An LVDT consists of a primary winding, two secondary windings on a hollow cylindrical former, and a movable core. The secondary windings have an equal number of turns connected in series to oppose each other's induced EMFs. The position of the core determines the flux linkage between the AC-excited primary and secondary windings. When the core moves from the center, more flux links one secondary coil than the other, producing an output voltage proportional to the direction and amount of core movement. The LVDT's output voltage varies linearly with core position within its range of motion.

1. CONSTRUCTION AND WORKING OF LVDT

2. ◎ LVDT - LINEAR VARIABLE DIFFERENTIAL
TRANSDUCER
◎ The linear variable differential transducer consists of
◎ P1 – One Primary winding.
◎ S1 and S2- Two Secondary winding on Hollow cylindrical former.
◎ The secondaries have an equal number of turns connected in series.
◎ The emf induced in the coil oppose each other.
◎ The Primary winding connected to an AC source.
◎ Frequency range 50Hz to 20kHz.

3. ◎ Position of the movable core determine
the flux linkage between the a.c excited
primary winding and secondary
winding.
◎ Core made up of nickel-iron to reduce
eddy current losses
◎ The core in Centre the induced emfs in
the secondaries are equal and they
oppose each other the output voltage
will be zero volt.

4. ◎ When an extremely applied force moves
the core to the left-hand position more
magnetic flux links the left-hand coil than
the right-hand coil.
◎ Es1 – left-hand coil
◎ Es2 - right-hand coil
◎ The emf of induced in the Es1 is larger
than Es2
◎ When the core is forced to move to the
right more flux links the right hand coil
than the left-hand coil.

5. ◎ LVDT output voltage is a function of the core position.
◎ The amount of a voltage change in either secondary winding is proportional
to the amount of movement of the core.
◎ By noting which output is increasing or decreasing the direction is
determined.
◎ The core moves from the Centre the greater difference in value between Es1
and Es2and consequently greater the output.
◎ The amount of output voltage of an LVDT is an linear function of the core
display within a limited range of motion.

6. THANK YOU