LOKNETE MA.

HANMANTRAO PATIL CHARITABLE TRUST’S

ADARSH INSTITUTE OF TECHNOLOGY
AND RESEARCH CENTRE, VITA
(NBA & NAAC Accredited Institute)

Engineering Wing / Polytechnic Wing

Department of Electrical Engineering

Class:-Second Year

Course:- Electrical and Electronic Measurement

Course Teacher:- Ms. P. P. Patil

 Department of Electrical Engineering (Course - Electrical and Electronic Measurement)

Polytechnic Wing

Vision

To become benchmark technical Institute where education is for next generation & everyone is
committed to delivering competent human resource for prosperity and well-being mankind.

Mission
To prepare competent engineers, technocrats and responsible citizens for engineering profession
through development of technical skills and create an environment that increases the involvement
and commitment of all stake holders for continuous improvement in performance and quality.

Program Outcomes (PO)

PO1. Basic and Discipline specific knowledge:

Apply knowledge of basic mathematics, science and engineering fundamentals and engineering
specialization to solve the engineering problems.
PO2. Problem Analysis:
Identify and analyse well-defined engineering problems using codified standard methods.
PO3. Design/ Development of Solutions:
Design solutions for well-defined technical problems and assist with the design of systems
components or processes to meet specified needs.
PO4. Engineering Tools, Experimentation and Testing:
Apply modern engineering tools and appropriate technique to conduct standard tests and
measurements.
PO5. Engineering Practices for Society, Sustainability and Environment:
Apply appropriate technology in context of society, sustainability, environment and ethical
practices.
PO6. Project Management:
Use engineering management principles individually, as a team member or a leader to manage
projects and effectively communicate about well- defined engineering activities.
PO7. Life Long Learning:
Ability to analyze individual needs and engage in updating in the context of technological changes.

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Engineering Wing
Vision
To be the benchmarked Institute of excellence in technical education and research, committed
to deliver competent human resource for prosperity and well being of the society.

Mission

 To impart the state of art technical education for generating engineers competent with
fundamentals, design, analysis and investigation approach capable of handling modern
tools.
 To inculcate strong ethical and moral values in students to work in team for environment
and sustainable development.
 To strengthen communication, management skills and continuous learning attitude in
young engineers dedicated for collaborative research for society through industry
interactions.

Program Outcomes (PO)

PO 1. Engineering Knowledge: Apply the knowledge of mathematics, science, engineering
fundamentals and an engineering specialization to the solution of complex engineering problems.
PO 2. Problem Analysis: Identify, formulate, research literature, and analyze complex engineering
problems reaching substantiated conclusions using first principles of mathematics, natural sciences
and engineering sciences.
PO 3. Design/Development of Solutions: Design solutions for complex engineering problems and
design system components or processes that meet the specified needs with appropriate consideration
for the public health and safety, and the cultural, societal, and environmental considerations.
PO 4. Conduct Investigations of Complex Problems: Use research-based knowledge and research
methods including design of experiments, analysis and interpretation of data, and synthesis of the
information to provide valid conclusions.
PO 5. Modern Tool Usage: Create, select, and apply appropriate techniques, resources, and modern
engineering and IT tools including prediction and modeling to complex engineering activities with
an understanding of the limitations.
PO 6. The Engineer and Society: Apply reasoning informed by the contextual knowledge to assess
societal, health, safety, legal and cultural issues and the consequent responsibilities relevant to the
professional engineering practice.
PO 7. Environment and Sustainability: Understand the impact of the professional engineering
solutions in societal and environmental contexts, and demonstrate the knowledge of, and need for
sustainable development.
PO 8. Ethics: Apply ethical principles and commit to professional ethics and responsibilities and
norms of the engineering practice.

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PO 9. Individual and Team Work: Function effectively as an individual, and as a member or

leader in diverse teams, and in multidisciplinary settings.
PO 10. Communication: Communicate effectively on complex engineering activities with the
engineering community and with society at large, such as, being able to comprehend and write
effective reports and design documentation, make effective presentations, and give and receive clear
instructions.
PO 11. Project Management and Finance: Demonstrate knowledge and understanding of the
engineering and management principles and apply these to one’s own work, as a member and leader
in a team, to manage projects and in multidisciplinary environments.
PO 12. Life Long Learning: Recognize the need for, and have the preparation and ability to engage
in independent and life-long learning in the broadest context of technological change.

