Vibration For Non-Vibration Engineers.pdf
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Vibration for non Vibration engineer
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Vibration For Non-Vibration Engineers.pdf
- 1. VIBRATION FOR NON VIBRATION FOR NON VIBRATION ENGINEERS VIBRATION ENGINEERS
- 2. ©2005, Emerson Process Management. Types of Maintenance Strategies Types of Maintenance Strategies Run to failure Preventive maintenance Predictive maintenance Proactive Maintenance
- 3. ©2005, Emerson Process Management. Run to Failure Run to Failure Results in: – Catastrophic machine damage – Unscheduled maintenance – Lost production revenue
- 4. ©2005, Emerson Process Management. Preventive Maintenance Preventive Maintenance Better than “Run to failure” Results in: – Excessive scheduled downtime – Unnecessary maintenance – Failures due to improper maintenance
- 5. ©2005, Emerson Process Management. Predictive Maintenance Predictive Maintenance Maximizes motor life through abnormal operation and fault detection. Reduces unscheduled downtime by alerting users of degrading mechanical/electrical conditions. Optimizes motor utilization.
- 6. ©2005, Emerson Process Management. Predictive Maintenance Methods Predictive Maintenance Methods Route based methods – Vibration – Tribology – Shaft Current/Voltage – Electric Current Analysis – Temperature – Flux – Ultrasonics – Infrared Thermography – Wireless
- 7. ©2005, Emerson Process Management. Predictive Maintenance Methods Predictive Maintenance Methods Continuous (on-line) monitoring Off-line testing – Motor circuit parameter testing – Surge testing
- 8. ©2005, Emerson Process Management. Proactive Maintenance Proactive Maintenance Identify repeat failures Determine root causes for these failures Correct root cause to eliminate future failures for the same reason
- 9. ©2005, Emerson Process Management. Introduction to Vibration Objectives Introduction to Vibration Objectives Introduction to Vibration Objectives Define Vibration – What is it, where does it come from? Describe measurement methods Discuss time and frequency – Relationships between the two Examine amplitude measurements – Differences between the three Choose proper transducer – Right probe for the application
- 10. ©2005, Emerson Process Management. Introduction to Vibration Introduction to Vibration Introduction to Vibration Vibration : – Movement of a body about a reference. • Response to some form of excitation • Forcing function
- 11. ©2005, Emerson Process Management. Amplitude Amplitude Amplitude 3 ways to display – All three show severity – Some better than others Displacement – Distance a body moves – Point “A” to point “B” Velocity – Measures the speed – Time from point “A” to point “B” – rate of displacement Acceleration – Total force acting – Change of direction
- 12. ©2005, Emerson Process Management. Sources of Vibration Sources of Vibration Sources of Vibration Imbalance Misalignment Belts Gears Bearings – Rolling Element – Sleeve Looseness Electrical Anomalies Oil Instability Resonance
- 13. ©2005, Emerson Process Management. Choose units for optimum data display Choose units for optimum data display Choose units for optimum data display (D) isplacement Mils Peak-to-Peak (V) elocity In/Sec Peak (A) cceleration G’s RMS D V A
- 14. ©2005, Emerson Process Management. Vibration Terms Vibration Terms Vibration Terms Phase – relationship between two events relative to a reference Amplitude – measurement of energy of a vibrating object Displacement – distance a body travels – units of mils (pk. to pk.) Velocity – rate at which displacement occurs – units of inches per second in/sec (pk.) or mm/sec RMS Acceleration – rate of change of velocity – units of G’s (RMS)
- 15. ©2005, Emerson Process Management. Vibration Terms, cont’d Vibration Terms, cont Vibration Terms, cont’ ’d d Frequency – how often an event occurs per unit time Units – CPS • cycles per second ( Hz) – CPM • cycles per minute – RPM • revolutions per minute – Orders • multiples of Turning Speed
- 16. ©2005, Emerson Process Management. Measurement Parameters Measurement Parameters Measurement Parameters 2 Domains : TIME and FREQUENCY FFT FFT
