Week 1
-
Upload
tausique-sheikh -
Category
Engineering
-
view
162 -
download
0
Transcript of Week 1
![Page 1: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/1.jpg)
INSTRUMENTATION & MEASUREMENTS(EE-302)
WEEK 1
UIT SPRING 20161
![Page 2: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/2.jpg)
The Course…..
Instrumentation and measurements constitute the fundamental skills of an engineer.
In the field you can’t work without the proper knowledge of instrumentation and consequently measurements.
Instrumentation has a extremely wide scope involving analog as well as digital sides.
In this course we are going to learn some very exciting, practical and application oriented measurements techniques as well as get the knowledge of a number of basic as well as advanced instruments and processes.
UIT SPRING 2016 2
![Page 3: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/3.jpg)
Lets formally define ‘measurements’
The measurement of a given parameter or quantity is the act or result of a quantitative comparison between a pre-defined standard and an unknown quantity to be measured!
UIT SPRING 20163
![Page 4: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/4.jpg)
Meaningful result would require…
The comparison standard is accurately defined.
The procedure and the instrument used for obtaining the comparison must be provable!
A measuring instrument is defined as a device for determining the value or magnitude of a quantity or variable.
An electronic measuring instrument is the one in which electronic/electrical principles for its measurement function are used.
The physical, chemical, electrical quantity, property, process, variable or a condition to be measured is referred as measurand.
UIT SPRING 2016 4
![Page 5: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/5.jpg)
Advantages of Electronic measurement
Involvement of Transducers that could measure almost any physical quantity.
Ease of digital conversion.
Amplification, Filtering, Multiplexing and Sampling possible.
Long distance transmission of signals easier.
Multiple measurements could be conducted simultaneously.
Extremely short time duration as well as weak signals could be measured.
Higher sensitivity, low power consumption, high reliability.
UIT SPRING 20165
![Page 6: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/6.jpg)
Functional Elements of an instrument
UIT SPRING 20166
![Page 7: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/7.jpg)
Primary Sensing Element is a transducer.
Transducer is a device that could convert one form of energy into the other, for our case of electronic transducer, it can convert any physical quantity into an analog electrical signal.
A variable conversion element makes the output of the transducer suitable for measurement and recording (think of a A/D converter)
A variable manipulation element is a signal conditioning element or a data conditioning element.
Data Transmission Elements are used when the system’s elements are physically separated.
UIT SPRING 2016 7
Functional Elements of an instrument
![Page 8: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/8.jpg)
Data Presentation Element is used to present the data in the format so that it could be used either to control, observe or manipulate the system.
Data and its handling could be explained by a simple example of the ammeter block as follows:
UIT SPRING 2016 8
Functional Elements of an instrument
![Page 9: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/9.jpg)
A simple analog Ammeter
UIT SPRING 20169
![Page 10: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/10.jpg)
Performance Characteristics
Two basic categories:
Static Characteristics
Dynamic Characteristics
UIT SPRING 201610
![Page 11: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/11.jpg)
Static & Dynamic Characteristics
The set of criteria defined for instruments which are used to measure the quantities which are slowly varying with time or mostly constant i.e do not vary with time is called static characteristics.
When the quantity under measurement changes rapidly with time, it is necessary to study the dynamic relations between the input and the output generally expressed with differential equations, thus the set of criteria defined based on such differential equations is called dynamic characteristics.
UIT SPRING 201611
![Page 12: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/12.jpg)
Calibration
Calibration is the process of making an adjustment or marking a scale so that the readings of an instrument agree with the accepted and the certified standard.
UIT SPRING 201612
![Page 13: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/13.jpg)
Static Characteristics
Accuracy
Precision
Resolution
Error
Sensitivity
Threshold
Reproducibility
Zero Drift
Stability
Linearity
UIT SPRING 201613
![Page 14: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/14.jpg)
Accuracy is the degree of closeness with which the instrument reading approaches the true value of the quantity to be measured.
Precision is the measure of consistency or repeatability of measurements.
High degree of precision does not necessarily guarantees the accuracy. Calibration makes accurate measurements possible.
Precision is composed of Conformity and Number of Significant figures.
UIT SPRING 201614
Static Characteristics
![Page 15: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/15.jpg)
UIT SPRING 2016 15
![Page 16: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/16.jpg)
UIT SPRING 2016 16
![Page 17: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/17.jpg)
Precision mathematically…
UIT SPRING 2016 17
![Page 18: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/18.jpg)
UIT SPRING 2016 18
![Page 19: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/19.jpg)
Explaining Conformity and Number of Significant Figures
A resistor having a true value of 2358692Ω might be represented by the instrument as 2.4 MΩ. This has been estimated due to the non availability of the proper scale. This value is estimated by the reader from the available scale. The error created due to the limitation of the scale reading is the precision error.
An accurate instrument should be precise but a precise instrument may not be accurate.
Likewise a resistance 110Ω specified by an instrument may be closer to 109Ω or 111Ω, thus there are three significant figures. But when it is specified as 110.0Ω the number of significant figures changes from 3 to 4.
The greater the number of significant figures, the greater the precision of the measurement.
UIT SPRING 2016 19
![Page 20: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/20.jpg)
Error & Sensitivity
The algebraic difference between the indicated value and the true value of the quantity to be measured is called an error.
UIT SPRING 2016 20
![Page 21: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/21.jpg)
Absolute Error
Absolute error is a measure of how far 'off'a measurement is from a true value or anindication of the uncertainty in ameasurement
Absolute Error = Actual Value - Measured Value
![Page 22: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/22.jpg)
Relative Error
Relative error expresses how largethe absolute error is compared withthe total size of the object
Relative Error = Absolute Error / Actual Value
![Page 23: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/23.jpg)
Sensitivity
The sensitivity denotes the smallest change in themeasured variable to which the instrument responds.