Course Syllabus

Unit 1

Unit 2

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Unit 3

3.1 Digital measuring instruments-Essentials and advantages.

3.2 Construction and working of digital Meters-ammeter, Voltmeter and Multimeter,

Clamp-on meter, L-C-R meter, Power factor meter and Tachometer (Contact and Non-
contact).

3.3 Construction and working of Resistance measurement meters: Ohm meter, Digital
Megger, Digital earth tester.

3.4 Construction and working of meter used for synchronization: Frequency meter,
Synchroscope and Phase sequence indicator.

3.5 Function generator: Basic block diagram, function of each block and applications.

3.6 CRO: Basic block diagram, function of each block.

3.7 Digital storage Oscilloscope: Basic block diagram, function of each block.

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3.1 Digital measuring instruments-Essentials and advantages.

Essentials:-

Precision and Accuracy:- It should offer precise measurement and high accuracy.
Ease of reading:- Digital instruments display values directly on a numerical display, eliminating
the need to interpret needle positions.
Versatility:- Digital instruments can be programmed, store data, and connect remotely for
monitoring and control.

Compactness:- Digital instruments can be installed on a panel or DIN rail, and some models are
very compact

Advantages :-

Accuracy: Digital instruments are generally more accurate than analog instruments because they
have fewer moving parts.
Ease of use: Digital instruments are easy to read and free from parallax errors.
Calculations: Digital instruments can perform complex calculations and transfer data to a
computer.
Cost: Digital instruments are often less expensive than mechanical instruments.

3.2 Construction and working of digital Meters-ammeter, Voltmeter and Multimeter, Clamp-
on meter, L-C-R meter, Power factor meter and Tachometer (Contact and Non-contact).

Digital multimeter:-

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Measurement of Resistance −

In the resistance range, the Digital Multimeter operates by measuring the voltage across the
externally connected resistor, resulting from a current flowing through it from a calibrated internal
current source

Current Measurement

In DC Current Mode − The drop across an internal calibrated shunt is measured directly by the
Analog to Digital Converter (ADC).

In AC Current Mode − After AC to DC conversion, the drop across the internal calibrated shunt is
measured by the ADC.

Measurement of Voltage

AC Voltage Mode − The applied input voltage is fed through a calibrated, compensated attenuator,
to a full-wave rectifier followed by a ripple reduction filter. The resulting DC is fed to analog to
digital converter (ADC) and finally to the display system.

DC Voltage Mode - The applied input voltage directly fed to ADC to convert it into digital form.

Clamp on meter:-

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3.3 Construction and working of Resistance measurement meters: Ohm meter, Digital Megger,
Digital earth tester.

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3.4 Construction and working of meter used for synchronization: Frequency meter,
Synchroscope and Phase sequence indicator.

Frequency meter

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Amplifier: The signal whose frequency is to be measured is first amplified and supplied to the
schmitt trigger.

Schmitt Trigger: The schmitt trigger convert the signal into square wave having fast rise and fall
time.The square wave is then differentiated and clipped. Each pulse is proportional to each cycle of
unknown signal

Start – Stop gate: When the gate is open input pulses are allowed to pass through it.The counter is
now start counting the pulses. When gate is closed input pulses are not allowed to pass through
it.The counter is now stop counting the pulses.

Counter and display: The number of pulses during the period gate is open are counted by counter.If
the interval between start and stop condition is known the freuency of unknown signal is measured.

Synchroscope

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State and explain working of phase sequence indicator with suitable sketch.
Ans:
There are two types of phase sequence indicators and they are:
(a) Rotating type (b) Static type.
a) Rotating type

It Consists of three star connected coils mounted 1200 apart in space with three ends brought out and
marked R-Y-B as shown in figure.
An aluminum disc is mounted on the top of coils. The coils produce rotating magnetic field, when three
phase windings are energized by three phase supply.
Which sweeps the stationary aluminum disc and produces eddy emf induced in the disc which

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circulates an eddy current in aluminum disc.

