ME-402 Instrumentation and Control - Jun 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aExplain various elements of a measurement system.
   How to answer

   • Define measurement system and its need
   • List elements: primary sensing, transduction, signal conditioning, display/record
   • Explain function of each stage with example
   • Block diagram of generalized measurement system
2. 7 Marks
   bExplain Static Performance Characteristics with diagrams?
   How to answer

   • Define static characteristics
   • Explain accuracy, precision, sensitivity, linearity, hysteresis, repeatability
   • Explain threshold, resolution, drift, stability
   • Draw input-output diagrams for linearity, hysteresis, etc.
3. 7 Marks
   aThe accuracy of pressure gauge of range $1000\text{ kN/sq.m}$ is stated to be $\pm 1\%$ of full scale deflection. What would be the possible readings if the pressure is $100\text{ kN/sq.m}$. How these results would get modified if the error is specified as $\pm 1\%$ of true value.
   How to answer

   • Calculate absolute error as 1% of full scale = 10 kN/sq.m
   • Find possible readings at 100 kN/sq.m as 90 to 110 kN/sq.m
   • Calculate error as 1% of true value = 1 kN/sq.m
   • Compare FSD vs true-value specification effect
4. 7 Marks
   bExplain briefly about:

   1. i)Fidelity
   2. ii)Speed of response
   How to answer

   • Define fidelity in dynamic measurement
   • Define speed of response / response time
   • Explain with example of instrument following input
   • Relate to dynamic performance characteristics
5. 7 Marks
   aExplain briefly about harmonic signal and non harmonic signal system?
   How to answer

   • Define harmonic signal with sinusoidal form
   • Define non-harmonic / complex signal
   • Explain harmonic vs non-harmonic systems
   • Give examples of each
6. 7 Marks
   bDescribe briefly about first and second order in measurement system with suitable examples.
   How to answer

   • Define zero, first and second order systems
   • Give differential equation forms and examples
   • Explain step response characteristics
   • Compare with thermometer, accelerometer examples
7. 7 Marks
   aExplain the working of glass thermometer with diagram. What are its advantages and limitations?
   How to answer

   • Draw glass thermometer construction with bulb, capillary, scale
   • Explain thermal expansion of liquid principle
   • List advantages: simple, cheap, direct reading
   • List limitations: fragile, slow, non-continuous
8. 7 Marks
   bDiscuss about the following:

   1. i)Thermistor
   2. ii)Bi-metallic strip.
   How to answer

   • Explain thermistor principle and resistance-temperature relation
   • Explain bi-metallic strip differential expansion bending
   • Give construction diagrams for both
   • List applications of each
9. 7 Marks
   aExplain with diagrams, Why are two different metals required in a thermocouple?
   How to answer

   • Explain Seebeck effect with two dissimilar metals
   • Draw thermocouple circuit with hot and cold junctions
   • Explain why same metal gives no net emf
   • Explain laws of thermocouple
10. 7 Marks
    bWhat is bellows gauge? Explain the working of Bellow gauge with suitable diagram and give its applications.
    How to answer

    • Define bellows gauge and its construction
    • Explain pressure-induced expansion and displacement measurement
    • Draw diagram with bellows, spring, pointer
    • List applications for low pressure measurement
11. 7 Marks
    aDescribe the principle of operation of a Piezo-electric transducer. Discuss about the different applications of it.
    How to answer

    • Define piezoelectric effect direct and inverse
    • Explain crystal deformation producing charge
    • Draw transducer construction with electrodes
    • List applications: accelerometers, pressure pickups
12. 7 Marks
    bA $150\text{ ohm}$ Strain Gauge is bonded to a steel bar which is subjected to a tensile load. Cross sectional area of the bar is $0.5 \times 10^{-4}\text{ sq.m.}$ and Youngs modulus for the bar material is $200\text{ GN/sq.m.}$ If a load of $60\text{ kN}$ produces a change of $1.5\text{ Ohm}$ in the gauge resistance, determine the gauge factor of the gauge.
    How to answer

    • Calculate stress = load / area
    • Calculate strain = stress / Young's modulus
    • Use gauge factor $G_f = (\Delta R/R)/\epsilon$
    • Substitute $R=150\,\Omega$, $\Delta R=1.5\,\Omega$ to get $G_f$
13. 7 Marks
    aExplain about closed loop system. Give the advantages of a closed loop system.
    How to answer

    • Define closed loop / feedback control system
    • Draw block diagram with comparator, controller, plant, feedback
    • Explain error-actuated control action
    • List advantages: accuracy, disturbance rejection, stability
14. 7 Marks
    bA constant water level is to be maintained in a boiler. Suggest a suitable automatic level control system with a block diagram and explain its working.
    How to answer

    • Identify level sensor, controller, feed valve as elements
    • Draw closed-loop block diagram for boiler drum
    • Explain error correction when level deviates
    • Mention safety and steady steam supply
15. 14 Marks
    Write a short note on any two of the following:

    1. a)Barometer
    2. b)Potentiometer
    3. c)Venturimeter
    4. d)Impulse function
    How to answer

    • Select any two instruments/functions
    • Explain construction and working principle
    • Give diagram and formula where applicable
    • List applications