This is report of the experiment that we did in our engineering college in the subject of the instrumentation.

1. TITLE: - TO FIND THE SENSITIVITY OF THE LVDT
APPARATUS REQUIRED:-
1. DYNA-1750
2. Connecting Leads
3. Power Supply
4. Multimeter
THOERY:-
The linear variable differential transformer (LVDT) (also called linear variable
displacement transformer. linear variable displacement transducer, or simply differential
transformer}
is a type of electrical transformer used for measuring linear displacement (position).
A counterpart to this device that is used for measuring rotary displacement is called a rotary
variable differential transformer (RVDT).
The construction and circuit arrangement of an LVDT are as shown in Fig 6.1. It consists
of three coils mounted on a common former and having a magnetic core that is movable within
the coils.
The center coil is the primary and is supplied from an AC supply. The coils on either side
are secondary coils and are labeled A & B in Fig 6.1.Coils A & B have equal number of turns
and are connected in series opposing so that the output voltage is the difference between the
Voltages induced in the coils.
Movement of the core from its central (or neutral) position produces an output
voltage. This voltage increases with the movement from the neutral position to a maximum value
and then may reduce for further movement from this maximum setting. Note that the phase will
remain constant on either side of the neutral position. There is no gradual change of phase, only
an abrupt reversal when passing through the neutral position.
An amplitude only measurement of the output voltage, such as that provided by a meter, gives an
indication of movement from the neutral position but will not indicate the direction of that
movement. Used in conjunction with a phase detector, an output can be obtained that is
Dependent on both magnitude and direction of movement from neutral Position.

2. OBSERVATION AND CALCULATION
No. of rotation
In left
Output
voltage
No. of
rotation in
right
Output
voltage
1 0.012 1 0.010
2 0.019 2 0.017
3 0.026 3 0.025
4 0.030 4 0.032
5 0.0321 5 0.036
6 0.0321 6 0.039
7 0.0321 7 0.039
From Graph,
Residual Voltage=3mV
Then,
Sensitiviy(S)= 0.030-019
4.2
=5.5mV/rotation
RESULT AND CONCLUSION
Hence the sensitivity of LVDT was found to be 5.5mV/rotation.
0.039 0.039
0.036
0.032
0.025
0.017
0.01
0.006
0.012
0.019
0.026
0.03
0.03210.03210.0321
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
-10 -8 -6 -4 -2 0 2 4 6 8
Outputvoltages
No. of rotation in left and right
x-axis=>10 small division=1 pos
Y-axis=> 10 small division=0.004V