Hence a torque is produced and disc revolves, the direction of rotation depends upon the phase
sequence of the supply.
If the direction of the rotations is same as that indicated by arrow head, the phase sequence of the supply
is same as the marked on the terminals.
However if the disc revolves in opposite direction indicated to arrow head, the sequence of the supply is
opposite to that marked on the terminals.
b) Static type.
Connect two lamps, lamp1 to R-phase, lamp2 to Y-phase and inductor to B-phase as shown in the
above figure.
Resistors are connected in series with the lamps for protecting the lamps from over currents and
breakdown voltages.
If the sequence of supply is RYB, then the lamp 2 will glow brighter than lamp 1; if the sequence of
the supply is reversed or altered, then the lamp 1 will glow brighter than the lamp

Unit 4 : Transducers and Pressure measurement

4.1 Instrumentation System-Block diagram, function of each block.

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4.2 Difference between sensors and transducer with examples.

4.3 Classification of transducer.

4.4 Electrical Transducers:

a) Resistive transducers- Linear and Angular potentiometers, strain gauge, load cell.

b) Capacitive transducer.

c) Inductive transducer –LVDT, RVDT.

4.5 Working of piezoelectric transducer, classification, examples.

4.6 Pressure measurement:

Pressure and its units, types - Absolute, Gauge, Atmospheric, Vacuum.

4.7 Classification of Pressure measuring devices.

4.8 Method of pressure measurement-

Bourdon tube with LVDT as secondary transducer

A transducer is an electronic device that converts signal from one form to another.

Common examples include microphones, loudspeakers, thermometers, position and pressure

sensors, and antenna.

4.1 Instrumentation system

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1. Primary Sensing Element:-

It is also known as "First Sensing Elements― The Element (Part) of an instrument which
makes first contact with the measure and is called the primary sensing element.
For example, In Ammeter (which is used to measure current), the coil carrying the current to be
measured is the primary sensing element

2. Variable conversion Element:-

The output of the Primary sensing element may not be suitable for the actual measurement
system.
A variable conversion element merely converts the output signal of the primary sensing
element into a more suitable variable or condition useful to the function of the instruments
Also keep in mind, that the original information about the measurand must be retained
during the process of such conversion.
2. Variable Manipulation Element:-
The level of the output from the Variable conversion element may not be enough for the next
stage
It manipulates the signal represented by some physical variable, to perform the intended task
of an instrument.
3. Data Transmission Element:-
If the elements of the system are physically separated, it is necessary to transmit the data from
one stage to the other. So we need this Data Transmission element
4. Data presentation Element:
It performs the translation function, such as present the data in a suitable form so that it is easily
understood by the observer and for this the Data Presentation Element is used

4.2 Difference between sensor and transducer.

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4.3 Classification of transducer

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Active and Passive Transducers

On the basis of the requirement of electricity, transducers are of two types:

o Active transducers operate on receiving an external electric current. This current is known
as an excitation signal. This signal is modified into an output signal. For example, an LED is
an active transducer because on receiving electrical current it converts the electrical energy
into light energy.
o Passive transducers operate on receiving an external signal, which they then convert into an
electrical signal. For example, an LVDT (Linear Variable Differential Transformer) converts
rectilinear motion into electrical energy.

Primary and Secondary Transducers

On the basis of the role of the transducing element, transducers are divided into:

o Primary transducers are generally the transducers that respond to external stimulation and
general output for that signal. The output is generally a change in any factor affecting the
secondary transducer.
o Secondary transducers are the ones that convert the output of the primary transducer into an
electrical signal.

Analog and Digital Transducers

Based on the output signal, transducers are classified into:

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o Analog transducers: These transducers produce an output signal that is proportional to the
input signal. Examples include potentiometers, variable resistors, and strain gauges.
o Digital transducers: These transducers produce an output signal that is in digital form.
Examples include encoders, photo-interrupters, and hall effect sensors

Transducer and inverse Transducer

Based on the conversion, transducers are classified into:

o Transducers: Converts a non-electrical quantity into an electrical quantity. Examples

include pressure gauges, strain gauges, photo-conductive cells, and therms-couples.
o Inverse transducers:Converts an electrical quantity into a non-electrical
quantity. Examples include piezoelectric crystals, transnational and angular moving-coil
elements, and ammeters or voltmeters.

