BASICS OF VIBRATION

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WELCOME
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BASICS OF VIBRATION
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VIBRATION

• CHARACTERISTICS OF VIBRATION SIGNAL
• AMPLITUDE
• FREQUENCY
• PHASE
• ORBIT

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TYPES OF VIBRATION PICK UP

• PROXIMITY PROBE
• VELOCITY PICK UP
• ACCELEROMETER

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CRITERIA FOR SELECTION OF VARIOUS TYPES OF
VIBRATION PICK UP

• PROXIMITY PROBE
• SHAFT VIBRATION MEASUREMENT
• KEY PHASER MARKER
• SHAFT CENTRE LINE POSITION
• BEST SUITED FOR 1 TO 500 HZ
• VELOCITY PICK UP
• FOR BEARING AND STRUCTURAL VIBRATION
• BEST SUITED FOR 10 TO 1000 HZ

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CRITERIA FOR SELECTION OF VARIOUS TYPES OF
VIBRATION PICK UP

• ACCELEROMETER
• FOR HIGH FREQUENCY RANGE
• BEST SUITED FOR 1000 HZ ONWARDS

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UNITS OF VIBRATION

• (A) DISPLACEMENT
• MICRONS, PEAK TO PEAK
• MICRONS, 0 TO PEAK
• MICRONS, RMS
• (B) VELOCITY
• MM/SEC, 0 TO PEAK
• MM/SEC, RMS
• (C)ACCELERATION
• M/SEC2, PEAK
• M/SEC2, RMS
• G, PEAK
• G, RMS

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UNITS OF VIBRATION
RMS
0 - Peak
Average
Peak - Peak
RMS 0.707 x (0-Peak) Average 0.637 x
(0-Peak) Peak to Peak 2 x (0-Peak)
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SHAFT ORBIT
Y
X
Proximity Probes
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INSTRUMENTS FOR VIBRATION MEASUREMENT

• VIBROMETER
• VIBRATION ANALYSER
• FFT ANALYSER

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TIPS FOR MAKING VIBRATION DATA MORE USEFUL FOR
ANALYSIS

• LOCATION OF VIBRATION PICK UPS TO BE INDICATED
• LOCATION OF PHOTOCELL TO BE INDICATED
• DIRECTION OF ROTATION SHOULD BE INDICATED
• KEY PHASER MARK ON ROTOR POSITION TO BE INDICATED
• AXIAL VIBRATION PHASE LOGGING MUST HAVE DIRECTION
  INDICATION
• NAME OF VIBRATION ANLAYSER SHOULD BE INDICATED
• VIBRATION UNITS TO BE INDICATED

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TIPS FOR MAKING VIBRATION DATA MORE USEFUL FOR
ANALYSIS

• WHILE GIVING CONTROL ROOM VALUES, SPECIFY THE
  VIBRATION UNITS AND LOCATION OF THE PICKUPS
• VIBRATION MUST BE MEASURED BY PORTABLE VIBRATION
  METER NEAR CONTROL ROOM PICKUP FOR VARYING THE
  CORRECTNESS OF CONTROL ROOM MEASUREMENT
• PICK UP SHOULD NOT BE MOUNTED LOOSE
• BRACKET FOR EXTERNAL SHAFT VIBRATION PICKUP
  SHOULD BE STIFF ENOUGH NOT TO PRODUCE
  AMPLIFICATION / RESONANCE

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TIPS FOR MAKING VIBRATION DATA MORE USEFUL FOR
ANALYSIS

• FOR CORRECT TRENDING OF VIBRATION READINGS, SAME
  LOCATION SHOULD BE USED FOR ALL PERIODIC
  MEASUREMENTS

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REASONS OF VIBRATION

• IF THE MEASUREMENT IS HEALTHY, FOLLOWING MAY
  BE THE REASONS OF VIBRATION PROBLEM
• UNBALANCE
• MISALIGNMENT
• LOOSENESS
• PIPE PULLS
• SHAFT CATENARY / BEARING LOADING
• RESONANCE
• UNEQUAL FLOW PATH CLEARANCES
• RUBBING

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REASONS OF VIBRATION

• SHAFT BOW
• OIL / STEAM WHIRL
• DEVIATED OPERATING PARAMETERS
• DEFECTIVE BEARING / ASSEMBLY OF BEARING
• VIBRATION TRANSMITTION FROM OTHER SOURCE
• GEAR INACCURACIES
• CASING DISTORSTION
• CAVITATION

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STEPS FOR RESOLVING THE VIBRATION PROBLEM

• ACCURATE MEASUREMENT OF VIBRATION DATA
• COLLECTION OF OPERATING PARAMETERS
• STUDY OF HISTORY OF VIBRATION BEHAVIOUR /
  OVERHAULING REPORTS / RECURRING PROBLEM FACED
• INTERACTION WITH OM PERSONNELS
• COLLECTION OF DETAILED VIBRATION BEHAVIOUR AT
  VARIOUS CONDITIONS OF OPERATION LIKE NO LOAD RUN,
  RUN UP, RUN DOWN, WITH AND WITHOUT EXCITATION,
  PART AND FULL LOAD OPERATION ETC.
• VIBRATION ANALYSIS TO NARROW DOWN THE REASONS OF
  HIGH VIBRATION

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STEPS FOR RESOLVING THE VIBRATION PROBLEM

• FORMULATION OF ACTION PLAN (SHORT TERM / LONG
  TERM)
• IMPLEMENTATION OF ACTION PLAN
• RESPONSE OF MACHINE AFTER IMPLEMENTATION OF
  ACTION PLAN
• FRESH VIBRATION ANALYSIS, IF THE PROBLEM PERSISTS
  
• IMPLEMENTATION OF NEW ACTION PLAN
• THE CYCLE OF VIBRATION ANALYSIS AND
  IMPLEMENTATION OF ACTION PLAN CONTINUES TILL THE
  VIBRATION PROBLEM IS SATISFACTORILY RESOLVED

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KNOW YOUR MACHINES

• KNOWLEDGE OF BEHAVIOUR FOR SIMILAR TYPE OF
  MACHINES
• VIBRATION PRONE AREAS
• INFLUENCE OF PARTICULAR OPERATING PARAMETER

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INTERNATIONAL STANDARDS ON VIBRATION

• ISO 10816 BEARING VIBRATION
• ISO 7919 SHAFT VIBRATION
• THERE ARE THREE LIMITS IN INTERNATIONAL STANDARDS
• LIMITS FOR NEW MACHINES
• ALARM LIMITS
• TRIP LIMITS

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RECOMMENDED LOCATIONS OF VIBRATION MEASUREMENTS
ON BEARINGS AS PER ISO
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RECOMMENDED LOCATIONS OF SHAFT VIBRATION
MEASUREMENTS AS PER ISO
Measuring Amplifier
Measuring Amplifier
PROXIMITY PICK-UP
45O
45O
VERTICAL
L
R
R
OR
L
SHAFT
SHAFT
HORIZONTAL
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THANK YOU