Introduction to Basics of Condition Monitoring & Vibration Analysis
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Introduction to Condition Monitoring & Vibration Analysis
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A presentation i prepared on the Basics of Condition Monitoring, and with specifics to Vibration Analysis. A very simple on indeed! For people who want to start with the basics of Vibration Analysis.
Transcript of Introduction to Basics of Condition Monitoring & Vibration Analysis
Introduction to Condition Monitoring &
Vibration Analysis
Low Maintenance Costs Greater Machine Availability Lesser Manpower Usage Lesser Energy Consumption
Today's Requirement
2005 2006 2007 2008 2009 20100
20
40
60
80
100
120
Maintenace CostManpower UsageEnergy Consumption
2005 2006 2007 2008 2009 20100
102030405060708090
100
Machine Availibility
Machine Availibility
Imagine that the bearing or the blades of a steam turbine have been running for years in a power plant, and remain unattended and its condition not monitored. Without any monitoring system in place, it is tough to predict the reliability of the equipment, and predicting the potential failure mode of the same becomes almost impossible.
Poor maintenance practices and no monitoring can be detrimental and lead to catastrophic failure and cause significant damage to life and property.
Background
Reactive MaintenanceAllow machinery to run to failure.Repair or replace damaged equipment when obvious problems occur.
Preventive MaintenanceSchedule maintenance activities at predetermined time intervals.Repair or replace damaged equipment before obvious problems occur.
Predictive MaintenanceSchedule maintenance activities when mechanical or operational conditions warrant.Repair or replace damaged equipment before obvious problems occur.
Reliability Centered MaintenanceUtilizes predictive/preventive maintenance techniques with root cause failure analysis to detect and pinpoint the precise problems, combined with advanced installation and repair techniques, including potential equipment redesign or modification to avoid or eliminate problems from occurring.
Maintenance Philosophies
A survey concluded that for a specific plant in consideration, the maintenance costs varied significantly if Maintenance Philosophies changed.
Case Study Comparison
Philosophy Reactive Preventive Predictive Reliability Centered
Cost 18 $/hp/year 13 $/hp/year 9 $/hp/year 6 $/hp/year
Vibration Analysis Thermographic Analysis Oil Analysis Wear Debris Analysis Thickness Monitoring Current & Load Analysis
Condition Monitoring
The use of condition monitoring allows maintenance to be scheduled, or other actions to be taken to avoid the consequences of failure, before the failure occurs.
Condition Monitoring, Why?
Vibration Analysis
Avoids Wastage of Energy Avoids Premature Failure of Machine Components Reduces Maintenance Costs Lesser Maintenance Man-hours
Why Monitor & Analyze Vibrations?
Worst Case
Destruction of a Steam Turbine Driven Generator
Vibration is the physical movement or oscillation of a mechanical part about a reference position.
Vibration?
Amplitude◦ Magnitude of Vibration.
Frequency◦ How many time does a machine vibrate in a specific unit of time.
Phase◦ How is a machine vibrating with reference to a specific point.
Terminology
Vibration Vs. Time
Rotation
Heavy Spot
1 revolution
Time
Amplitude
0
+
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3600 rpm = 3600 cycles per minute60 Hz = 60 cycles per second
Order = One times turning speed
360 degrees
1000 rpm 1 Revolution
Time
Amplitude
0
+
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4 blades = vibration occurs 4 times per revolution4 x 1000 rpm = vibration occurs at 4000 cycles per minute
= 4000 cpm
12 toothgear
1000 rpm 1 revolution
Time
Amplitude
0
+
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12 teeth are meshing every revolution of the gear12 x 1000 rpm = vibration occurs at 12,000 cycles per minute
= 12,000 cpm
Time0
+
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Time0
+
Time0+
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Time Waveform contains all the different frequencies mixed together
Complex Time Waveform
Time0
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+
Time Waveform contains all the different frequencies mixed together
Complex Time Waveform
Amplitude
Frequenc
y
Amplitude
Time
Amplitude
Time
Amplitude
Time
Frequency
From Time to Frequency Waveform
Time0
-
Time0
+
Time0+
-
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Frequency
Frequency
Frequency
1x
4x
12x
Unbalance Misalignment Looseness Bearing Faults Gear Faults
For Motors; Stator Eccentricity Eccentric Rotors Rotor Problems Thermal Bow
Few Common Vibration Causing Problems
Predefined Spectrum Bands
20000
0.30.6
0.9
1.21.5
1.81xRPM - BALANCE
2xRPM - ALIGNMENT
3-5xRPM - LOOSENESS
500010000
15000
Frequency Hz
5-25xRPM 25-65xRPM
ANTI-FRICTION BEARINGS & GEARMESH
Unbalance-Potential Causes
Unbalance-Potential Causes
TG 4 Alternator Unbalance vs. Balanced
TG 4 Alternator Unbalance vs. Balanced
Misalignment-Potential Causes
Offset, or Parallel – the shafts are parallel to each other, but are not co-planar, or in the same plane. This can be both vertical and horizontal.
Angular – the shafts are not in the same plane, which causes a difference in measurement between measurements made 180 degrees opposite on the coupling faces.
Misalignment & Looseness
Bearing Faults–Potential Causes Function of the Geometry of the Bearing
Outer Race(BPFO)
Inner Race(BPFI)
Ball Spin(BSF)Cage
(FTF)
Localised surface damage Wear or inadequate lubrication Tooth root cracks, missing tooth Pitch error Eccentricity
Gear Faults–Potential Causes
Motor Problems appear on the spectrums usually as line frequency or multiples of line frequency.
Line Frequency is 3000CPM in our case.
Motor Problems
http://www.reliabilityweb.com/fa/vibration.htm http://www.vibrationschool.com/ http://www.plantservices.com/articles/2006/154.html http://www.howtodothings.com/education/how-to-understand-the-
basics-of-vibration-analysis http://www.cdnova.com/Portals/0/Basics%20of%20Vibration%20An
alysis.pdf
Few Useful Resources