Write one example of each type: (i) Active transducer (ii) Primary transducer. (iii) Electrical
transducer. (iv) Digital transducer.

(i) Active transducer:-Thermocouple, piezoelectric, photovoltaic cell

(ii) Primary transducer:- Bourdon tube, bellows,
(iii) Electrical transducer.:- LVDT,RVDT, Hall effect, strain gauge, ultrasonic
meter, optical pyrometer, radiation pyrometer
(iv) Digital transducer:- Linear Encoder, digital taco generator

4.4 Electrical Transducers:

a) Resistive transducers- 1) Linear and Angular potentiometers

Potentiometer is a passive component that works on moving the slider across the full length of the
conductor. The input supply voltage is applied to the entire length of the resistor. The output
voltage is measured as voltage drop between fixed and movable contact. The slider is adjusted
manually over the resistive strip to change the resistance value from zero to a higher value.When
the resistance changes, the current flowing through circuit changes. Hence according to Ohm‘s
law, the resistive material also changes.
Linear Potentiometer is a passive component that works on moving the slider across the full
length of the conductor.
Rotary potentiometer uses a rotational mechanism to alter the point of contact that exists between
the circular resistor and the wiper terminal

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2) Strain gauge

As we know that the resistance is directly dependent on the length and cross-sectional area of a
conductor, which is given by

R= ρL/A

Where,
‗R‘= Resistance

ρ = resistivity

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‗L‘ = Length

‗A‘ = cross-sectional area

Working :

functioning of a strain gauge entirely depends on the electrical resistivity of an object.

When an object gets stretched within its limits of elasticity and does not break permanently, it
becomes thinner and longer, resulting in high electrical resistance.
If an object is compressed and does not deform, but, broadens and shortens, results in decreased
electrical resistance. The values obtained after measuring the electrical resistance of a gauge helps
to understand the amount of stress-induced.

The excitation voltage is applied at the input terminals of a gauge, while the output is read at the
output terminals

Applications
 In the field of mechanical engineering development.
 To measure the stress generated by machinery.
 In the field of component testing of aircraft like; linkages, structural damage etc.

3) Load Cell

A load cell, also known as a force transducer or force sensor, works by converting a mechanical
force into an electrical signal. Strain gauge load cells: Use strain gauges to detect
measurements. The gauges are bonded to a beam or structural member that deforms when weight is
applied.

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The working principle of a load cell depends on the type of load cell, but generally involves the
following steps:

1. Deformation

When a force is applied to the load cell, the spring element or beam deforms slightly.

2. Strain gauge change

The deformation of the spring element or beam causes the shape of the strain gauges attached to it
to change.

3. Electrical signal

The change in the shape of the strain gauges is measured as a change in electrical signal.

b) Capacitive transducer.

The equations below express the capacitance between the plates of a capacitor Where A – overlapping area of
plates in m2
d – the distance between two plates in
meter
ε – permittivity of the medium in F/m

εr – relative permittivity
ε0 – the permittivity of free space
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

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capacitive transducer changes because of many reasons like overlapping of plates, change in
distance between the plates and dielectric constant.
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. As the distance between two plates is changes, value of capacitance is also changes.
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.

c) Inductive transducer – RVDT.

The design and construction of RVDT is similar to LVDT. The only difference is the shape of
the core in transformer windings. LVDT uses the soft iron core to measure the linear
displacement whereas RVDT uses the Cam-shaped core (Rotating core) for measuring the
angular displacement.
Case 1: When the core is at the Null position: When the core is at the null position then the
flux linkage with both the secondary windings will be the same. So the induced emf (Es1 and Es2
) in both the windings will be the same. Hence the Net differential output voltage E0= Es1 – Es2
will be zero (E0 = Es1 – Es2 = 0). It shows that no displacement of the core.
Case 2: When the core rotates in the clockwise direction: When the core of RVDT rotates in
the clockwise direction. Then, in this case, the flux linkage with S1 will be more as compared to
S2. This means the emf induced in S1 will be more than the induced emf in S2. Hence Es1 > Es2
and Net differential output voltage E0 = Es1 – Es2 will be positive. This means the output voltage
E0 will be in phase with the primary voltage.
Case 3: When the core rotates in the anti-clockwise direction: When the core of RVDT rotates
in the anti-clockwise direction. Then, in this case, the flux linkage with S2 will be more as
compared to S1. It means the emf induced in S2 will be more than the induced emf in S1. Hence

