Unit 5.pptx electrical and electronics measurement
1. Ashokrao Mane Group of
Institutions
Vathar Tarf Vadgaon
Department of Electrical Engineering
Subject: Electrical and Electronic Measurements
Mr. R. S. Pukale
Assistant Professor
Unit:5 Transducer
2. Transducer
• Definition: The device which converts the one form of energy into another is
known as the transducer.
• The process of conversion is known as transduction.
• The conversion is done by sensing and transducing the physical quantities like
temperature, pressure, sound, etc.
4. Active and Passive Transducer
Active Transducer
These transducers do not need an external source of power to operate. Therefore, they are also
called self-generating type transducers.
Examples:
• Piezo-electric,
• Photovoltaic,
• Piezoelectric,
• Electromagnetic
5. Passive Transducer
Passive Transducer
The transducers need an external source of power for their operation.
• So they are not self-generating type transducers.
Examples:
• Resistive,
• Inductive,
• Capacitive transducers.
6. Analog and Digital Transducer
The transducer can also be classified by their output signals. The output
signal of the transducer may be continuous or discrete.
• Analog Transducer – The Analog transducer changes the input quantity
into a continuous function. The strain gauge, L.V.D.T, thermocouple, and
thermistor are examples of analogue transducers.
• Digital Transducer – These transducers convert an input quantity into a
digital signal or in the form of a pulse. The digital signals work on high or
low power.
7. Primary and Secondary Transducers
• Primary Transducer – The transducer consists the mechanical as well
as the electrical devices. The mechanical devices of the transducer
change the physical input quantities into a mechanical signal. This
mechanical device is known as the primary transducers.
• Secondary Transducer – The secondary transducer converts the
mechanical signal into an electrical signal. The magnitude of the output
signal depends on the input mechanical signal.
10. • Consider the Bourdon’s Tube shown in the figure below. The tube act as a
primary transducer. It detects the pressure and converts it into a displacement
from its free end. The displacement of the free ends moves the core of the linear
variable displacement transformer. The movement of the core induces the output
voltage which is directly proportional to the displacement of the tube free end.
• Thus, the two type of transduction occurs in the Bourdon’s tube. First, the
pressure is converted into a displacement and then it is converted into the
voltage by the help of the L.V.D.T
• The Bourdon’s Tube is the primary transducer, and the L.V.D.T is called the
secondary transducer.
11. Transducer and Inverse Transducer
Transducer – The device that converts the non-electrical quantity into an
electric quantity is called the transducer.
Inverse Transducer – The transducer that converts the electric quantity into a
physical quantity; such type of transducer is known as the inverse transducer.
The transducer has high electrical input and low non-electrical output.
12. Based on Transduction
• The transducer is classified by the transduction medium.
The transduction medium may be resistive, inductive, or
capacitive, depending on the conversion process by
which the input transducer converts the input signal into
resistance, inductance, and capacitance, respectively.
14. Construction of LVDT
• The transformer and LVDT share a similar construction. It consists of one
primary winding(P) and two secondary windings (S1 & S2). The primary and
secondary windings are bounded by a hollow cylinder, known as the former.
The primary winding is at the center and the secondary windings are
present on both sides of the primary winding at an equal distance from the
center. Both the secondary windings have an equal no. of terms and they
are linked with each other in series opposition, i.e. they are wounded in
opposite directions, but are connected in series with each other.
• The entire coil assembly remains stationary during distance measurement.
The moving part of the LVDT is an arm made of magnetic material.
15. Working Principle of LVDT
• The working of LVDT is based on Faraday's law of electromagnetic induction,
which states that "the electrical power in the network induction circuit is
proportional to the rate of change of magnetic flux in the circuit."
• As the primary winding of LVDT is connected to the AC power supply, The
alternating magnetic field is produced in the primary winding, which results in
the induced EMF of secondary windings.
• Let's assume that the induced voltages in the secondary windings S1 & S2 are
E1 & E2 respectively. Now , according tousing, the rate of change of magnetic
flux, i.e. dΦ/dt, is directly proportional to the magnitude of induced EMF, i.e
E1 and E2.
• The total output voltage Eo in the circuit is given by Eo = E1-E2
• Depending on the position of the core some cases arise:
16. Case 1: When The Core is Moving Towards S1
When the core of LVDT moves towards the second winding S1 , the flux linkage S will be greater than that of S2. The EMF
induced in S1 will be more than the EMF of S2. Hence, E1 is greater than E & net differential voltage Eo(E1-E2) will be +ve.
The means output voltage Vo will be in phase with input AC voltage.
