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Introduction to Peakvue

Introduction to Peakvue. Objectives. To Understand: 1. What Peakvue Is! 2. How it Works! 3. Filter Options Types of filters available Calculating the correct filter setting Filter Guidelines 4. Peakvue Data Spectrums and Waveforms Diagnosing Faults

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Introduction to Peakvue

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  1. Introduction to Peakvue

  2. Objectives • To Understand: • 1. What Peakvue Is! • 2. How it Works! • 3. Filter Options • Types of filters available • Calculating the correct filter setting • Filter Guidelines • 4. Peakvue Data • Spectrums and Waveforms • Diagnosing Faults • 5. Peakvue Versus Demodulation Techniques • 6. Acquiring Peakvue Data using the 2120A

  3. What is Peakvue™ • What is Peakvue? • Peakvue is a technology unique to CSI and means ‘Peak Value’ • Such as the Peak Value of an impact generated by a bearing defect in a time waveform - (True Peak Value) • If you have a 21XX analyzer you have the capability to acquire ‘Peakvue Data’ These stress waves travel further than conventional vibration signals so a truer indication of fault severity is obtained. • The ‘True Peak Value’ is obtained by concentrating on ‘Stress Wave Analysis’ rather than conventional vibration data.

  4. Initial Impact What is Peakvue™ What is a Stress Wave? • Stress waves accompany metal-metal impacting. These stress waves are short-term (fractional to a few milliseconds) transient events, which introduce a ripple effect on the surface machinery as they propagate away from the initial event. • If you think of a stone being dropped into a pool of water. The stone is the initial impact generated by the fault. The effect of the stone being dropped into the water cause a ripple on the surface of the water which, spreads over a wide area.

  5. What is Peakvue If a bearing has a sub-surface defect (early bearing wear), when a rolling element passes over the defect it bends the race slightly and then as the rolling element passes it restores back to it’s natural state. This event causes a high frequency (1-50KHz) short duration stress wave. This is what Peakvue detects

  6. How Does It Work? • A comparison can be made of the sampling to show how data is collected through both methods of data acquisition, normal and Peakvue™. Digital Peak Impact Detection FFT Vibration Signal High Pass Filter Full Wave Rectify

  7. How Does It Work? • The diagram below shows sampling of data using normal data collection. Stress wave- this is missed under normal conditions Instantaneous Samples

  8. Peakvue Samples How Does It Work? • The diagram below shows sampling of data using Peakvue™ data collection. Stress wave- this is missed under normal conditions

  9. How Does It Work? Peakvue measures the highest amplitude found in a stress waves (Pk Value) and holds that data • The waveform data is then passed through a high pass filter to remove the unwanted, low frequencies • Imbalance, Misalignment, Looseness, resonance etc. This just leaves us with the high frequency impacting data (Peak) above the machine noise level • The data is then brought back to fundamental frequency. (this allows analysis of the data to be done quicker and easier)

  10. Filters Types of filter available Filter Calculations Filter Guidelines

  11. Filters Options • There are two types of filter options in Peakvue, these are: • 1. Band Pass Filter • 2. High Pass Filter • Each of the filters are designed to remove unwanted data out of the signal at the appropriate levels • One of the key elements in acquiring meaningful peakvue data is the selection of ‘filters’ • Selecting the wrong type of filter will result in poor quality data • To much noise filtered through (the spectrum becomes very noisy) • To much is filtered out (The stress wave is not allowed to pass through)

  12. All low frequencies are removed from the input signal Stress Wave data is allowed to pass through the filter High Pass Filter Filter Options - ‘High Pass Filter’ • High Pass Filters remove all frequencies from the data below the filter setting but allow the high frequency stress wave to pass through.