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Es1 < Es2 and Net differential output voltage E0 = Es1 – Es2 will be negative. This means the
output voltage E0 will be in phase opposition (180 degrees out of phase) with the primary voltage.
Applications

➢ Throttle lever position feedback

➢ Reeler / Dereeler
➢ Fuel Valves as well as Hydraulic
➢ Modern machine tools

LVDT

Working:-
An LVDT transducer comprises a coil former on to which three coils are wound.
The primary coil is excited with an AC current, and secondary coiil consist of two winding.
The excitation is applied to the primary winding and the armature assists the induction of
current in to secondary coils.
When the core is exactly at the center of the coil then the flux linked to both the secondary
winding will be equal. Due to equal flux linkage the secondary induced voltages (Vo1 &
Vo2) are equal but they have opposite polarities. Output voltage Vo is therefore zero.
This position is called ―null position‖
Now if the core is displaced from its null position toward sec1 then flux linked to sec1
increases and flux linked to sec2 decreases. Therefore Vo1 > Vo2 and the output voltage
of LVDT Vo will be positive
Similarly if the core is displaced toward sec2 then the Vo2 > Vo1 and the output voltage of
LVDT Vo will be negative

Applications

1. LVDT used to measure force

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2. LVDT used to measure strain

3. LVDT used to measure weight
4. LVDT used to measure tension
5. LVDT used to measure pressure

4.5 Working of piezoelectric transducer, classification, examples.

A piezoelectric transducer consists of quartz crystal which is made from silicon and oxygen
arranged in crystalline structure (SiO2).

When some mechanical pressure is applied across two faces of a quartz crystal, a voltage
proportional to the applied mechanical pressure appears across the crystal. Thus the potential
difference generated on the crystal due to its property.
Applied pressure causes change in physical dimension of crystal piece.

When a voltage is applied across the crystal surfaces, the crystal is distorted by an amount
proportional to the applied voltage. This phenomenon is known as the piezoelectric effect.

Application:

 They are used in seismographs to measure vibrations in rockets.

 In strain gauges to measure force, stress, vibrations etc
 Used by automotive industries to measure detonations in engines.

4.6 Pressure measurement: Pressure and its units, types - Absolute, Gauge, Atmospheric,
Vacuum.

Pressure is defined to be the amount of force exerted per area. P = F A ‍So to create a large amount
of pressure, you can either exert a large force or exert a force over a small area (or do both).

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• The following are units of Pressure

1. Pascals (Pa or N/m2)—N stands for newton which is SI unit of pressure
2. Psi - Pounds per square inch (PSI)
3. Bar – 105 Pascals
4. mm Hg-millimeters of Mercury 1mm of Hg = 1 Torr
5. Torr – 133.32 Pa
6. cm H2O – 1 cmH2O = 98.068 Pa1.
7.
➢ Atmospheric pressure (Barometric Pressure):-
It is defined as pressure exerted by the air surrounding to the earth .

➢ Gauge pressure
It is the pressure measured with the help of pressure measuring instrument’ in which
atmospheric temperature is taken as datum

➢ Absolute pressure
It is defined as total pressure including atmospheric pressure acting on a surface area

Atmospheric pressure + Gauge Pressure

➢ Vacuum pressure
It is the pressure below the atmospheric pressure.

Atmospheric pressure - Gauge pressure

4.7 Classification of Pressure measuring devices.

Classification of Pressure measuring devices

1) Non elastic Pressure transducer/manometer
U Tube manometer
Well type manometer
Inclined type manometer
Barometer
2) Elastic Pressure Transducer/Mechanical
Bourdon tube
Bellows
Diaphragms
Capsule
3) Electronics Pressure Transducer
Inductive type :Bourdon tube with LVDT

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Diaphragms with Strain Gauge(Resistive)

Capacitive Pressure Transducer
Piezoelectric Pressure Transducer
4) Measurement of vacuum
McLeod gauge
Thermal conductivity gauge
Pirani gauge
Thermocouple gauge

