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ELECTRONIC INSTRUMENTATION Reference Books Measurement System : Ernest O Doebelin Measurement System : Ernest O Doebelin Electronic Instrumentation : H.S Kalsi
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  • ELECTRONIC INSTRUMENTATION

    Reference Books Measurement System : Ernest O Doebelin Electronic Instrumentation : H.S Kalsi

    Reference Books Measurement System : Ernest O Doebelin Electronic Instrumentation : H.S Kalsi

  • Electronic Instrumentation Instrumentation is a branch of engineering

    that deals with the measurement and controlof different parameters.

    Instrumentation is defined as "the artand science of measurement and control".

    Measuring is used to monitor a process oroperation

    Instrumentation is a branch of engineeringthat deals with the measurement and controlof different parameters.

    Instrumentation is defined as "the artand science of measurement and control".

    Measuring is used to monitor a process oroperation

  • UNIT 1

    Objectives ofEngineering Measurement

    Objectives ofEngineering Measurement

  • Objectives At the end of this Unit

    Basic measuring systemPerformance characteristics of

    instrumentsErrors in measurementUnits-Dimensions Standards.Instrument calibration.

    At the end of this Unit

    Basic measuring systemPerformance characteristics of

    instrumentsErrors in measurementUnits-Dimensions Standards.Instrument calibration.

  • Objectives Of Engineering Measurements

    1. Measurements of system parameterinformation.

    2. Automatic control of a system.

    3. Simulation.

    4. Experimental design.

    5. To perform various manipulation.

    6. Testing of materials and quality control.

    7. Verification of scientific theories.

    1. Measurements of system parameterinformation.

    2. Automatic control of a system.

    3. Simulation.

    4. Experimental design.

    5. To perform various manipulation.

    6. Testing of materials and quality control.

    7. Verification of scientific theories.

  • Basic Measuring System A measurement assigns a specific value to a

    physical variable. The physical variable nowbecomes the measured variable.

    A measurement system is a tool used to measurethe physical variable.

    Methods of measurement can be classified in totwo

    Direct methods Un known quantity is directly compared against a

    standard Result is expressed as a numerical number

    In direct methods In engineering application measurement systems

    uses this methods

    A measurement assigns a specific value to aphysical variable. The physical variable nowbecomes the measured variable.

    A measurement system is a tool used to measurethe physical variable.

    Methods of measurement can be classified in totwo

    Direct methods Un known quantity is directly compared against a

    standard Result is expressed as a numerical number

    In direct methods In engineering application measurement systems

    uses this methods

  • Simple measuring systemSignal conditioningelement

    Data transelement

    Data processingelement

    Primary sensingelement

    Transducer

    Data display

    Transducer

    Data recording

  • Basic Measuring System Four Parts of Measurement System

    Sensor-Transducer Stage Signal Conditioning Stage Output Stage

  • Sensor The sensor is a physical element that uses some

    natural phenomenon to sense the variable beingmeasured.

    The transducer changes this sensed informationinto a detectable signal form (electrical,mechanical, optical, etc.)

    A Transducer is a device which converts one formof energy into some other form of energy

    It is also known as 'Pickup Element'.

    The sensor is a physical element that uses somenatural phenomenon to sense the variable beingmeasured.

    The transducer changes this sensed informationinto a detectable signal form (electrical,mechanical, optical, etc.)

    A Transducer is a device which converts one formof energy into some other form of energy

    It is also known as 'Pickup Element'.

  • Sensor Mainly Transducers can be classified into two types on

    the basis of power supply required Active Transducers Passive Transducers. Active transducers are those which does not requires

    external power supply for their operation. For example: Photo Voltage Cell, Piezo Electric Crystal,

    Generator etc. Passive Transducers: Passive Transducers are those

    transducers which requires external power supply fortheir operation.

    For Example: Resistive, Inductive and CapacitiveTransducers.

