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Vibration analysis using phase
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Phase analysis: Making vibration analysis easier By Tony DeMatteo, 4X Diagnostics, LLC Figure 1. Vibration Waveform and Spectrum
Figure 2. Engine tuning using a timing light is phase analysis.
Figure 3. Absolute Phase Measurement
Figure 4. Absolute phase is calculated between the tach signal and vibration waveform.
Figure 5. Relative Phase Measurement
Figure 6. Relative Phase Calculated Between Two Vibration Waveforms
Figure 7. Pruftechnik VibXpert 2-Channel Vibration Analyzer
Figure 8. A phase shift between the foot and mount may indicate soft foot.
Figure 9. Phase identifies in-plane or twisting bearing motion.
Figure 10. Horizontal to Vertical Phase Shift of about 90 Degrees Confirms Unbalance
Figure 11. A phase shift between bolted joints indicates looseness.
Figure 12. Phase Data Indicates Parallel Shaft Misalignment
Figure 13. Shaft Operational Deflection Shape
Figure 14. Vertical Pump Operational Deflection Shape Structure Drawing
Figure 1. Vibration Waveform and Spectrum
Vibration Waveform
Vibration Spectrum
2
Pho
to fr
om h
iper
form
ance
pont
iac.
com
Pho
to fr
om h
iper
form
ance
pont
iac.
com
Figure 2. Engine tuning using a timing light is phase analysis.
Figure 3. Absolute Phase Measurement
Roving sensor
Tachometer
Reflective tape on shaft
3
One revolution360°
270° to Peak Vibration
TachTrigger
Time
Ampl
itude
Ampl
itude
One revolution360°
270° to Peak Vibration
TachTrigger
Time
Ampl
itude
Ampl
itude
Figure 4. Absolute phase is calculated between the tach signal and vibration waveform.
Figure 5. Relative Phase Measurement
Fixed Sensor
Roving Sensor
Roving Vibration Sensor
Waveform
Tachometer Waveform
4
TachTrigger
One revolution360°
270° to Peak Vibration
Time
Ampl
itude
Ampl
itude
TachTrigger
One revolution360°
270° to Peak VibrationTach
Trigger
One revolution360°
270° to Peak Vibration
Time
Ampl
itude
Ampl
itude
Figure 6. Relative Phase Calculated Between Two Vibration Waveforms
Figure 7. Pruftechnik VibXpert 2-Channel Vibration Analyzer
Roving Vibration Sensor
Waveform
Fixed Vibration Sensor
Waveform
5
37◦
200◦
3D image courtesy of Vibrant Technology
37◦
200◦37◦
200◦
3D image courtesy of Vibrant Technology
Figure 8. A phase shift between the foot and mount may indicate soft foot.
12
3
4
1 1202 1183 1174 122
Phase Data
1
2
3
4
1 592 1193 2084 330
Phase Data
Straight Twist
12
3
4
1 1202 1183 1174 122
Phase Data
1
2
3
4
1 592 1193 2084 330
Phase Data
Straight Twist
Figure 9. Phase identifies in-plane or twisting bearing motion.
6
25º
shaft
bearing
110º
Figure 10. Horizontal to Vertical Phase Shift of about 90 Degrees Confirms Unbalance
FanPedestal
Floor
90o
90o90o90o
Loose joint
90o
270o
270o
ConcreteSole Plate
Bearing
FanPedestal
Floor
90o
90o90o90o
Loose joint
90o
270o
270o
ConcreteSole Plate
Bearing
Figure 11. A phase shift between bolted joints indicates looseness.
Horizontal to Vertical phase difference 110◦ – 25◦ = 85◦
The problem is unbalance
Horizontal
Vertical
7
Phase and Magnitude Bubble Diagram Boiler Feed Pump 3580 rpm Readings in Velocity, in/sec – Peak Phase & Magnitude at 1x Turning Speed Transducer flip corrected
BMotor DC PumpA
VerticalReadings
VerticalReadings
AV BV CVphase
vibration
phase
vibration
phase
vibration
10.1710
.1715
.2915
.29190.26190.26
DVphase
vibration
188.15
DVphase
vibration
188.15188.15
HorizontalReadings
HorizontalReadings
CHBHAHphase
vibration
DHphase
vibration
DHphase
vibration
phase
vibration
phase
vibration
279.13279.13
270.23270.23
105.25105.25
100.15100.15
CA
DA
phase
vibration
phase
vibration
DA
phase
vibration
phase
vibration
100.04100.04
100.03100.03
AxialPump
AA
BAphase
vibration
phase
vibration
AA
BAphase
vibration
phase
vibration
100.07100.07
100.06100.06
AxialMotor
A
H
V
Figure 12. Phase Data Indicates Parallel Shaft Misalignment
Bearing # & Direction
Displacement (Mils P-P)
Phase (Degrees)
1X 1.72 355
1Y 1.17 76
2X 3.08 255
2Y 2.51 40
3X 1.26 42
3Y 2.56 123
4X 2.37 305
4Y 1.36 83
5X 2.62 355
5Y 0.93 83
6X 0.65 63
6Y 0.85 210 Figure 13. Shaft Operational Deflection Shape
In Phase In Phase
175◦ PhaseShift
In Phase In Phase165◦ PhaseShift
In Phase
In Phase
High Pressure Turbine Shaft
Low Pressure Turbine Shaft
Generator Shaft
2
1
4 5
6
Bearing #
3
8
Motor
Pump Shaft Tube
Sole Plate,Concrete Base
& Floor
Motor
Pump Shaft Tube
Sole Plate,Concrete Base
& Floor
Figure 14. Vertical Pump Operational Deflection Shape Structure Drawing