  13. Data passes through filter Data is filtered out of the signal Data is filtered out of the signal Filter Options - ‘Band Pass Filters’ Looks for stress waves within a parameter defined by the filter setting. Frequencies above and below this setting are removed from the data

  14. Filter Selection • To select the correct filter we need to consider the highest operational defect frequency that we want to measure/detect. Then select the next available filter above that frequency • E.g. • Consider a typical motor / pump arrangement. We have: • 1 - 4 Pole A.C. Induction Motor • 2 - 3 Jaw Coupling • 3 - Centrifugal Pump • Typically the highest defect frequency to emit from this machine would be? • 1 - BPFI - Bearing Defect

  15. Filter Selection • 4 Pole Motor A.C Induction fitted with bearings SKF 6313 • Defect Frequencies (Orders) • FTF - 0.384 • BSF - 2.037 • BPFO - 3.071 • BPFI - 4.929 • Typically we would want to see the 10th Harmonic of the BPFI • Highest defect frequency: • (BPFI x 10) x Turning Speed (Hz) • (4.929 x 10) x 25 • 1232.3 Hz • We would then select the next available filter setting above the frequency

  16. High Pass Filters 500hz 1000hz 2000hz 5000hz 10000hz 20000hz Band Pass Filters 20hz – 150hz 50hz – 300hz 100hz – 600hz 500hz – 1khz Available filters From our previous calculation of 1232Hz, What filter setting would we select? Note: the meter will only allow you to select the next filter above the specified Fmax.

  17. Band Pass Filters 20hz – 150hz Felt problems on paper machines 50hz – 300hz Certain structural resonance excitation, modulation of gearmesh in low speed machinery 100hz – 600hz Gearmesh modulation in intermediate speed machinery. 500hz – 1khz Gearmesh modulation Filter uses (Band Pass) - Guidelines Tip: use bandpass filters when the event of interest is the excitation of a structural resonance, or the modulation of known frequencies – such as gearmesh.

  18. High Pass filters 500hz Low speed machinery having <125hz. Bearing & gearing problems 1000hz Intermediate speed machinery (<2000 rpm) with gear mesh <300hz 2000hz Medium speed machinery (<4000rpm) with gear mesh ,600hz 5000hz Machinery up to 9000rpm and gear mesh to 1500hz, Requires attention be paid to how the sensor is mounted as well as the sensors frequency response. 10000hz High speed machinery with gear mesh up to 3000hz sensor must be permanently mounted with a frequency response of 3db in the 30kHz or higher range. 20000hz High speed machinery with gearmesh up to 6000hz. Sensor must be high frequency and permanently mounted. Filter uses (Highpass) - guidelines Tip: Use highpass filters when the objective is to detect stress waves which are emitted by metal on metal impacting.

  19. Filter Selection - Question • Consider: • Motor running at a speed of 1000RPM • Driving a fan unit via pulley belts • Fan Speed is 1350RPM • Motor Bearings = SKF 3095 - BPFI 4.855 • Fan Bearings = SKF 6210 - BPFI 5.907 • Calculate what Filter setting would be required for both the motor and the fan bearings? • Filters Available: • 500 Hz, 1000Hz, 2000Hz, 5000Hz, 10000Hz, 20000Hz. (High Pass) • 20-150Hz, 50-300Hz, 100-600Hz, 500-1KHz. (Band Pass)

  20. Filter Selection - Answers Motor Speed = 1000CPM / 60 = 16.667Hz Fan Speed = 1350CPM / 60 = 22.5Hz • Filters Available: • 500 Hz, 1000Hz, 2000Hz, 5000Hz, 10000Hz, 20000Hz. (High Pass) • 20-150Hz, 50-300Hz, 100-600Hz, 500-1KHz. (Band Pass) • Motor. • BPFI = 4.855 • Defect Frequency = (BPFI x 10) x Turning Speed (Hz) • Defect Frequency = (4.855 x 10) x 16.667 • Defect Frequency = 809.18 Hz 1000Hz

  21. Filter Selection - Answers Motor Speed = 1000CPM / 60 = 16.667Hz Fan Speed = 1350CPM / 60 = 22.5Hz • Filters Available: • 500 Hz, 1000Hz, 2000Hz, 5000Hz, 10000Hz, 20000Hz. (High Pass) • 20-150Hz, 50-300Hz, 100-600Hz, 500-1KHz. (Band Pass) • Fan • BPFI = 5.907 • Defect Frequency = (BPFI x 10) x Turning Speed (Hz) • Defect Frequency = (5.907 x 10) x 22.5 • Defect Frequency = 1329.07Hz 2000Hz