UIT SPRING 2016 23
![Page 24: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/24.jpg)
UIT SPRING 2016 24
Sensitivity
If the calibration of the curve is not linear, the sensitivityVaries with the input.
![Page 25: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/25.jpg)
Deflection factor is expressed as the reciprocal of sensitivity.
The sensitivity of the instrument should be as high as possible, and to achieve this the range of an instrument should not greatly exceed the value to be measured.
UIT SPRING 2016 25
Sensitivity
![Page 26: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/26.jpg)
Some basic definitions
Resolution: It is the smallest increment of quantity being measured which can be detected with certainty, thus the resolution means the smallest measureable input change.
Threshold: The smallest measurable input.
Linearity: Indicates the straight line nature of the calibration curve.
UIT SPRING 2016 26
![Page 27: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/27.jpg)
Zero Drift: The deviation in the instrument’s output with time, from its zero value, when the variable to be measured is constant.
Reproducibility: The degree of closeness with which a given value may be repeatedly measured.
UIT SPRING 2016 27
Some basic definitions
![Page 28: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/28.jpg)
Stability: The ability of the instrument to retain its performance throughout its specified operating / storage life.
Tolerance: The maximum allowable error in the measurement . This is related to accuracy.
Range of Span: Minimum and Maximum values of a quantity for which an instrument is designed.
Bias: The constant error which exists over the entire range of measurement of an instrument.
UIT SPRING 2016 28
Some basic definitions
![Page 29: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/29.jpg)
Hysteresis: Change in theresponse when the input ischanged from negative topositive or positive tonegative values is calledhysteresis. (The magneticdomains example of anelectromagnet) .
Dead Space: The range ofinput after which the outputresponds to input and getschanged.
UIT SPRING 201629
Some basic definitions
![Page 30: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/30.jpg)
Dynamic Characteristics
When the instrument is subjected to rapidly varying input, the output also varies instant to instant.
The behaviour of the system under such conditions is called the dynamic response of the system.
The dynamic response of the system is checked after applying certain basic known and pre-determined variations of the input to the sensing element and such a response is expressed mathematically by differential equations.
UIT SPRING 2016 30
![Page 31: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/31.jpg)
Dynamic Inputs
UIT SPRING 2016 31
![Page 32: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/32.jpg)
Dynamic Characteristics of instruments
Speed of response
Fidelity
Lag
Dynamic Error
UIT SPRING 2016 32
![Page 33: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/33.jpg)
Dynamic Characteristics
Speed of Response: Rapidity with which the system responds to the changes in the being measured quantity.
Fidelity: How faithfully the system reproduces the changes in the input.
Lag: Retardation or delay in the response of a system.
Dynamic Error: Assuming zero static error the difference in the true and measured values of a system’s variable.
UIT SPRING 2016 33
![Page 34: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/34.jpg)
Dynamic Error Explained…
UIT SPRING 2016 34
![Page 35: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/35.jpg)
Instrument Classification
UIT SPRING 2016 35
![Page 36: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/36.jpg)
Active/Passive Instruments
UIT SPRING 2016 36
![Page 37: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/37.jpg)
Null/Deflection Type Instruments
UIT SPRING 2016 37
![Page 38: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/38.jpg)
Monitoring/Control Instruments
UIT SPRING 2016 38
![Page 39: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/39.jpg)
Analog/Digital Instruments
UIT SPRING 2016 39
![Page 40: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/40.jpg)
Absolute and Secondary Instruments
Absolute Instruments: That give the measured value in terms of the physical constants of the instrument.
Secondary Instruments: That give the measured value directly.
UIT SPRING 2016 40
![Page 41: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/41.jpg)
Methods of Measurement
Direct Method: The quantity to be measured is used to produce certain effect that directly gives the indication on the meter. Further classified into Deflection Methods and Comparison methods.
Indirect Method: The quantity to be measured is not directly measured but other parameters related to the quantity are measured.
UIT SPRING 2016 41
![Page 42: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/42.jpg)
Calibration Methodologies
Direct Comparison
Indirect Comparison
UIT SPRING 2016 42
![Page 43: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/43.jpg)
UIT SPRING 2016 43
Calibration Methodologies
![Page 44: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/44.jpg)
UIT SPRING 2016 44
Calibration Methodologies
![Page 45: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/45.jpg)
Units
The SI International System of Units (abbreviated SI from French: Le SystèmeInternational d'Unités) is divided into :
Fundamental Unites
Supplementary Units
Derived Units
The units which are independently chosen and not dependent upon any other unit are called base or fundamental units.
In the these fundamental units are Meter (m), Kilogram (kg), Second (s), Ampere (A), Kelvin (K), Mole (mol), Candela (cd)
UIT SPRING 2016 45
![Page 46: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/46.jpg)
The two Supplementary Units added into the SI system of units are:
Radian for the plane angles
Steradian for the Solid Angle
UIT SPRING 2016 46
Units
![Page 47: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/47.jpg)
Derived Units
Units other than fundamental and supplementary are derived from the fundamental and supplementary units and are primarily classified into:
Mechanical Units like mass, velocity, acceleration, force, weight, torque, work, energy, power etc.
Electric and Magnetic Units such as power, energy, ohms, farads, henries, magnetic flux in webers, tesla etc.
Thermal Units such as latent heat specific heat capacity, sensible heat, calorific value etc.
UIT SPRING 2016 47
![Page 48: Week 1](https://reader031.fdocuments.net/reader031/viewer/2022030316/5872c9be1a28ab0c718b6f99/html5/thumbnails/48.jpg)
Problems
A set of solved problems related to Units shall be provided soon.
UIT SPRING 2016 48