2. FUNCATION
An LVDT Displacement Transducer have 3 coils ; a primary
and two secondary's.
The transfer of current between the primary and the
secondary's of the LVDT displacement transducer is
controlled by the position of a magnetic core called an
armature.
On our position measurement LVDTs, the two transducer
secondary's are connected in opposition.
At the centre of the position measurement stroke, the two
secondary voltages of the displacement transducer are
equal but because they are connected in opposition the
resulting output from the sensor is zero.
3. As the LVDTs armature moves away from centre, the
result is an increase in one of the position sensor
secondary's and a decrease in the other. This results in
an output from the measurement sensor.
With LVDTs, the phase of the output (compared with
the excitation phase) enables the electronics to know
which half of the coil the armature is in.
The strength of the LVDT sensor's principle is that
there is no electrical contact across the transducer
position sensing element which for the user of the
sensor means clean data, infinite resolution and a very
long life.
Our range of signal conditioning electronics for LVDTs
handles all of the above so that you get an output of
voltage, current or serial data proportional to the
measurement position of the displacement transducer.
5. MATHEMATICAL EQUATION
Transformer
The basic transformer formula, which states that the
voltage is proportional to the number of coil windings,
is the backbone of the LVDT. The formula is,
Vout/Vin=Nout/Nin
where N is the number of coil windings and V is the
voltage read out.
This equation is,
D=MVout
where D is displacement of the iron core with respect to
the transformer, and M is the sensitivity of the
transformer (slope of the displacement-voltage curve).
6. .
Ratiometric Wiring LVDTAnother commonly used LVDT
wiring is known as ratiometric wiring, as shown
schematically below.
Ratiometric Wiring
The displacement for ratiometric LVDT's is given by the
relation,
D=M * VA-VB/VA+VB
Used
Mostly as a sensor in different field
