EX-504-A Industrial Electronics - Jun 2025 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
   aDiscuss the operation of single-phase half-wave rectifier with RE load. Also derive its average output voltage equations.
   How to answer

   • Circuit diagram of single-phase half-wave rectifier with RE load and operation in conduction and blocking modes
   • Waveforms of input voltage, output voltage and load current with effect of back EMF
   • Derivation steps for average output voltage considering conduction angle
   • Final expression for average output voltage and conclusion
2. 7 Marks
   bDiscuss the advantages and disadvantages of full-wave rectifiers in power supply applications.
   How to answer

   • Principle of full-wave rectifiers in power supplies
   • Advantages such as lower ripple, higher efficiency and better transformer utilization
   • Disadvantages such as extra diodes / centre-tap, cost and complexity
   • Overall suitability for power supply applications
3. 7 Marks
   aDraw the VI characteristics of SCR and mark the holding current and latching current in the characteristic.
   How to answer

   • Structure of SCR VI characteristics with forward blocking, forward conduction and reverse blocking regions
   • Marking of breakover voltage, holding current and latching current on curve
   • Difference between latching and holding current
   • Neat labelled diagram
4. 7 Marks
   bDiscuss the various turn-on and turn-off methods of SCR circuit.
   How to answer

   • Different turn-on methods: gate triggering, forward voltage, dv/dt, temperature and light triggering
   • Turn-off / commutation methods: natural and forced commutation
   • Brief working of each method with circuit condition
   • Comparison of applicability
5. 7 Marks
   aWrite the applications of MOSFET, IGBT and SCR.
   How to answer

   • Typical applications of MOSFET in switching and power supplies
   • Typical applications of IGBT in drives, inverters and high power
   • Typical applications of SCR in rectifiers, control and HVDC
   • Reason for selection based on rating and speed
6. 7 Marks
   bExplain the principles of operation and features of Insulated Gate Bipolar Transistors (IGBTs).
   How to answer

   • Construction and symbol of IGBT combining MOSFET gate and BJT output
   • Principle of operation with gate control and conductivity modulation
   • Key features: high input impedance, low on-state loss, voltage rating
   • Transfer and output characteristics
7. 7 Marks
   aDiscuss the applications of Operational Amplifier (OP-AMPs) in electronic circuits.
   How to answer

   • Ideal OP-AMP basics relevant to applications
   • Linear applications: amplifier, adder, subtractor, integrator, differentiator
   • Non-linear applications: comparator, Schmitt trigger, rectifier
   • Role in electronic circuits
8. 7 Marks
   bDescribe how an OP-AMP can be used as a function generator.
   How to answer

   • Basic function generator concept using OP-AMP
   • Circuit with integrator and Schmitt trigger in loop for square and triangular waves
   • Working and frequency of oscillation expression
   • Waveforms of generated signals
9. 14 Marks
   Explain the functions and applications of Programmable Logic Controllers (PLCs) in industrial automation.
   How to answer

   • Definition and architecture of PLC in industrial automation
   • Main functions: input scanning, logic solving, output control, timers and counters
   • Applications in manufacturing, process and sequential control
   • Benefits for automation
10. 7 Marks
    aDescribe the programming language and basic programming examples used in PLCs.
    How to answer

    • Standard PLC programming languages: ladder logic, function block, structured text
    • Basic instructions: contacts, coils, timers, counters
    • Simple programming examples with rungs
    • Scan execution concept
11. 7 Marks
    bCompare PLCs with conventional relay controllers and discuss the advantages and disadvantages of using PLCs in process control applications.
    How to answer

    • Construction and working of conventional relay controllers vs PLC
    • Comparison on flexibility, size, reliability, maintenance and cost
    • Advantages of PLCs in process control
    • Disadvantages / limitations of PLCs
12. 14 Marks
    Explain the concept of ladder logic language used in PLC programming. Provide examples of ladder logic diagrams and explain how they represent control logic in PLC programs.
    How to answer

    • Concept of ladder logic as relay-equivalent graphical language with rails and rungs
    • Basic symbols: NO/NC contacts, coils, timers, counters
    • Example ladder diagrams for AND, OR, latching and motor control
    • How rungs represent control logic execution in PLC scan
13. 14 Marks
    Write short notes (Any Two):

    1. a)Switch Mode Power Supply
    2. b)Power MOSFET
    3. c)Wien Bridge Oscillator
    How to answer

    • Principle, block diagram and working of Switch Mode Power Supply
    • Structure, characteristics and applications of Power MOSFET
    • Circuit, working and frequency expression of Wien Bridge Oscillator
    • Any two topics with diagrams and uses in full detail