- 17. ©2005, Emerson Process Management. Time domain data Time domain data Time domain data Helpful : – Calculating frequencies – Detect faults not frequency domain – Confirm / deny suspected anomalies
- 18. ©2005, Emerson Process Management. Vibration – Overall Trend Vibration Vibration – – Overall Trend Overall Trend
- 19. ©2005, Emerson Process Management. JUL AUG SEP OCT Vibration – 1 x RPM Vibration Vibration – – 1 x RPM 1 x RPM
- 20. ©2005, Emerson Process Management. Vibration – High Frequency Vibration Vibration – – High High Frequency Frequency
- 21. ©2005, Emerson Process Management. Vibration – Bearing Frequencies Vibration Vibration – – Bearing Frequencies Bearing Frequencies High frequency peaks – Usually non-synchronous peaks (with sidebands)
- 22. ©2005, Emerson Process Management. Vibration – Time Waveform Vibration Vibration – – Time Waveform Time Waveform Waveform useful for diagnosing bearing faults – Impacts show as spikes
- 23. ©2005, Emerson Process Management. Vibration – Bearing in FFT Vibration Vibration – – Bearing in FFT Bearing in FFT Bearing faults generate peaks at specific frequencies
- 24. ©2005, Emerson Process Management. An effective program... An effective program... An effective program... Choosing the transducer – the right one for the best data Signal processing – time waveform or spectrum Problem detection – examine both sets of data – is there a problem? Diagnosis – what is the source ? – Root Cause
- 25. ©2005, Emerson Process Management. Transducers Transducers Transducers Function – Convert mechanical signal to electrical Three basic types – Displacement transducer – Velocity transducer – Accelerometer
- 26. ©2005, Emerson Process Management. Displacement Transducers Displacement Transducers Displacement Transducers Advantages + – Measures relative movement – good for sleeve brg. machines – very good for heavy machines Disadvantages - – permanently installed – frequency response : DC to 1KHz – power required
- 27. Displacement probes act much like a transformer.
- 28. ©2005, Emerson Process Management. Velocity Transducer Velocity Transducer Velocity Transducer Connection Case Conductor Coil Spring Magnet Damper
- 29. ©2005, Emerson Process Management. Velocity Transducer Velocity Transducer Velocity Transducer Advantages + – best signal to severity ratio – good signal to noise ratio – no power required – single dif. / int. needed – usually pretty hardy Disadvantages - – usually big – heavy – freq. 10 to 2Kz – temperature sensitive – comparatively expensive – magnetic field sensitive – orientation sensitive – wear and temp. changes calibration
- 30. ©2005, Emerson Process Management. Accelerometers Accelerometers Accelerometers
- 31. ©2005, Emerson Process Management. Accelerometers Accelerometers Accelerometers Advantages – broad frequency range – small, light, rugged – ICP needs no signal conditioning – easy to mount Disadvantages – poor as a hand held – limited signal to noise ratio – reads acceleration – power required – double integration needed
- 32. ©2005, Emerson Process Management. Frequency Signature Frequency Signature Frequency Signature Frequency signal is an X,Y plot. X represents the frequency, Y represents the amplitude or magnitude of the signal. The data is divided into 3 categories : Synchronous – NxRPM where N is an integer (phase locked) Subsynchronous – <1 x RPM Non-synchronous – F x RPM where F is >1x RPM but not integer
- 33. ©2005, Emerson Process Management. Causes - Subsynchronous Causes Causes - - Subsynchronous Subsynchronous Another component in the machine Another machine Belt drives Hydraulic instability – Oil whirl, oil whip Rubs – rotor, shaft, wheel Cage – fundamental train - rolling element brgs.
- 34. ©2005, Emerson Process Management. Causes - Synchronous Causes Causes - - Synchronous Synchronous Imbalance Pitch line run-out Misalignment Bent shaft Looseness Blade / vane pass Reciprocals Gears Slot / Rotor Bar pass
- 35. ©2005, Emerson Process Management. Causes - Nonsynchronous Causes Causes - - Nonsynchronous Nonsynchronous Another machine Belt multiples Bearings Resonances Electrical Chains Compressor surge Detonation Sliding surfaces Lube pumps Centrifugal clutches U-joints