31-01-2013, 04:14 PM
CAPACITIVE TRANSDUCER
[attachment=49135]
What is capacitive transducer?
Capacitive transducers are nothing but the capacitors with the variable capacitance. These are mainly used for the measurement of displacement, pressure etc. It is a Passive type of Transducer.
Principle of Operation:
The capacitive transducers works on the familiar capacitance equation of parallel plate capacitor, which is given by:
Where,
C is the capacitance of the capacitor
εo is the absolute permittivity
εr is the relative permittivity
A is the area of the plates
d is the distance between the plates
The product of εo & εr is also called as the dielectric constant of the capacitive transducer.
Construction and working:
The capacitive transducer comprises of two parallel metal plates that are separated by the material such as air, which is called the dielectric material. In the typical capacitor, the distance between the two plates is kept varying. In the instruments using capacitance transducers the value of the capacitance changes due to the change in the value of the input quantity that is to be measured. This change in capacitance can be measured easily and it is calibrated against the input quantity, thus the value of the input quantity can be measured directly.
Capacitance of the Capacitive Transducers
The capacitance C between the two plates of capacitive transducersis given
Where,
C is the capacitance of the capacitor
εo is the absolute permittivity
εr is the relative permittivity
A is the area of the plates
d is the distance between the plates
The product of εo & εr is also called as the dielectric constant of the capacitive transducer.
Now from the equation, we get to know that the capacitance of capacitive transducer depends on the area of the plates and the distance between the plates and it also changes with the change in the dielectric constant of the dielectric material used in it.
CAPACITIVE THICKNESS TRANSDUCER
Thickness of a thin insulating sheet such as glass mica, paper and Bakelite can be measured by capacitive transducer. The plates can be so arranged that the sheet, which is under continuous production, may be passed in between the plates without them.
[attachment=49135]
What is capacitive transducer?
Capacitive transducers are nothing but the capacitors with the variable capacitance. These are mainly used for the measurement of displacement, pressure etc. It is a Passive type of Transducer.
Principle of Operation:
The capacitive transducers works on the familiar capacitance equation of parallel plate capacitor, which is given by:
Where,
C is the capacitance of the capacitor
εo is the absolute permittivity
εr is the relative permittivity
A is the area of the plates
d is the distance between the plates
The product of εo & εr is also called as the dielectric constant of the capacitive transducer.
Construction and working:
The capacitive transducer comprises of two parallel metal plates that are separated by the material such as air, which is called the dielectric material. In the typical capacitor, the distance between the two plates is kept varying. In the instruments using capacitance transducers the value of the capacitance changes due to the change in the value of the input quantity that is to be measured. This change in capacitance can be measured easily and it is calibrated against the input quantity, thus the value of the input quantity can be measured directly.
Capacitance of the Capacitive Transducers
The capacitance C between the two plates of capacitive transducersis given
Where,
C is the capacitance of the capacitor
εo is the absolute permittivity
εr is the relative permittivity
A is the area of the plates
d is the distance between the plates
The product of εo & εr is also called as the dielectric constant of the capacitive transducer.
Now from the equation, we get to know that the capacitance of capacitive transducer depends on the area of the plates and the distance between the plates and it also changes with the change in the dielectric constant of the dielectric material used in it.
CAPACITIVE THICKNESS TRANSDUCER
Thickness of a thin insulating sheet such as glass mica, paper and Bakelite can be measured by capacitive transducer. The plates can be so arranged that the sheet, which is under continuous production, may be passed in between the plates without them.