Sleeve bearing diagnostics r1 05 2008

Shaft BalancingShaft Crack Detection Shaft / Structural Resonance Detection Shaft Mode Shape Direction of Precession Location of Fluid-Induced Instability Source... POINT: Dual Vibr OB V

Charles Phelps Field Engineer

GE Energy

312 Thompson Ave Lehigh Acres, FL 33972

Sleeve Bearing Diagnostics Using

Proximity Probes

Basic Concepts of Rotor Dynamics

RELATIVE PHASE

ONE REVOLUTION

Shaft Balancing

Shaft Crack Detection

Shaft / Structural Resonance Detection Shaft Mode Shape

Direction of Precession

Location of Fluid-Induced Instability Source

X

X to Y (counterclockwise)

X

Y

X Direction of Precession

Given X to Y Precession (ccw)

and (ccw) Rotation: Precession = Forward

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

A B C D E F

Shaft Deflection Shape

Different Bearings, Same Speed with

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

AMPLITUDE 0.20 mils/div X to Y (CCW) ROTATION

UP

Average Shaft Centerline

Position

0.5X 1X 2X

1/2X Vibration

+ + + + + + + + + + + + + + + + + + + + + + + + +

B A

B

1.5

1.0

0.5

UP POINT: Bearing 1 Vibration vertical

POINT: Bearing 1 Vibration horizontal

2.0 mil/div X to Y (CCW) Rotation 5.00 ms/div 4935 rpm

A A

B

Reverse Vibration

Forward Vibration

1.0 mil/div X to Y (CCW) Rotation

Frequency (Orders)

POINT: Dual Vibr OB VERT

POINT: Dual Vibr OB HORIZ

10 mils/div

DIRECT

X to Y (CCW) Rotation

Full Waterfall Plot

HOW TO MAKE PHASE MEASUREMENTS

RELATIVE PHASE

Deflection Shape

A

B

ONE REVOLUTION

0° 360°

Absolute Phase Measurements

Timing (in degrees) between two (2) points on a vibration signal, the Keyphasor® pulse and positive peak in vibration.

Vibration

Signal

Time

Phase Lag

HOW TO INTERPRET STEADY STATE DATA FORMATS

div.

ms/

div.

X

X to Y (counterclockwise)

X

Y

X Direction of Precession

Given X to Y Precession (ccw)

and (ccw) Rotation: Precession = Forward

Sinusoidal

Relative Vibration Frequency

Orbit Vibration Characteristics

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

Orbit Vibration Characteristics

X = 180° Y = 270°

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

Orbit Vibration Characteristics

X leads Y by 90°

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

Orbit Vibration Characteristics

1X

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

Orbit Vibration Characteristics

Circular

1 Vibration Amplitude (X & Y)

2 Absolute Phase (X & Y)

A B C D E F

Shaft Deflection Shape

Different Bearings, Same Speed with

Relative Phase

X leads Y by 10° - 15°

Relative Phase

X leads Y by 170° - 175°

Vibration Frequency vs

Rotative Speed

X = 1X, Y = 2X

180° OF ORBITING 360° OF ROTATION

Frequency Ratio Using Orbits

120° OF ORBITING 360° OF ROTATION

120° ORB 1 360° ROT 3

= = X

180° ORB 1 360° ROT 2

= = X

240° OF ORBITING 360° OF ROTATION

240° ORB 2 360° ROT 3

= = X

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

AMPLITUDE 0.20 mils/div X to Y (CCW) ROTATION

UP

Average Shaft Centerline

Position

0.5X 1X 2X

1/2X Vibration

+ + + + + + + + + + + + + + + + + + + + + + + + +

B A

B

1.5

1.0

0.5

UP POINT: Bearing 1 Vibration vertical

POINT: Bearing 1 Vibration horizontal

2.0 mil/div X to Y (CCW) Rotation 5.00 ms/div 4935 rpm

A A

B

Reverse Vibration

Forward Vibration

1.0 mil/div X to Y (CCW) Rotation

Frequency (Orders)

POINT: Dual Vibr OB VERT

POINT: Dual Vibr OB HORIZ

10 mils/div

DIRECT

X to Y (CCW) Rotation

Full Waterfall Plot

HOW TO INTERPRET STARTUP AND SHUTDOWN PLOTS

Slow roll speed range (no dynamic data).

rpm

2415 2310

2430 2445 2460 2475 2505 2685

2775 2985

3615 300 1845 2145

2610

Uncompensated Polar Plot

Slow Roll Vector

Angle of Heavy Spot

Uncompensated

Compensated

Balance Resonance

2205 2250

2280

2310 2370

2385 2405 2415 2430 2445 2460

2505 2610

2775 3615

1X Compensated Polar Plot

Amplitude and Direction

of Response at Balance Resonance

Amplitude and Direction

of Response Above

Balance Resonance

Direction of Mass Unbalance

Inboard Vertical

Structural Resonances

rpm

Split Critical and Structural Resonances

2385 2400 2415

2445 2460 2475 2505 2610

2685 2775 2745 3285

300 2055

2065 2400

2415 2445 2475

*

Polar Plot

Balancing Effect

Mu Before Balancing

Mu After Balancing

Two Mass Rotor System

Vertical

Probe

Vertical Probe

Mass

Typical Flexible Rotor Mode

Shapes

P1 P2P3P4

Typical Rotor

P3Cylindrical / Translational Mode

P2

Pivot / Conical Mode

P1

P4Third Mode

Node Locations are Affected by System Stiffness

4500 1200

500

300

Average Shaft Centerline

(Not Orbit or Polar Plot)

Top

Half Cascade Plot

Full Cascade Plot

HOW TO EVALUATE PRELOADS (MISALIGNMENT) AND RADIAL POSITION MEASUREMENTS

Orbit Plot Can Show Preloads

(Misalignment)

(No Resonance Near Twice Rotative Speed)

Rare Common Rare

Orbit Plot Can Show Preloads

(Misalignment)

(Resonance Near Twice Rotative Speed)

Rare Common Rare

Orbit and Position Indicators

Orbit and Position Indicators

RO

TN

Gap Voltage Measurement

PROVIDES:

Shaft Centerline Position Shaft Attitude Angle

Eccentricity Shaft Trend Plots Alignment Along Shaft

Radial Position Calculation

200 mV/mil

Diametral Clearance 10 mils

Rotor (Not to Scale)

Shaft Centerline

Radial Position Calculation

200 mV/mil

Diametral Clearance 10 mils

Rotor (Not to Scale)

Shaft Centerline

200 mV/mil

Shaft Centerline

Y

X

4500 1200

Generator

Shaft Centerline Plot Can

Show Misalignment

AXIAL (THRUST) POSITION