Electrical measurements are the methods, devices and calculations used to measure electrical quantities. Measurement of electrical quantities may be done to measure electrical parameters of a system. Electrical measurements are a branch of the science of meteorology. Learn and Enjoy.

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Electrical Measurement, Instrumentation and
Sensors
Course outline:
 Magnetic Measurement: Ballistic Test, Measurement of Flux
density, B-H curve, Testing of BarSpeciment, Permeameters:
Double Bar, Burrows, Fuhy's.R, L, C measurement :
 Transducers (Optical): Photometry and Radiometry,
Photoconductive Sensors Fritz Schuermeyer and Thad
Pickenpaugh, Photojunction Sensors, Charge-Coupled
DevicesMeasuring instruments :
 Temperature Measurement: Bimaterials Thermometers,
Resistive Thermometers, Thermistor Thermometers,
Thermocouple Thermometers, Semiconductor Junction
Thermometers Infrared Thermometers, Manometric
Thermometers, Temperature Indicators, Fiber-Optic Ther-
mometers, Thermal Imaging.

2.  Flow Measurement: Di_erential Pressure Flowmeters,
Variable Area Flowmeters, Positive Dis-placement
Flowmeters, Turbine and Vane Flowmeters, Impeller
Flowmeters
 Electromagnetic Flowmeters, Ultrasonic Flowmeters,
Thermal Mass Flow Sensors, Drag Force Flowmeters
 Level Strain and Torque Measurement
 DC and AC signal conditioning: basic elements, A/D and D/A
converters, Sample and Hold circuits.
 DC and AC signal conditioning: basic elements, A/D and D/A
converters, Sample and Hold circuits.
 Function generation and linearization, Noise and its sources
and Noise elimination, Op-Amp review, Instrumentation
amplifier
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3.  Data Transmission and Telemetry: Methods of data
transmission, dc and ac telemeter system
 Digital data transmission.
 Recording devices:
 Display devices:
 Data Acquisition system
 Microprocessor application in instrumentation
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4. Books
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5. Books
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(III) GOLDINGS

6. CH-1:Measurements & measurement system
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Measurement : It is a process of
converting physical parameters in
meaningful numerical numbers.
Example : Your friend is suffering from
fever. Now you ask “How is your fever ?”
He replies “Very high”. This does not
involve any measurement. But if he
replies “My temperature is 102 0 ” then it
is a meaningful number and it gives
more clear idea of his fever.

7. Methods of measurement :
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Direct method: In these methods, the unknown
quantity is directly compared against a standard.
Example : Measurement of physical quantities like length, mass
and time etc.
Indirect methods: Measurement of direct methods are
not always possible ,feasible and practicable. So we
need of indirect methods of measurement……….

8. Instrument
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A device for determining the value or magnitude of a quantity or
variable.
Example : A thermometer is required to measure the temperature
of a human body.
 Three phases of instruments are:
Mechanical instruments: these are very reliable for static and
stable conditions but unable to respond rapidly to measurement of
dynamic and transient condition.
Electrical instruments: more rapidly than mechanical .
Ex : galvanometer, ….
Electronic instruments: These instruments require use of
semiconductor devices. The only movement involved is that of
electrons, the response time is extremely small .
Ex : CRO

9. Classification of Instrument:
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 (i) Absolute instruments : these instruments give the
magnitude of the quantity under measurement in terms
of physical constants of the instrument. Ex: tangent
galvanometer.
(ii) Secondary instruments: These are so constructed
that the quantity being measured can only be measured
by observing the output indicating by the instruments.
Ex: voltmeter, thermometer…..
Function of instruments & measurement system:
(i) Indicating function
(ii) Recording function
(iii) Controlling function
Application of measurement system: your work…

10. Accuracy
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A1
10v
1
A2
9 A
9.5 A
ohm
How the instrument reading is close
to the actual quantity.
Example : Suppose you want to find the
weight of a chicken purchased from market.
The shopkeeper takes the weight by his
“Daripalla” to be 1kg and 100 gram. But if
you take the weight with a balance in your
Laboratory, you may find it to be 1.1053 kg,
which is more closer to the actual quantity.

11. Precision
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10
5
3
2
1
Megaohm
2957358
ohm
It is the degree to which successive measurements
differ from each other.

