Lutron Electronics vt-8204 User manual

Brand: Lutron Electronics

Model: vt-8204

Type: User manual

Lutron Electronics VT-8204 Vibration Meter The VT-8204 Vibration Meter is a handheld device that measures vibration levels in machines and structures. It is used for a variety of purposes, including predictive maintenance, troubleshooting, and quality control. The VT-8204 has a wide frequency range of 10 Hz to 1 kHz and can measure acceleration, velocity, and displacement. It also has a built-in data logger that can store up to 100 readings. The VT-8204 is a valuable tool for anyone who needs to measure vibration levels. It is easy to use and provides accurate and reliable readings.

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

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.

To add further clarity, if the sensor produces a constant force of 1g at varying

frequencies we can easily see the relationship to velocity and displacement.

Frequency Acceleration Velocity Displacement

(Hz)

(g) (mm/s) (mm)

1000 1 1.56 0.00025

100 1 15.6 0.025

10 1 156 2.5

1 1 1560 250

*All above readings in peak

Notes from Lutron

The vibration sensor and the vibration cable are the very high impedance units,

so the vibration measurement procedures should be executed very carefully.

During the measurement, hand or the fingers cannot touch the cable or the

socket, only use the hand to hold the instrument if necessary [much better to

clamp in place]

For the precision vibration measurement, if possible, we should use tape to fix

the cable on a solid place to prevent it from moving

The above operation procedures should be consideration for the displacement

measurement especially because the displacement circuit is the high gain

compared with the measurement of acceleration and velocity

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. We recommend to have the

anchor point of the cable on the fixture that is being measured (as per following

page). This will allow the cable to move in the same motion as the sensor – and

forces on the sensor and cable will now have a better chance of staying equal,

this is more critical at lower frequencies

Anchorage

Point

It is best to keep the

loop of cable as

short as allowable

Lutron Electronics vt-8204 User manual

Brand: Lutron Electronics

Model: vt-8204

Type: User manual

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Lutron Electronics vt-8204 User manual

Lutron Electronics vt-8204 User manual

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