Case 2 : When the core is positioned at its null position
When the core is at a null position then the flux generated in both the secondary windings will be the same. The induced
EMF E1 & E2, and both the windings will be the same. Hence the net differential output voltage Eo will be 0. It shows 0
displacement of the core.
Case 3 : When The Core Moving Towards S2
When the core of LVDT moves towards secondary winding S2, the flux linkage with S2 will be more than S1. It means the EMF
induced in S2 will be more than the induced EMF of S1 Hence E2 is greater than E1 & net differential voltage Eo (E1-E2) will
be negative. It means the output voltage will be out of phase input AC voltage.
18. • Display the displacement versus output voltage graph for both left
and right movement and how the output voltage varies with linear
displacement.
• The LVDT is an electromechanical device that generates an AC voltage
output in direct proportion to the ferromagnetic core and relative
displacement of the transformer. The ability of LVDT sensors to
function in harsh environments with high levels of vibration and shock
is a crucial feature.
19. • Advantages of LVDT
• High output: For minute variations in the magnetic core position, LVDTs provide a
high output.
• Low hysteresis: LVDTs are highly repeatable due to their extremely low hysteresis.
• Low electrical noise: Because LVDTs have sensing coils with low impedance, they
can produce extremely low electrical noise levels.
• Less power Consumption: LVDT's consume less power as compared to other
Transducer’s
• Disadvantages of LVDT
• Since LVDT is an inductive transducer it is sensitive to the stray magnetic field,
hence an extra setup is required to protect from stray magnetic field.
• As LVDT is an electromagnetic device, it is also affected by vibrations and
temperature.
20. Applications of LVDT
• It is mostly used in industries in the field of Automation, Aircraft, Turbines,
Satellite, Hydraulics etc.
• LVDT is used to measure physical quantity such as force, tension, pressure
weight, etc. here LVDT is used as a secondary transducer.
• LVDT plays important role in geotechnical Instrumentations, as it is used for
Monitoring Ground Movements, Landslides and Structural Stability
• LVDT plays an important role in the marine and offshore industry by
Monitoring the Movements and Positions of ships and Underwater
Structures.
• LVDT Plays an important role in Power Generation as it monitors the Critical
Components in turbines and generators.
21. Rotary Variable Differential Transformer (RVDT)
• Definition: The transformer which senses the angular displacement
of the conductor is known as the Rotary Variable Differential
Transformer or RVDT.
• it is the type of electromechanical transducer that gives the linear
output proportional to the input angular displacement.
23. Displays and Recorders
Classification of Recorder
• Graphic Recorder
• X-Y Recorder
• Strip Chart Recorder
• Circular Chart Recorder
• Galvanometric type Recorder
• Potentiometer type Recorders
• Magnetic Tape Recorder
• Digital Recorders
• Printer and Plotter
25. X-Y Recorder
• X-Y recorders are used to plot one variable with respect to another
variable.
27. Applications
Engineering and Research
1. I-V Characteristics:
1. Used to study current vs. voltage relationships in electronic components.
2. Stress-Strain Analysis:
1. Records the deformation behaviour of materials under mechanical stress.
Industrial Testing
3. Control Systems:
1. Analyzes feedback signals in automation and control systems.
4. Quality Assurance:
1. Monitors relationships like pressure vs. flow or temperature vs. time in manufacturing processes.
Scientific Studies
5. Thermodynamics:
1. Studies pressure-volume or temperature-entropy relationships in systems.
6. Physics Experiments:
1. Plot relationships like force vs. displacement or magnetic flux vs. current.
30. Application
• Medical Applications
• Electrocardiograms (ECG):
• Continuously records heart activity on paper for diagnostic purposes.
• Temperature Monitoring:
• Records patient body temperature variations in hospitals.
• Industrial Applications
• Process Monitoring:
• Tracks parameters such as temperature, pressure, and flow rate in industries like chemical,
petrochemical, and food processing.
• Power Plants:
• Records operational parameters like boiler temperature, steam pressure, and turbine speed.
31. Environmental Monitoring
• Weather Stations:
• Logs temperature, humidity, and atmospheric pressure changes over time.
• Pollution Monitoring:
• Records pollutant concentrations in air or water samples.
Laboratory and Research
• Scientific Experiments:
• Monitors parameters like voltage, current, and pH in experiments.
• Material Testing:
• Records stress-strain curves during material testing
33. Application
• Industrial Applications
• Process Monitoring:
• Used in industries like oil and gas, chemical, and food processing to track
temperature, pressure, or flow.
• Boiler Operations:
• Monitors boiler pressure and temperature in power plants.
