Capacitive transducers use the principle of a variable capacitor to measure physical quantities. They consist of two parallel metal plates separated by a dielectric material, where the distance between the plates can change. This allows the capacitance to vary depending on the measured quantity, such as level, torque, or displacement. Common types include changing the dielectric constant, plate area, or distance between plates. Capacitive transducers are sensitive, have high input impedance and require little output power, but require insulation and shielding from stray fields.

1. CAPACITIVE
TRANSDUCERS
DONE BY:
BALAGANESH.S (19L402)

2. INTRODUCTION
• The capacitive transducer or sensor is nothing but the capacitor with
variable capacitance.
• The capacitive transducer comprises of two parallel metal plates that
are separated dielectric material.
• the distance between the two plates is variable.

3. How is change measured?
• The change in capacitance can be measured easily and it is calibrated
against the input quantity
• Thus the value if the input quantity can be measured directly.

4. 1) Changing Dielectric Constant type
of Capacitive Transducers
• This principle is used for measurement of level in the hydrogen
container, where the change in level of hydrogen between the two
plates results in change of the dielectric constant of the capacitance
transducer.

5. 2) Changing Area of the Plates of Capacitive
Transducers
• This principle is used in the torquemeter, used for measurement of
the torque on the shaft.

6. 3) Changing Distance between the Plates of
Capacitive Transducers
• This is the most commonly used type of variable capacitance
transducer. For measurement of the displacement of the object, one
plate of the capacitance transducer is kept fixed, while the other is
connected to the object.

7. MICROPHONE LEVEL SENSOR

8. ADVANTAGES
• It requires an external force for operation and hence very useful for
small systems.
• The capacitive transducer is very sensitive.
• It gives good frequency response because of which it is used for the
dynamic study.
• The transducer has high input impedance hence they have a small
loading effect.
• It requires small output power for operation.

9. DISADVANTAGES
• The metallic parts of the transducers require insulation.
• The frame of the capacitor requires earthing for reducing the effect of
the stray magnetic field.
• Sometimes the transducer shows the nonlinear behaviours because
of the edge effect which is controlled by using the guard ring.
• The cable connecting across the transducer causes an error

10. THANKYOU
REFERENCES
• https://circuitglobe.com/capacitive-transducer.html
• http://www.instrumentationtoday.com/capacitive-transducers-
2/2011/07/