TE - White Papers

TE CONNECTIVITY SENSORS / WHITE PAPER Predictive Maintenance with Vibration Sensors PAGE 2 Driven by increased automation, demand is rising on high-volume, smaller systems such as machine spindles, conveyor belts, sorting tables, or machine tools which require better predictive maintenance. Machine downtime in these applications is a critical consideration in terms of customer experience and profitability. In the past, accelerometers were primarily used for condition monitoring of heavy, high end machinery such as windmills, industrial pumps, compressors and HVAC systems. However, we see an increasing demand for high volume and smaller machinery, driven by digital industrial transformation. This white paper will compare different technologies of accelerometers in industrial condition monitoring. CRITICAL FACTORS For industrial condition monitoring and predictive maintenance applications the following vibration specification parameters are considered critical to ensure long-term, reliable, stable and accurate performance. • Wide Frequency Response • Measurement Resolution and Dynamic Range • Long-Term Stability with Minimum Drift • Operating Temperature Range • Packaging Options and Ease of Installation • Sensor Output Options Wide Frequency Response In order to detect all possible failure modes of machinery, the frequency response of the accelerometer should be 40 to 50 times the shaft RPM (Revolutions Per Minute) for bearing monitoring. For fans and gearboxes, the minimum upper limit of the accelerometer should be 4 to 5 times the blade passing frequency. The lower frequency limit is less critical, depending on machinery; rarely is a frequency <2Hz required. Measurement Resolution and Dynamic Range The measurement resolution of the vibration sensor is a function of the amplitude of the output signal to the broadband noise of the onboard electronics. An accelerometer with superior signal output will allow the measurement of smaller vibration levels in the machinery. The ability to measure lower vibration amplitude enables the end user to predict a fault much earlier than a sensor with a lower dynamic range. There are other factors that will influence the measurement resolution such environmental conditions, EMI/RFI (Electromagnetic and Radio Frequency) Interference, DAQ (Define Data Acquisition) interface, and cable length so all factors need to be considered for the chosen installation As a general rule, the output signal should be 10x higher than the noise level of the sensor for the output to be a reliable measurement. A simple equation for measurement resolution is as follows; RESOLUTION (g's) = BROADBAND NOISE (V) / SENSOR SENSITIVITY (V/g)

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