4.8 Method of pressure measurement-

Bourdon tube with LVDT as secondary transducer

The pressure measurement using bourdon tube and LVDT is shown in the figure.
In this, the bourdon tube act as primary transducer and LVDT which follows the output of bourdon
tube act as a secondary transducer.
The bourdon tube senses the pressure and converts it into a displacement.
The free end of bourdon tube shows this displacement.
A cord is used to connect the free end of bourdon tube to the core of LVDT as shown in figure.
When the free end shows the displacement, the core of LVDT also moves.
This movement of core is proportional to the displacement of free end, which is proportional to the
applied pressure.
The LVDT gives analogues output which is a conversion of displacement into respective.

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Unit - V Flow, Level and Temperature Measurement

5.1 Flow measurement -Flow and its units,
classification of flow transducers -Variable head flow meter, Variable area flow meter.
5.2 Methods of measurement of electrical flow meter:
a) Electromagnetic Flow meter. b) Ultrasonic flow meter.
5.3 Level measurement-Level and its units classification of level measurement
transducer Resistive, Inductive and Capacitive.
5.4 Method level measurement: Capacitive, Ultrasonic and Radiation.
5.5 Temperature Measurement-Temperature and its Units, classification-Thermistors,
Resistance Temperature Detector (RTD) and Thermocouple.
5.6 Methods of temperature measurement- RTD and thermocouple.

5.1 Flow measurement -Flow and its units

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Flow means to move along stream as water does. Flow also means to circulate, as air does. Flow is
used as a noun to mean movement as if in a stream. Flow has several other senses as a verb and a
noun. When something flows, it moves like water in a stream.

Umits of Flow:-
Mass flow rate
The SI unit for mass flow rate is kilograms per second (kg/s). However, other units are often
used, such as ton/h or kg/h.
Volumetric flow rate
The SI unit for volumetric flow rate is cubic meters per second (m3/s). Other units include:
1. Standard cubic centimeters per minute (SCCM)
2. Cubic feet per second (ft3/s)
3. Gallons per minute (gpm)
4. Liters per second (L/s)

Define.

Laminar flow:-

When all the molecules of flow are parallel to each other, it is called Laminar flow.

Turbulent flow: -

The flow in which fluid flows in zig-zag manner and fluctuate irregularly in such a way that its velocity
changes irregularly, such type of flow is known as turbulent flow.

classification of flow transducers -Variable head flow meter, Variable area flow meter.

Orifice Plate meter:

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An Orifice Meter is basically a type of differential flow meter which is used to measure the rate of fluid flow
(mainly Liquids or Gases), using the Differential Pressure Measurement principle.

The orifice plate is being fixed at a section of the pipe, creates an obstruction to the flow by providing an
opening in the form of an orifice to the flow passage. Flow of any fluid passage through the plate.

Working :-

The fluid flows inside the Inlet section of the Orifice meter having a pressure P1.

As the fluid proceeds further into the Converging section, its pressure reduces gradually and it finally reaches
a value of P2 at the end of the Converging section and enters the cylindrical section.

The differential pressure sensor connected between the Inlet and the the Cylindrical Throat section of the
Orifice meter displays the difference in pressure (P1-P2).

This differential pressure is measured using U tube manometer is in direct proportion to the flow rate of the
liquid flowing through the Orifice meter.

Applications :-

 Refineries
 Water treatment plants,
 Natural gas processing plants
 Petrochemical plants
 Oil filtration plants

Venturimeter:-

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Working :-

It is a primary element of differential pressure Flow meters.

1) It consists of a straight inlet section, a converging conical inlet section, a cylindrical throat and diverging
recovery cone.

2) Straight inlet section has same diameter as pipe. In converging conical inlet

section, the cross-section of stream decreases & velocity increases.

3) In cylindrical throat, flow velocity will be maximum & static pressure will be minimum.

4) In diverging recovery cone flow velocity decreases

5) The pressure taps are located at straight edge section and at cylindrical throat where pressure is minimum
thus the maximum Pressure Gauges across this point.

6) As it has no sharp edges and does not project into fluid stream, it can be used to handle fluids with solid,
slurries, etc.

7) The cross-sectional area of fluid does not increase or decreases abruptly, so permanent pressure loss or
energy loss is very low as compared to orifice plate.

