Sleeve bearing diagnostics r1 05 2008

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) Two Signals Amplitude Same Frequency Same Units RELATIVE PHASE Either Signal May Be Reference Relative Phase is 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 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 X Y Vibration Amplitude (X & Y) Absolute Phase (X & Y) Relative Phase Relative Frequency (X & Y) vs Running Speed X vs Y Direction of Precession Shape Amplitude X = 5.6 mils pp Y = 5.4 mils pp Orbit Vibration Characteristics Vibration Amplitude (X & Y) Absolute Phase (X & Y) Relative Phase Relative Frequency (X & Y) vs Running Speed X vs Y Direction of Precession 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 HOW TO EVALUATE PRELOADS (MISALIGNMENT) AND RADIAL POSITION MEASUREMENTS Direct Measurements Vibration and Position Rotor Speed Bearing Temperature Indirect Data Process Data Performance Data Radial Preloads Gravitational Fluidic Preloads Bearing Preloads Internal Misalignment Parallel and Angular Misalignment Pipe Strain Thermal Warping Axial Preloads Gravity (Vertical Machines) Fluidic Process Thrust Loads Differential Expansion 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 of Preload X RO TN Y BEARING CL Normal Orbit and Position Y = - 6.8 Vdc X = - 7.2 Vdc AVERAGE SHAFT CL Normal steady load downward, such as gravity Orbit and Position Indicators of Preload RO TN Y X AVERAGE SHAFT CL Abnormal Orbit and Position BEARING CL Y = - 6.2 Vdc X = - 5.8 Vdc Gap Voltage Measurement PROVIDES: Shaft Centerline Position Shaft Attitude Angle Eccentricity Shaft Trend Plots Alignment Along Shaft Radial Position Calculation Y Vertical Transducer 200 mV/mil Diametral Clearance 10 mils Horizontal Transducer 200 mV/mil X Rotor (Not to Scale) Shaft Centerline Y = - 10 Vdc X = - 10 Vdc Radial Position Calculation Y Vertical Transducer 200 mV/mil Diametral Clearance 10 mils Horizontal Transducer 200 mV/mil X Rotor (Not to Scale) Shaft Centerline Y = - 9.6 Vdc X = - 10.2 Vdc Radial Position Calculation Left mil Vertical Transducer Y Up mils 200 mv/mil Horizontal Transducer 200 mV/mil X to Scale) Shaft Centerline Y = - 9.6 Vdc X = - 10.2 Vdc Average Shaft Centerline Position Top 3.0 2.0 * 9500 * 9400 * 9200 * 8700 1.0 1200 * *500 * 8000 7600 * * 4500 *5500 * 300 0.0 -1.0 Amplitude 0.20 mils / div 0.0 1.0 X to Y (CCW) Rotation Shaft Centerline Plot Can Show Misalignment Turbine Generator Axial Position Measurements AXIAL (THRUST) POSITION Thrust Collar 12 Max 12 Max DIFFERENTIAL EXPANSION ... COMPLEX WAVEFORM 8X 6X TIM 3X E 1X Full Spectrum POINT: Bearing Vibration vertical UP Y + + + + + + + + + + + + + + + X + + + + + + + + + + B POINT: Bearing Vibration horizontal 5.00 ms/div 4935 rpm... 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