LUTRON VT8204
The vibration sensor supplied with the VT8204 is a piezo-electric accelerometer
and is widely used in industry for machine vibration measurement.
Principles of operation:
Please refer diagram below. An electrical output is produced by the
accelerometer when the piezo-electric element is squeezed between the seismic
mass and the base. In basic terms – when the accelerometer is moved vertically
in an up and down motion the piezo-electric material compresses/extracts and
experiences a force, in turn it generates an electric charge between its surfaces.
This electric charge is proportional to the amount of acceleration/deceleration the
unit experiences. For those wishing to educate themselves further on the
fundamentals of this type of accelerometers please refer to attachment
Accelerometer.pdf (please keep in mind this is a generalized document not
specific to the Lutron sensor).
The electrical signal produced by the accelerometer is digitized in the hand held meter
and can now be used to display acceleration levels on the LCD display. In the case of
the VT8204 we view this in either “g” or “m/s²” when using the metric scale, 1g being the
equivalent to 9.81m/s ². With the understanding the sensor is an accelerometer and can
only produce an output due to acceleration/deceleration one might ask how does the
meter display velocity and displacement? This function is carried out by the process of
differentiation, the meters internal microprocessor calculates both velocity and
displacement by using the measured acceleration and the frequency the sensor is
oscillating at. Differentiation involves a multiplication by frequency, this means the
vibration acceleration at any frequency is proportional to the velocity times the