12. Sensitivity
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100
150
200
100
200
400
V
V
Ratio of the response of the
instrument to a change of the
input signal.
Example : Suppose two
voltmeters are used to
measure the voltage of the
same circuit. Now the circuit
is slightly changed so that the
voltage is also changed by a
small quantity. The pointer of
one meter moves by small
distance, whereas the pointer
of the other meter moves by
a larger distance. Therefore
the second meter is more
sensitive.

13. Resolution
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1
2
3
4
5
Voltmeter
1
2
3
4
5
Voltmeter
The smallest change in the
instrument reading to which it can
respond.
Example : Suppose you purchase a
fish. The fisherman has a “Daripalla”
and “Butkhara”, the minimum size of
the butkhara which he has is 100 gm.
So the weight of your fish will be
either 800gm or 900gm or 1000gm
etc.

14. Error
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Error
Gross
Error
Systematic
Error
Random
Error
Deviation from the true value of the quantity
measured.
All errors may be classified into three different
types.

15. Gross Error
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10
20
30
40
50
Voltmeter
10X0
100v
10k
10k
V
R=10k
Human error
Misreading of
Instrument
Incorrect adjustment
Improper application
Computational
mistakes

16. Systematic Error
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Instrumental error
•Frictional loss
•Irregular spring
tension
•Overloading
•Permanent Stress
•More…..
Environmental error
•Dusty environment
•Temperature change
•Humidity
•Electromagnetic field
•More…..

17. Random Error
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Error due to unknown causes even all
precautions and preventive measures are
observed.
Example : Suppose a voltmeter is used to
monitor the voltage of a circuit at an interval of 1
hour. Sometimes it is observed that the meter
reading includes small amount of deviations in
each reading, even if all cautions are taken.

18. Elimination of Error
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Minimization of Gross error :
Be more careful while taking
reading.
Minimization of Random
error :
Increase the number of
reading and apply statistical
analysis.
Minimization of Systematic
error :
•Take care of your measuring
Instrument.
•Ensure proper environment.
Errors can not be eliminated totally. However it can
be minimized by observing proper corrective steps.

19. Ammeter
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Is = I – Im
Rs = Im Rm / Is
Ammeter
10v
1
10 A
ohm

20. Voltmeter
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100v
1
1
ohm
ohm
Voltmeter

21. Magnetic Measurement
Principle Requirement for Magnetic Measurements are:
 Measurement of magnetic strength in air
 The Determination of B-H curve and Hysteresis loop for
the soft ferromagnetic materials
 Determination of Eddy Current and Hysteresis losses
 Testing of Permanent Magnet
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22. Types of Tests
 Ballistic Tests
 A.C. Testing
 Steady State Test
Ballistic Tests: These Test are generally employed
for the determination of B-H Curve and
Hysteresis loop
A.C Testing: These are Carried out at power,
audio or radio frequencies
Steady State Test: These are performed to obtain
the steady value of flux density existing in the air
gap of a magnetic circuit
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23. Measurement of flux density
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26. B-H Curve
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27.  When initially magnetised, the curve follows
points a–b on the graph, but on reducing H to zero,
some residual magnetism remains (point c - also
known as the remanent flux density). In order to
fully demagnetise the specimen, it is necessary to
apply a negative magnetic field strength (point d -
called the coercive force). Making H increasingly
negative leads to negative saturation (point e).
If H is reduced back to zero, point f is reached
(negative residual magnetism). As H becomes
positive, the flux density reduces to zero (point g)
and then becomes positive, finally returning back
to point b (positive saturation), after which the
cycle b–g repeats.
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28.  The area enclosed by the B-H curve (shaded
light blue above) is proportional to the energy
loss as the ferromagnetic material is
magnetised with varying polarity by connection
to an alternating (AC) power supply. This energy
loss is undesirable and causes unwanted heating
of the material. In general, harder
ferromagnetic materials have higher hysteresis
losses, since more energy is required to realign
the magnetic domains
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29. Determination of B-H Curve
Two methods:
 Methods of Reversal
 Step by Step Method
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30. Methods of Reversal
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31. Step by Step Method
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33. Determination of Hysteresis
loop
 Step By Step Method
 Method of Reversal
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34. Testing Of Bar Specimen
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Permeameter

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38. Ewing Double Bar Permeameter
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41. Burrow’s Permeameter
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