Sensors and Transducer

IV SEMESTER

ETIC-203

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Potentiometer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Potentiometer

• Potentiometer :It is defined as a three-terminal resistor having either sliding or rotating contact that forms an adjustable voltage divider. In order to use the potentiometer as a rheostat or variable resistor, it should have only two terminals with one end and the wiper.

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Potentiometer working principle

The potentiometer consists of L which is a long resistive wire and a battery of known EMF V whose voltage is known as driver cell voltage. Assume a primary circuit arrangement by connecting the two ends of L to the battery terminals. One end of the primary circuit is connected to the cell whose EMF E is to be measured and the other end is connected to galvanometer G. This circuit is assumed to be a secondary circuit.

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Properties of Potentiometer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Construction of Linear Potentiometer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Ckt Diagram

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Mathematical Description

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Mathematical Description

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Strain gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Term used in Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Term used in Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Theory of Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Theory of Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Theory of Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Theory of Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Advantages and Disadvantages

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Ideal Material for Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Types of Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Types of Strain Gauge

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Inductive Sensors

• An inductive sensor is a device that uses the principle of electromagnetic induction to detect or measure objects. An inductor develops a magnetic field when a current flows through it; alternatively, a current will flow through a circuit containing an inductor when the magnetic field through it changes. This effect can be used to detect metallic objects that interact with a magnetic field. Non-metallic substances such as liquids or some kinds of dirt do not interact with the magnetic field, so an inductive sensor can operate in wet or dirty conditions

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Terms in Inductive Sensors

Simple Inductance

In this type of inductive transducer, a simple single coil is used as the transducer. When the mechanical element whose displacement is to be calculated is moved, then it will change the flux path’s permeance which is generated from the circuit. It modifies the inductance of the circuit as well as the equivalent output. The circuit o/p can be directly adjusted against the input value. Therefore, directly it provides the parameter’s valve to be calculated.

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Terms in Inductive Sensors

Two-Coil Mutual Inductance

• In this type of transducer, there are two different coils are arranged. In the primary coil, the excitation can be generated with external power source whereas in the next coil the output can be attained. Both the mechanical input as well as output are proportional.

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Inductive Transducer Working Principle

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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The working principle of an inductive transducer is the magnetic material’s induction. Just like the electrical conductor’s resistance, it depends on various factors. The magnetic material’s induction can depend on different variables like the twists of the coil over the material, the magnetic material’s size, & he flux’s permeability.

Inductive Sensor Ckt Diagram

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Principle of Inductive sensor

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Principle of Inductive sensor

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Basic Principle of Inductive sensor

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Eddy Current Production

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Transformer Type Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Principle

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer(sensors)�

Definition: The capacitive transducer is used for measuring the displacement, pressure and other physical quantities. It is a passive transducer that means it requires external power for operation. The capacitive transducer works on the principle of variable capacitances. The capacitance of the capacitive transducer changes because of many reasons like overlapping of plates, change in distance between the plates and dielectric constant.

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The capacitive transducer contains two parallel metal plates. These plates are separated by the dielectric medium which is either air, material, gas or liquid. In the normal capacitor the distance between the plates are fixed, but in capacitive transducer the distance between them are varied.

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

• The capacitive transducer contains two parallel metal plates. These plates are separated by the dielectric medium which is either air, material, gas or liquid. In the normal capacitor the distance between the plates are fixed, but in capacitive transducer the distance between them are varied.
• The capacitive transducer uses the electrical quantity of capacitance for converting the mechanical movement into an electrical signal. The input quantity causes the change of the capacitance which is directly measured by the capacitive transducer.

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• The capacitors measure both the static and dynamic changes. The displacement is also measured directly by connecting the measurable devices to the movable plate of the capacitor. It works on with both the contacting and non-contacting modes

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Principle of Operation

The equations below express the capacitance between the plates of a capacitor

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Where A – overlapping area of plates in m²�d – the distance between two plates in meter�ε – permittivity of the medium in F/m�ε_r – relative permittivity�ε₀ – the permittivity of free space

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Principle of Operation

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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The schematic diagram of a parallel plate capacitive transducer is shown in the figure below. 

Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducers

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Capacitive Transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Application Of Capacitive transducer

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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The capacitive transducer is mainly used for measurement of linear displacement. The capacitive transducer uses the following three effects.

• Variation in capacitance of transducer is because of the overlapping of capacitor plates.
• The change in capacitance is because of the change in distances between the plates.
• The capacitance changes because of dielectric constant.

Advantage of Capacitive Transducer�

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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The following are the major advantages of capacitive transducers.

• 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.

Disadvantages of capacitive Transducer�

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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The main disadvantages of the transducer are as follows.

• 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 behaviors because of the edge effect which is controlled by using the guard ring.
• The cable connecting across the transducer causes an error.

Uses of Capacitive Transducer�

Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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The following are the uses of capacitive transducer.

1. The capacitive transducer uses for measurement of both the linear and angular displacement. It is extremely sensitive and used for the measurement of very small distance.
2. It is used for the measurement of the force and pressures. The force or pressure, which is to be measured is first converted into a displacement, and then the displacement changes the capacitances of the transducer.
3. It is used as a pressure transducer in some cases, where the dielectric constant of the transducer changes with the pressure.

Uses of Capacitive Transducer

4. It is used as a pressure transducer in some cases, where the dielectric constant of the transducer changes with the pressure.
5. The humidity in gases is measured through the capacitive transducer.
6. The transducer uses the mechanical modifier for measuring the volume, density, weight etc.

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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Department of Electrical and Electronics Engineering, BVCOE New Delhi Subject: Sensor and Transducer , Instructor: Ritambhra Katoch

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