Sleeve bearing diagnostics r1 05 2008
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Sleeve Bearing Diagnostics Using
Proximity Probes
Charles Phelps
Field Engineer
GE Energy
312 Thompson Ave
Lehigh Acres, FL 33972
Basic Concepts of Rotor Dynamics
Relative Phase
ONE CYCLE
Signal A
(Y)
1. Two Signals
Amplitude
2. Same Frequency
3. Same Units
RELATIVE
PHASE
4. Either Signal May
Be Reference
5. Relative Phase is
0 to 180 degrees
Leading or Lagging
Signal B
(X)
ONE CYCLE
Time
Once Per Turn Reference Pulse
0°
-V
ONE
REVOLUTION
0°
-V
ONE
REVOLUTION
Shaft Balancing
Shaft Crack Detection
Shaft / Structural Resonance Detection
Shaft Mode Shape
Direction of Precession
Location of Fluid-Induced Instability
Source
Timebase Vibration
Characteristics
Y
X
1.
2.
3.
4.
5.
6.
7.
Vibration Amplitude
Vibration Frequency
Phase
rpm
Direction of Precession
Signal Shape
Gap
(from proximity probe)
Time
Amplitude
Time
0.2
2.0
Volts/
div.
ms/
div.
X to Y (counterclockwise)
Direction of Precession
Y
Y
X
X
Given X to Y Precession (ccw)
and (ccw) Rotation: Precession = Forward
Orbit Vibration Characteristics
1.
2.
3.
4.
X
Y
Vibration Amplitude (X & Y)
Absolute Phase (X & Y)
Relative Phase
Relative Frequency (X & Y)
vs Running Speed
X vs Y
5. Direction of Precession
6. Shape
Amplitude
X = 5.6 mils pp Y = 5.4 mils pp
Orbit Vibration Characteristics
1.
2.
3.
4.
Vibration Amplitude (X & Y)
Absolute Phase (X & Y)
Relative Phase
Relative Frequency (X & Y)
vs Running Speed
X vs Y
5. Direction of Precession
6. Shape
Amplitude
Given X to Y (ccw)
Rotation:
Forward Precession
Shaft Deflection Shape
A
B
C
D
Different Bearings, Same Speed with
Keyphasor® Marker.
E
F
Average Shaft Centerline
Position
TRAIN:
115 MW TG
45 deg
Ref: -9.76 volts
Point
ID: BRG #1 VERT
315 deg
Ref: -9.28 volts
Point
ID: BRG #1 HORIZ
Var: PROBE GAP
TRANSIENT FILE
30 SEP 88 07:02:52 to 30 SEP 88 07:42:15
AVERAGE SHAFT CENTERLINE POSITION
UP
6.0
* 07:26:4
07:26:1
*
4.0
* 07:24:5
* 07:23:3
* 07:19:2
* 07:17:1
* 07:15:0
2.0
0.0
-2.0
AMPLITUDE 0.20 mils/div
0.0
2.0
X to Y (CCW) ROTATION
1/2X Vibration
0.5X
Oscilloscope
1X
2X
Spectrum Analyzer
Vibration Signal
COMPLEX
WAVEFORM
8X
6X
TIM
3X
E
1X
Full Spectrum
POINT: Bearing 1 Vibration vertical
UP
Y
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ X
+
+
+
+
+
+
+
+
+
+
B
POINT: Bearing 1 Vibration horizontal
5.00 ms/div
4935 rpm
A
B
A
1.0 mil/div X to Y (CCW) Rotation
Amplitude: (mil pp/div)
2xA
A
B
A
2.5
B
A
A
2.0 mil/div X to Y (CCW) Rotation
B
B
2.0
1.5
2xB
1.0
0.5
0
Reverse
Vibration
-1X
0
Frequency
(Orders)
1X
Forward
Vibration
Full Spectrum
AMPLITUDE: 10.0 mils/div
POINT: PT BRG 4 VERT 0°
POINT: PT BRG 4 VERT 90°
14 SEP 93
13:17:44 4890 rpm
40
30
20
1X
10
0
-4000
-2000
Reverse Vibration
Components
Up
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
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.
10 mils/div
DIRECT
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
0
2000
4000
FREQUENCY: 200 cpm/div
Forward Vibration
X to Y (CCW) Rotation
Components
POINT: Dual Vibr OB VERT
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
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.
.
X to Y (CCW)
Rotation
POINT: Dual Vibr OB HORIZ
5.00 ms / div
4890 rpm
Full Waterfall Plot
HOW TO MAKE PHASE
MEASUREMENTS
Relative Phase
ONE CYCLE
Signal A
(Y)
1. Two Signals
Amplitude
2. Same Frequency
3. Same Units
RELATIVE
PHASE
4. Either Signal May
Be Reference
5. Relative Phase is
0 to 180 degrees
Leading or Lagging
Signal B
(X)
ONE CYCLE
Time
Deflection Shape
A
B
Once Per Turn Reference Pulse
0°
-V
ONE
REVOLUTION
0°
-V
ONE
REVOLUTION
Absolute Phase Measurements
Timing (in degrees) between two (2) points on a vibration signal,
the Keyphasor® pulse and positive peak in vibration.
Vibration
Signal
Phase
Lag
Time
Keyphasor ®
Signal
Degrees of
Rotation
0°
360°
NOTE: Frequency must be the same or harmonically related.
HOW TO INTERPRET STEADY
STATE DATA FORMATS
Timebase Vibration
Characteristics
1.
2.
3.
4.
5.
6.
7.
Time
Amplitude
Time
0.2
2.0
Volts/
div.
ms/
div.
Vibration Amplitude
Vibration Frequency
Phase
rpm
Direction of Precession
Signal Shape
Gap
(from proximity probe)
Timebase Vibration
Characteristics
Y
X
1.
2.
3.
4.
5.
6.
7.
Vibration Amplitude
Vibration Frequency
Phase
rpm
Direction of Precession
Signal Shape
Gap
(from proximity probe)
Time
Amplitude
Time
0.2
2.0
Volts/
div.
ms/
div.
X to Y (counterclockwise)
Direction of Precession
Y
Y
X
X
Given X to Y Precession (ccw)
and (ccw) Rotation: Precession = Forward
