lecture1.ppt instrumentation and sensors

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1. LECTURE 1: INTRODUCTION
Kamlesh T. Kahar
Faculty of Elect. & Telecommunication Engineering
SSGMCE

2. Instrumentation
◦It is the branch of engineering that deals with
measurement & control of process variables within a
production/manufacturing area.
Measurement
◦A method to obtain information regarding the
physical values of the variable.
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3. Physical quantity: variable such as pressure,
temperature, mass, length, etc.
Data: Information obtained from the
instrumentation/measurement system as a result of
the measurements made of the physical quantities
Information: Data that has a calibrated numeric
relationship to the physical quantity.
Parameter: Physical quantity within defined
(numeric) limits.
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4. 4
measurand Sensor, signal conditioning, displayMan, tracking control etc

5. Measurand: Physical quantity being measured.
Calibration: Implies that there is a numeric
relationship throughout the whole instrumentation
system and that it is directly related to an approved
national or international standard.
Test instrumentation: It is a branch of
instrumentation and most closely associated with the
task of gathering data during various development
phases encountered in engineering, e.g. flight test
instrumentation for testing and approving aircraft.
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Terminology

6. Transducer: A device that converts one form of
energy to another.
Electronic transducer: It has an input or output that is
electrical in nature (e.g., voltage, current or
resistance).
Sensor: Electronic transducer that converts physical
quantity into an electrical signal.
Actuator: Electronic transducer that converts
electrical energy into mechanical energy.
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7. In the case of process industries and
industrial manufacturing…
◦To improve the quality of the product
◦To improve the efficiency of production
◦To maintain the proper operation.
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8. To acquire data or information (hence data
acquisition) about parameters, in terms of:
◦putting the numerical values to the physical
quantities
◦making measurements otherwise inaccessible.
◦producing data agreeable to analysis (mostly in
electrical form)
Data Acquisition Software (DAS) – data is
acquired by the instrumentation system.
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9. Direct comparison
◦Easy to do but… less accurate
e.g. to measure a steel bar
Indirect comparison
◦Calibrated system; consists of several devices to
convert, process (amplification or filtering) and
display the output
e.g. to measure force from strain gages located in a
structure
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10. Stage 1: A detection-transducer or sensor-transducer, stage; e.g.
Bourdon tube
Stage 2: A signal conditioning stage; e.g. gearing, filters, bridges
Stage 3: A terminating or readout-recording stage; e.g. printers,
oscilloscope
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General Structure of Measuring System

11. Passive Instruments
◦the quantity being measured simply modulates (adapts to)
the magnitude of some external power source.
Active Instruments
◦the instrument output is entirely produced by the quantity
being measured
Difference between active & passive instruments is the level of
measurement resolution that can be obtained.
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12. e.g. Float-type petrol tank level indicator
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13. The change in petrol level moves a potentiometer
arm, and the output signal consists of a proportion of
the meter reading which varies according to the
position of float.
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14. e.g. Pressure-measuring device
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15. The pressure of the fluid is translated into a
movement of a pointer against scale.
The energy expanded in moving the pointer
is derived entirely from the change in
pressure measured: there are no other
energy inputs to the system.
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16. An analogue instrument gives an output that
varies continuously as the quantity being
measured; e.g. Deflection-type of pressure
gauge
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17. A digital instrument has an output that varies
in discrete steps and only have a finite
number of values; e.g. Revolution counter
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18. Home
◦Thermometer
◦Barometer
◦Watch
Road vehicles         
◦speedometer
◦fuel gauge
Industry
◦Automation
◦Process control
◦Boiler control
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19. Unit-I : Basics of Transducers
Transducer: Definition, Classification, Selection criteria.
Errors, loading effects, Transducer Specifications,
calibration, Generalized Instrumentation diagram.
Static characteristics: Accuracy, Precision, Sensitivity,
Threshold, Resolution, Repeatability and Hysteresis.
Errors: Gross error, Systematic error, Random error,
Limiting error.
Statistical Parameters: Arithmetic mean Average
deviation Standard deviation. Probable error, Histogram,
Normal & Gaussian curve of errors.
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20. Unit-II : Measurement of Displacement, Liquid Level
Measurement of Displacement:
Resistive, Capacitive, Inductive
Measurement of Liquid Level: Resistive, Capacitive,
Inductive, Ultrasonic, Gamma Rays.
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21. Unit-III : Measurement of Temperature
Measurement of Temperature: Resistance temperature
detector (RTD): Principle, types, Configurations,
construction and working of RTD, Material for RTD,
advantages, disadvantages and applications of RTD.
Thermistors: Principle, types (NTC and PTC), characteristics,
Construction and working of Thermistor, Materials,
specifications of Thermistor, applications.
Thermocouples: Principle, thermoelectric effect, See beck
effect, Peltier effect, laws of thermocouple, cold junction
Compensation method, thermopile, thermocouple emf
measurement method.
Pyrometers: Principle, Construction and working of Radiation and optical
pyrometers and its Applications, LM 335.
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22. Unit-IV : Measurement of Pressure, Flow, Humidity.
◦Measurement of Pressure: Primary pressure sensors - elastic
elements like bourdon tube, diaphragm, and bellows.
Electrical/Secondary Pressure
◦Transducers: Capacitive, piezo-electric and its material,
variable reluctance, LVDT.
◦Differential pressure measurement: Capacitive. Low Pressure
(Vacuum): Pirani gauge, thermocouple gauge, hot cathode
ionization gauge.
◦Flow Measurement: ultrasonic, electromagnetic & hotwire
Anemometer.
◦Flow Measurement: ultrasonic, electromagnetic & hotwire
Anemometer.
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23. Unit-V : Measurement of Velocity, Strain & Miscellaneous Sensors
Velocity Measurement: Using photo detectors (both
linear & angular velocity), Stroboscope.
Strain Measurement: Introduction, types of strain gauge,
gauge factor calculation, materials for strain gauge,
resistance strain gauge bridges, temperature compensation
and applications of strain gauges.
Miscellaneous Sensors: Noise (sound) Sensors
Characteristics of sound, levels of sound pressure, sound
power and sound intensity.
Smart sensors: Objective, block diagram, advantages and
disadvantages.
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24. Unit-VI : Data acquisition and applications of
Electronic Instruments
◦Analog & Digital data acquisition system.:
Generalized block diagram of data acquisition
system(DAS), objective of DAS, signal conditioning of
inputs, single channel DAS, Multichannel DAS,
computer based DAS
◦Digital transducer: optical encoders, shaft encoders
◦pH and blood pressure measurement.
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25. Sr.No.Title Author Publications
1 A course in Electrical and Electronic Measurement
and Instrumentation
Sawhney A.K. Dhanpat Rai & Sons.,
Delhi
2 Electronics Instrumentation H. S. Kalsi Tata McGraw Hill, 2nd
Edition
3 Instrumentation Measurement & analysis B C Nakra Tata Mc-Graw Hill.
4 Instrumentation, devices and systems Rangan Mani, Sharma Tata Mc-Graw Hill.
5 Electronics Instrumentation U.A. Bakshi & A. V.
Bakshi
Technical
Publication
6 Modern Electronic Instrumentation and
Measurement Tech
Helfrick, Cooper Prentice hall
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