  22. Peakvue Data Spectrums and Waveforms Diagnostics Techniques

  23. 1. Broad band energy - Filtered Noise 2. Units should be ‘acceleration’ (Very high frequency analysis) 3. Amplitude values are low. Severity of fault is not determined in the spectra Peakvue - Spectrum Here is a typical Peakvue spectra plot. This is typically a GOOD spectrum

  24. Notice the Impacts passing through the filtered noise 1. Broad band energy - Filtered Noise 2. Units still in ‘acceleration’ (Very high frequency analysis) 3. Amplitude values are low. Remember severity of fault is not determined in the spectra Peakvue - Spectrum This is a Peakvue spectrum where high frequency stress waves are being detected This is indication of a fault developing

  25. 1. Filtered Noise Level 2. Peak Value Impacts 4. Acceleration as default units 3. No Peak Negative Value Peakvue - Waveforms Waveforms can be confused with spectrums, as the waveform is only plotting the peak value and does not show a full wave.

  26. Peakvue - Diagnostics Diagnosing a Peakvue spectrum and waveform is not to dissimilar to that of conventional data. • However there are a few differences which can be a bit confusing at first, these are: • 1. Do not try to locate 1xTurning Speed, as this is low frequency data and will be filtered out. • Turning speed should be entered using the conventional spectral data. • 2. Multiple harmonics are often present within a spectrum due to the way peakvue samples the data. • These do not indicate ‘Looseness’ • 3. Spectral amplitudes are always low in amplitude but should not be used to judge severity. Use the spectrum to diagnose the fault. • 4. Waveforms indicate the severity of the problem.

  27. Peakvue - Diagnostics • Continued….. • 5. Ensure the same filter setting is used in both the spectrum and waveform. • Potential faults can be missed or overlooked if different filters are used. • 6. Cage Defects show up well in peakvue data and is normally an indication the bearing is under stress. • 7. All low frequency faults are removed from the data and will not be seen in a Peakvue spectrum and waveform • Imbalance, Misalignment, Looseness, Resonance - All Gone.

  28. 1.Spectral data indicating a defect at 5.463 Orders 3. Very Slow RPM 2. Impacting also being detected at 0.6G-s Peakvue - Diagnostics

  29. 4.Fault Frequencies Indicate a BPFI Defect Peakvue - Diagnostics

  30. Peakvue™ Amplitudes - Rolling Element Bearings • For machines running between speeds of 900 - 3600RPM recommended guidelines for setting initial warning levels in the Peakvue™ time - waveform are as follows:

  31. Peakvue™ Amplitudes - Rolling Element Bearings • For machines running at speeds <900RPM recommended guidelines for setting initial warning levels in the Peakvue™ time- waveform are as follows:

  32. Peakvue Vs Demodulation

  33. Less than 1ms Initial Impact Ringdown Peakvue Vs Demodulation • What is Demodulation? • This is a technique which concentrates on stress wave analysis, but is not as effective. • How Does it Work? • Demodulation looks for the ringdown that follows an impact, and tries to measure how quickly it fades. In order to do this the ‘Time Waveform’ has to be manipulated in such away that the waveform data becomes useless

  34. Demodulation registers Peak Impact Detection registers Peakvue Vs Demodulation • What are the Differences? • Peakvue samples the data much quicker enabling it to catch the very short duration high frequency stress wave. It then holds that ‘Peak Value’ throughout its parameter. • Due to the Analogue filtering system used by Demodulation, results in a ‘delay in response’ and the stress wave impact is missed

  35. Standard Demodulation A/D Converter FFT High Pass Filter Low Pass Filter Full Wave Rectify Remove DC Bias Enveloping Stage Peak Impact Detection Digital Peak Impact Detection FFT High Pass Filter Full Wave Rectify Peakvue Vs Demodulation The Process!

