Tuesday, February 3, 2013

To:                                Professor  Larson
From:                           Joe Average, Jane Random, John Doe
Subject:                        Laboratory Exercise 3, “Linear Variable Differential Transformer”
Date of Experiment:   January 27, 2013

In this experiment, a Sangamo model AE11 linear variable differential transformer (LVDT) was tested to determine the relationship between output voltage and core displacement.  A Hewlett-Packard model HP8648A multi-function synthesizer provided the A/C voltage input source, and also supplied the trigger signal for a Tektronix 220DS digitizing oscilloscope used to display results. The phase angle between the A/C excitation voltage and the output signal was also found by examining the time delay between LVDT input and output signals.

With the LVDT core at the null position, the output voltage was measured at a level of 4.8 milli-volts RMS. An approximately linear relationship between core displacement and output voltage was noted for core displacements up to +/- 18 mm from the null position. A 180.0° output signal phase angle shift occurred as the core was translated through the null position, as predicted by LVDT theory. Sensitivity of the unit tested was found to be 41.6 mV/V*mm, within 5 % of manufacturer’s specifications. 

A power surge and subsequent power failure for a few minutes during the first attempt at running the experiment resulted in a complete loss of data: The experiment was repeated and consistent results were obtained. These results were then used for the calculations that appear in this report. 

Additional information including graphical results, the test apparatus used, raw data gathered, and sample calculations illustrating the data reduction methods used are attached.



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