Measurement of Displacement using LVDT

Apparatus Required

Introduction

L.V.D.T. stands for Linear Variable Differential Transformer .It is basically a mutual inductance type transducer with variable coupling between the primary and the two secondary coils. It is equivalent to E pick- off in its operation except the reluctance of the magnetic path is mostly due to the air path. It consist of a primary coil, uniformly wound over a certain length of transducer and two identical secondary coils systematically wound on either side of the primary coil and away from the center . The iron core is free to move inside the coil in either direction from null position. When the primary coil is excited by an A.C supply the induced EME of the secondary are equal to each other with the case lying in null position. The two secondaries are connected in series, but in phase opposition so that the resultant output voltage is zero. Displacement of the core in either direction from the null point results in output voltage proportional to displacement but have opposite polarity. The output voltage as read by an A.C. RMS voltmeter and is observed that

Diagram of LVDT

Observation Table:

Precautions

1. To get the good performance from the tutor you take to maintain room temperature.
2. To check the power source it should be 230 volt + 10%, 50 Hz to avoid over voltage hazardous.
3. To get best performance you take to put the instrument at dust proof and humidity free environment.
4. Do not try to open the instrument or repair it contact manufacture in case of any fault/difficulty.

Viva-Voice Questions and Answers

1. What is the full form of LVDT?
2. What is the Principal of LVDT?
3. What is the Advantages & Disadvantages of LVDT?
4. What is the application of LVDT?