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Reply to "Low Speed Bearing Analysis - What is possible?"

What is the OEM and model of the digital accelerometer that you have?

You can compare some of the critical specifications of the digital accelerometer to piezoelectric accelerometer such as this one:

Typical Piezoelectric Accelerometer with ICP power

CTC AC203 Series Low & High Frequency Accelerometer

AC203 Datasheet (ctconline.com)

Sensitivity: 100 mv/g

Frequency Response: (+/- 3 dB) 6-600,000 cpm or 0.1-10,000 Hz

Dynamic Range: +/- 80 g

Spectra Noise in micro g per square root Hz: 1.3 @ 10 Hz, 0.2 @ 100 Hz, 0.1 @1000 Hz

Temperature Range: -58 to 250 F (50 to 121 C)

Resonant Frequency: 18,000 Hz

Mounting: 1/4-28 stud for tapped hole or with adhesive mounting disk

The digital accelerometer has one third the sensitivity, and it has over 800 times more noise spectral density than the piezoelectric accelerometer. The digital accelerometer has a lower temperature limit. The piezoelectric accelerometer is superior in many specifications.

Bearing fault detection for a shaft at 6 rpm can be a real challenge for the following reasons:

  1. It may only be possible to detect a significant bearing fault rather than an early warning of a developing fault.
  2. Low frequency and amplitude acceleration values for bearing fault frequencies.
  3. Bearing vibrations may not be detectable with high vibrations from accelerometer noise and from other machine components or other machines.
  4. A long measurement time of 5 to 10 revolutions is needed which would be 50 to 100 seconds of data per measurement. The vibration analyzer must have long time record measurement capability.
  5. Vibration signal analysis capability should include overall peak acceleration level, time waveform, FFT spectrum, and demodulated (envelope or PeakVue) spectrum.
  6. An accurate shaft speed measurement that may require multiple pulses per revolution.

Here is some additional information:

Low Speed Bearing Fault Detection

Search: bearing vibrations on low speed shafts

bearing vibrations on low speed shafts - Bing

Low Speed Bearing Analysis

ABSTRACT: (vibration.org)

Low Speed Bearing Analysis – Vibration Institute (vi-institute.org) purchase of same article?

Low Speed Trunnion Bearing Problems -- good setup information

Microsoft PowerPoint - P2 Low Speed Trunnion Bearing Problems (rms-reliability.com)

Condition monitoring of low-speed bearings - A review

From <https://www.researchgate.net/p..._bearings_-_A_review>

An Overview of Bearing Vibration Analysis

Vibration brochure (final art) (schaeffler.com)

Slow speed bearing defect detected though vibration analysis

From <https://theseasonedanalyst.gur...-vibration-analysis/>

Low-speed bearing monitoring Challenges and Solutions

PowerPoint Presentation (bearing-news.com) by SKF

Walt

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