 11–12, 23, 46
steam TG set, 198–201; see also turbo-generator
(TG) set
STFT, see short time Fourier transformation
(STFT)
T
tacho sensors, 53, 53–54, 54, 55
tacho signal, 53–54, 153, 154
temperature monitoring, 1, 3
TG, see turbo-generator (TG) set
thermography, 3
3-D waterfall plot, 117
time domain analyses, 222
time domain signal, 73, 140
integration, 76–78, 77
into segments, 93
and spectrum, 140
using STFT analysis, 101
time domain zero-crossing approach, 210–212, 214
time-frequency analyses, 222
time signal, 73
CF versus Ku, 79–82, 81, 82
filters, 73–74, 75
statistical parameters, 78–79, 79, 80
time domain signal, integration, 76–78, 77
vibration amplitude, 74–76, 76
time wave-forms, 161
torsional vibration, 209
transient operation conditions
Bode plot, 119, 120
orbit plot, 118
shaft centerline plot, 118, 119
spectra, 3D waterfall plot, 117–118, 118
transient response, 19
transition piece (TP), 188
trial-and-error approach, 36
trial run, 154
turbo-generator (TG) set, 55, 56, 198, 201238 Index
U
under damped system, 16–17, 18
Upper LTM (ULTM), 7
V
VCM, see vibration-based condition monitoring
(VCM)
velocity sensors, 47–48, 48
velocity spectra, 99, 100
vertical centrifugal pump, 186–188
vibration acceleration, 193, 195
spectrum plots, 205
vibration-based condition monitoring (VCM), 11,
32, 122, 225, 226
data processing in, 226
limitations in, 225, 227
machine, 38–39
measurement interval, 40–41
measurement locations and directions, 39,
39, 40
procedure, 38
software and instrumentations, 40
vibration severity limits, 41, 41–42
vibration data fusion concept, 229, 229
vibration data presentation formats
normal operation condition, 113–117
transient operation conditions,
117–120
vibration displacement
signal, 141, 154
velocity versus acceleration spectra, 123, 124
vibration measurements and monitoring stages
ADC, 67–69
aged machine, 42
aliasing affect and anti-aliasing filter, 61,
63–67, 66, 67
bath tub concept, 35
data collection steps, 57–58
instrument calibration and specifications, 59–60
machine installation and commissioning,
35–37, 37
machine operation, 38–42
Nyquist frequency, 66–67
sampling frequency, 61, 61, 62, 62
setup, 55–57
vibration monitoring, 3
vibration severity limits, 41, 41–42
vibration spectrum, 130
vibration transducer, 46
vibration velocity signal, 140
W
wind turbine, 188, 189, 190, 191
Z
zebra reflective strip, 209, 210

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