Industrial vibration sensors

This article deals with vibration transducers as a whole, vibration being the output quantity to be measured at any point on a vibrating object. The article deals only with mature technologies leading to robust devices with low sensitivity to external disturbances, applicable to industrial field measurements.

A vibration sensor is defined by: the quantity it measures (displacement, vibration velocity or acceleration), the measurement range expressed in absolute or relative level, the required accuracy and the environmental conditions.

In all cases, the sensor must be as "neutral" as possible. A sensor's fidelity is its ability to provide exactly the same response each time it is subjected to the same stimulus. To achieve this, it must be insensitive to temperature variations, to screwing and unscrewing on a baseplate, etc. It must also be highly stable, i.e. its sensitivity must not change as it ages, even in hostile environments (radiation, etc.), at least on the scale of periodic calibrations. It must be perfectly linear so as not to introduce harmonic distortion, i.e. have a transfer function that is as "flat" as possible over a wide frequency band and with a high measurement dynamic range, given the very high intrinsic dynamics of vibratory phenomena. It will have low crosstalk, whether with regard to ambient noise (low microphonic sensitivity), or the presence of vibrations in directions other than its measurement axis. It will be insensitive to the electromagnetic influences encountered in industrial environments, particularly near high-power generators and electric motors. Its optimization is both a measurement and a cost issue, which we won't go into here.

For special applications, suppliers can be asked to supply sensors matched much more closely than the average accuracy class.

The best sensor will only provide relevant indications if it is also implanted correctly, as explained in paragraph 8 .