Lutron Electronics vt8204 User Manual

Piezo-electric accelerometer

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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

Table of Contents

Do you have a question about the vt8204 and is the answer not in the manual?

Page 1 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...
Page 2 frequency. It is a similar result for displacement - the vibration velocity at any frequency is proportional to the displacement times of the frequency. For a given displacement, if the frequency is doubled, the velocity will also double and if the frequency is increased tenfold, the velocity is also increased by a factor of ten.
Page 3 Summary If velocity and displacement is of particular interest then use at frequencies above 10 Hz is desirable). During handling/mounting of the sensor for low frequency (below 10Hz), movement of the sensor/cable will affect the meter readings and they should not be considered accurate. Lutron state a Frequency Range of 10Hz to 1kHz and a calibration point of 160Hz in the specification area of the manual.
Page 4 It is best to keep the Anchorage loop of cable as Point short as allowable...