  36. Peakvue Vs Demodulation • Case Study. • Equipment • A conveyor system consisting of six rolls is driven by a motor/gearbox unit (GMU). • The motor speed is 1500RPM reduced through the gearbox giving the roller speed to be 98.5RPM

  37. Direct Comparison Between the Two Demodulation Spectra Peakvue Spectra Peakvue Demodulation Peakvue Vs Demodulation • Data was collected on each bearing of the conveyor system • Due to the slow speeds Peakvue and Demodulation Filters were both set to 500Hz High Pass using 1600 Lines of Resolution

  38. Demodulation Waveform Peakvue Waveform Peakvue Vs Demodulation

  39. Acquiring Peakvue Data Setting up the 2120A Creating a Peakvue AP Set

  40. Setting up the 2120A Peakvue can be accessed from the ‘Analysis Expert’ options found among the command keys of the 2120A • There are two ways of acquiring peakvue data within the 2120A • Bearing/Gear Analysis - Peakvue • Preset to acquire Peakvue data based upon the AP set assigned to the machine • User Setup Option • Allows user interface to define their own parameters

  41. Setting up the 2120A • User Set-up Option • Define the Fmax you wish to go to. Remember the Fmax is going to define your filter setting. • 0 - 30 KCPM = 500Hz High Pass • 30 - 60 KCPM = 1000Hz High Pass • 60 - 120 KCPM = 2000Hz High Pass • 120v - 300 KCPM = 5000Hz High Pass • Lines of Resolution • These have to be good enough to capture the FTF of a bearing, which would equate to around 15 Revolutions of waveform data. • Number of Revs = Number of lines / Fmax(Orders) • E.g. 800 Lines over an Fmax of 60 Orders = 13.3 Revolutions (Inadequate) • 1600 Lines over an Fmax of 60 Orders = 26.6 Revolutions (OK)

  42. Setting up the 2120A • Averages • This has to be set to 1 Average to gain the ‘true peak’ value. • If you start averaging the data then a stress wave detected in the first average that is not there in the second will lose it’s true amplitude when averaged together. • By using the ‘Page Down’ Button we can toggle through the pages until we find our Peakvue Options (Page 4 of 4) • We turn Peakvue to ‘Yes’ • The Pre-filter can now be changed to our required HP Setting • Units • The default unit for peakvue is ‘Acceleration’. Remember we are trying to detect very high frequency events, well above conventional vibration data. Acceleration accentuates high frequencies. • Sensor units can be used if using an accelerometer, however CSI recommend a minimum mounting of a ‘Rare Earth Magnet’ for data collection

  43. Setting up the 2120 • Data collection can now commence. • Check the data once collection has finished • Look for: • Impacts in both spectrum and waveform • Amplitude levels of the Waveform • quality of the data • If a problem is detected you may want to acquire more data with a different filter setting. • Remember to store the data once the reading has been taken • At least one Peakvue point should be applied to each critical machine to detect early bearing wear, gearwear or adverse metal to metal contact. • This will need building in the database and adding to the route

  44. Peakvue™ Analysis Parameter Setup Mastertrend and RBMware

  45. Peakvue™ AP Set up I • Open Database Management • Select Analysis Parameter

  46. Peakvue™ AP Set up II • Complete the spectrum setup, specifying Fmax, LOR and averages (1). • Specify the number of parameters - 2

  47. Peakvue™ AP Set up III • Check, ‘Use Analog pre-processor • Select Peakvue, under the ‘Envelope Demodulator’ • Select the filter setting.

  48. Peakvue™ AP Set up IV • Uncheck, ‘obtain special time waveform?’ - As Default units will be acceleration • Discard all settings when this is unchecked

  49. Peakvue™ AP Set up V • Complete Analysis Parameter specifications, the most important parameter is the ‘peak to peak’ waveform parameter. • Ensure ‘unit type’ is acceleration

  50. Gearbox case study

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