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Performance of the measurements
To perform the measurement, you have to set, according to your needs, the following parameters:
The input gain (Menu >> Settings >> General >> Measures >> Input Gain): you can set the greatest value but this should not lead to overload, as shown below.
The Integration Delay (Menu >> Settings >> General >> Measures >> Integration Delay). Delaying the integration beginning, allows stabilizing the signal and obtaining a more repeatable measurement. Usually 5 seconds are enough.
The Integration Interval (Menu >> Settings >> General >> Measures >> Integration Interval) can be used as a timer to automatically stop the measurement when the set time has elapsed. When set to zero, you can stop the measurement only manually.
The measurement duration is selected to represent the person's exposure to vibrations. To change the duration of the measurement interval, you can also press ENTER from the standard VLM page, until the "Tint" symbol is blinking. Then modify its value and confirm with ENTER.
To start the recording, press REC and START/STOP simultaneously.
At the end of the integration interval Tint, the instrument stops the measurement and prompts you to save the data: press SAVE.
The data saved in the memory can be downloaded to the PC using the NoiseStudio software (please see later in this guide).
The polarization voltage of the accelerometers
Before performing the measurements, you have to check the accelerometers' polarization voltages. To do so, you only need to put the instrument in measurement mode, Menu >> Settings >> General >> System and check the polarization voltages Vpol of the 4 measurement channels. The correct polarization voltage is indicated by the accelerometer manufacturer and is normally between 8V and 12V.
A wrong polarization voltage could mean that the connection cable between the accelerometer and the instrument is faulty, or that there are contact problems between accelerometer, connection cable and analyzer.
Determination of the input gain
To determine the input gain correct value, you can perform a test measurement.
From an input gain of 20dB, you can perform a test measurement for a sufficient time to obtain a measurement representative of the characteristics of the tool being assessed.
If you do not see any overload indication, proceed with measurement. Otherwise, reduce the gain of 10dB and repeat the test.
If the overload indication remains, set a 0dB input gain.
If you still detect an overload, you should replace the accelerometer with one having a lower sensitivity.
Selection of the integration interval
The integration interval is set according to the trend of the vibrations being assessed.
If the vibrations remain constant, you may need few seconds to get a stable and repeatable measurement. On the contrary, if the vibrations vary cyclically or according to the type of disturbance, you need an integration time of many cycles, to get repeatable measurements. Alternatively, you can sample each cycle, using short integration intervals, and calculate the average value by keeping in mind the total duration.
Later you will see some examples of typical measurements that you can actually encounter.
To display the acquired measurements, you should install the NoiseStudio software and then download the data.
If the software is not installed, click on this link: go to NoiseStudio installation.
If the NoiseStudio software is installed, and the download to the PC has been performed, you can display the results.
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