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Interpretation of Linear Variable Differential Transformer (LVDT) voltage output

  1. Feb 5, 2013 #1
    Good day to all Physics Forums members,

    I am currently undertaking a project which involves the use of a Linear Variable Differential Transformer (LVDT) to measure the distance an object makes between two points. My setup is as follows:

    1. LVDT Type: Solartron DC50 with sensitivity of 6.158 mV/V/mm at 10 VDC
    2. Power supply to LVDT: 12.12 VDC (const. and cannot be varied)
    3. Voltage output from LVDT fed to dataTaker data acquisition system

    In an attempt at verifying the calibrated sensitivity of the LVDT, I performed a number of height measurements using gauge blocks. I took 6 equally-spaced height intervals between the maximums of the LVDT range and plotted the LVDT voltage output vs. height. Here is what I encountered:

    1. The curve plotted was NOT linear as I anticipated it to be. As a matter of fact, the curve fit a polynomial equation of degree five with R2 = 1
    2. When comparing the LVDT output voltage with the LVDT calibrated sensitivity values, discrepancies occured, e.g. a 20 mm difference between two gauge block heights returned a 20.5 mm difference calculated from the voltage output of the LVDT. The discrepancies grew as the ends of the LVDT were approached.

    My questions are:

    1. Could the fitted curve be beneficial for my use seeing as I've determined the end-to-end output values of the LVDT, OR,
    2. Should I, instead, just get the LVDT calibrated and use the obtained sensitivity value.

    To be frank, I would highly prefer Option 1, if it is in fact a justifiable solution.

    Any help is much appreciated. Thanks. :smile:
  2. jcsd
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