Applications:-

The most common uses for venturi meters are as follows:

 Used to monitor airflow in engine carburetors (automotive industry).

 Measures and controls process flow in process industries (Process and Power Piping Industries).

 Venturi Meters are used to monitor blood flow in the arteries in the medical field.

Rotameter:-

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• It consists of a vertical tube with conical cone or shape.

• It is constant pressure drop variable flow meter in which float is free to move within it the fluid
flows through the tube from bottom to the top
• When no fluid is flowing the float reset at the bottom of the tube
• The float is made of such a diameter that it completely blocks the inlet section

• When a flow starts in a pipeline and the fluid reaches the float, the buoyancy effect of fluid makes
the float lighter.
• The float has a density greater than that of flowing material so that the buoyancy effect alone is not
sufficient to lift the float. The float remains close until the pressure of flowing material (fluid flow or
Drag) + buoyancy effect of fluid exceeds the downward pressure due to the weight of the flow. The
float then rises and floats within the flowing medium (Pipe) in proportional to the flow rate
• The float reaches a stable position in the tube when the upward force exerted by the flowing fluid
equals the downward gravitational force exerted by the weight of the float.
• Increase in the flow rate causes the float to rise higher in the tube.Decrease in the flow rate causes
the float come down to the lower level
• The float gives reading on a calibrated scale and the flow rate can be determined.
Applications:-

Chemical, petrochemical, and pharmaceutical industries: Rotameters are used in high pressure
applications to measure aggressive, opaque, and non-conductive fluids.
Medical applications: Rotameters are used to measure oxygen flow in anesthesia systems and
hospital gas lines.
5.2 Methods of measurement of electrical flow meter:

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 Department of Electrical Engineering (Course - Electrical and Electronic Measurement)

a) Electromagnetic Flow meter.

Ultransonic flow meter

It operates either by the absorption of acoustic energy as it travels from source to receiver or by
attenuation (frequency change) of a vibrating diaphragm face, oscillating at 35 to 40 KHz.

It operates by generating ultrasonic pulse and measuring the time it takes for the echo to return.
When an ultrasonic transmitter is mounted at top of the tank, the pulse travels in air at speed of 331
m/s at 0 0C.

The time of travel is an indication of depth of vapor space above the liquid in the tank. If ultrasonic
transmitter is mounted on bottom of tank, time of travel reflects the depth of liquid in tank and speed
of travel is function of what the liquid is. For water at 25 0C, an ultrasonic pulse travel at speed of
1496 m/s.

5.6 Methods of temperature measurement- RTD and thermocouple.

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 Department of Electrical Engineering (Course - Electrical and Electronic Measurement)

Thermocouple.

 A thermocouple is made up of two dissimilar metals, joined together at one end, that produce a
voltage (expressed in millivolts) with a change in temperature. The junction of the two metals,
called the sensing junction, is connected to extension wires. Any two dissimilar metals may be
used to make a thermocouple.
 A thermocouple works on the principle of the Seebeck effect, which states that when two
different metals are joined at one end and exposed to a temperature difference, an electromotive
force (EMF) is generated.
 If one of two junctions heated then current flows in the circuit can be detected by meter.
 Two junctions are shown junction p and q with their temperature T1 and T2.
See back Effect: When a pair of dissimilar metals are joined at one end (junction, J1) , and there is a
temperature difference between the joined ends and the open ends ( junction , J2 ), thermo-emf is
generated, which can be measured in the open ends ( J2 or cold junction).
Peltier Effect: The Peltier effect is a temperature difference created by applying a voltage between
two dis-similar metals connected to a sample of semiconductor material.

RTD

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Department of Electrical Engineering (Course - Electrical and Electronic Measurement)

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 Department of Electrical Engineering (Course - Electrical and Electronic Measurement)

Courses offered at AITRC

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Polytechnic Wing Course

(Under MSBTE Board) Code
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(Under DBATU University) Code
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 Department of Electrical Engineering (Course - Electrical and Electronic Measurement)

Artificial Intelligence & Machine Learning Engineering 11921

Electronics & Telecommunication Engineering 11372
Electrical & Computer Engineering 11926
Mechanical Engineering 11612
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