Vibration
Vibration
Vibration
Vibration Spectrum
Roving
sensor
Reflective tape
on shaft
Tachometer
Amplitude
One revolution
360
Roving
Vibration
Sensor
Waveform
Amplitude
270 to Peak
Vibration
Tach
Trigger
Tachometer
Waveform
Time
Figure 4. Absolute phase is calculated between the tach signal and vibration waveform.
Roving Sensor
Fixed Sensor
One revolution
360
Amplitude
Fixed
Vibration
Sensor
Waveform
Amplitude
Tach
Trigger
270 to Peak
Vibration
Roving
Vibration
Sensor
Waveform
Time
37
3D
im
ag
ec
ou
rte
sy
c
of Vibrant Te
200
gy
hnolo
Figure 8. A phase shift between the foot and mount may indicate soft foot.
Phase Data
Phase Data
1
2
3
4
1
2
3
4
120
118
117
122
59
119
208
330
1
2
4
3
Straight
Twist
Vertical
25
Horizontal to Vertical
phase difference
110 25 = 85
The problem is unbalance
110
shaft
Horizontal
bearing
Figure 10. Horizontal to Vertical Phase Shift of about 90 Degrees Confirms Unbalance
Bearing
270o
270o
90o
Loose joint
Fan
Pedestal
90o90o
90o
Sole Plate
Concrete
Floor
90o
175 Phase
Shift
In Phase
In Phase
DV
phase
AV
phase
BV
phase
CV
phase
10
15
190
188
.17
.29
vibration
.26
.15
vibration
vibration
Vertical
Readings
vibration
AA
phase
CA
phase
100
In
Phase
.07
Motor
vibration
Axial
Motor
Pump
100
.04
vibration
BA
phase
DA
phase
100
Axial
Pump
100
.06
In
Phase
.03
vibration
A
H
AH
phase
BH
phase
CH
phase
DH
phase
100
105
270
279
.15
.25
vibration
vibration
In Phase
Horizontal
Readings
.13
.23
vibration
vibration
165 Phase
Shift
vibration
In Phase
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
Generator Shaft
Low Pressure
Turbine Shaft
High Pressure
Turbine Shaft
6
4 5
2 3
1
Bearing #
Motor
Pump Shaft
Tube
Sole Plate,
Concrete Base
& Floor