    Mainly Transducers can be classified into two types onthe basis of power supply required

    Active Transducers Passive Transducers. Active transducers are those which does not requires

    external power supply for their operation. For example: Photo Voltage Cell, Piezo Electric Crystal,

    Generator etc. Passive Transducers: Passive Transducers are those

    transducers which requires external power supply fortheir operation.

    For Example: Resistive, Inductive and CapacitiveTransducers.

  • Signal Conditioner

    Its role comes into play when the output oftransducer or primary sensing element is verylow. It is used to amplify or modify the incomingsignal from transducer according to outputrequirement.

    When noise is present in signal, filters need to beused to eliminate it.

    If the processor operates only on digital signal,A/D and D/A converters must be used at theinput and output of the processor

    In other words Signal Conditioning is done toimprove the quality of output of measurementsystem.

    Its role comes into play when the output oftransducer or primary sensing element is verylow. It is used to amplify or modify the incomingsignal from transducer according to outputrequirement.

    When noise is present in signal, filters need to beused to eliminate it.

    If the processor operates only on digital signal,A/D and D/A converters must be used at theinput and output of the processor

    In other words Signal Conditioning is done toimprove the quality of output of measurementsystem.

  • Signal Conditioner This optional intermediate stage can be used to

    increase

    The magnitude of the signal throughamplification,

    Remove portions of the signal through somefiltering technique,

    Provide mechanical or optical linkage betweenthe transducer and the output range.

    This optional intermediate stage can be used toincrease

    The magnitude of the signal throughamplification,

    Remove portions of the signal through somefiltering technique,

    Provide mechanical or optical linkage betweenthe transducer and the output range.

  • O/P stage The output unit of a measurement system is

    consists of a display and storage unit

    It is used to display or analyze the final outputof the measurement system.

    The examples of Output unit can be anyoutput device like CRO (Cathode RayOscilloscope) or XY recorder.

    The output unit of a measurement system isconsists of a display and storage unit

    It is used to display or analyze the final outputof the measurement system.

    The examples of Output unit can be anyoutput device like CRO (Cathode RayOscilloscope) or XY recorder.

  • ComparisonDigital Signal Analog Signal Data Storage can be

    easily done Processing of digital

    information is very easy Will not interfere with

    other signals, so lessaffected with Noise. Datatransmission quality isgood

    Repeaters are requiredfor long distancecommunication

    Difficult to store thesignal/information

    Processing of signal isdifficult

    Will interfere with othersignals, so affected withnoise. Transmissionquality is comparativelypoor

    Repeaters are notrequired

    Data Storage can beeasily done

    Processing of digitalinformation is very easy

    Will not interfere withother signals, so lessaffected with Noise. Datatransmission quality isgood

    Repeaters are requiredfor long distancecommunication

    Difficult to store thesignal/information

    Processing of signal isdifficult

    Will interfere with othersignals, so affected withnoise. Transmissionquality is comparativelypoor

    Repeaters are notrequired

  • Performance characteristics ofinstruments

    JOBY JOHN 15

    Performance characteristics ofinstruments

  • Performance characteristics of instruments

    A knowledge of the performancecharacteristics of an instrument is essential forselecting the most suitable instrument forspecific measuring jobs.

    Performance characteristics of an instrumentare mainly divided into two.

    Static characteristics Dynamic characteristics

    A knowledge of the performancecharacteristics of an instrument is essential forselecting the most suitable instrument forspecific measuring jobs.

    Performance characteristics of an instrumentare mainly divided into two.

    Static characteristics Dynamic characteristics

  • STATIC CHARACTERISTICS

    The set of criteria defined for the instrumentwhich are used to measure the quantities thatare varying slowly with time or constant is calledstatic characteristics.

    OR The static characteristics of an instrument are

    considered for instruments which are usedto measure an unvarying process condition.

    Some criteria will be set to for the measurementof quantities that are either constant or varyslowly is called static characteristics

    The set of criteria defined for the instrumentwhich are used to measure the quantities thatare varying slowly with time or constant is calledstatic characteristics.

    OR The static characteristics of an instrument are

    considered for instruments which are usedto measure an unvarying process condition.

    Some criteria will be set to for the measurementof qua