EX-603-A Utilization of Electrical Engineering - May 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 different methods available for aiming of lamp in flood lighting.
   How to answer

   • Define flood lighting and need for aiming.
   • Explain methods: direct aiming, contour aiming, pre-focus aiming / aiming chart.
   • Role of mounting height, beam angle, overlap.
   • Diagram of projector aiming angles.
2. 7 Marks
   bExplain the design considerations for auditorium lighting.
   How to answer

   • Purpose of auditorium lighting: visibility, aesthetics, comfort.
   • Illuminance levels, glare control, colour rendering.
   • Placement of luminaires, dimming, emergency lighting.
   • Energy and maintenance considerations.
3. 7 Marks
   aAn illumination of 25 lux is to be produced on the floor of a room $12\, \text{m} \times 9\, \text{m}$. 18 lamps are required to produce this illumination in the room, if $50\%$ of the emitted light falls on the floor. What is the power of the lamp in Candela?
   How to answer

   • Total lumens required = $E \times A / UF$ with $UF=0.5$.
   • Lumens per lamp = total / 18.
   • Convert lumens to candle power: $I = \Phi / 4\pi$.
   • Compute value in candela.
4. 7 Marks
   bExplain about metal arc welding, submerged arc welding methods with necessary illustrations.
   How to answer

   • Principle of metal arc welding with electrode and arc.
   • Principle of submerged arc welding with flux blanket.
   • Neat labelled illustrations of both setups.
   • Applications and comparison.
5. 6 Marks
   aDiscuss about the criteria to select frequency for heating processes.
   How to answer

   • Penetration depth vs frequency: skin effect.
   • Workpiece size, material resistivity and permeability.
   • Heating rate, efficiency, cost of high-frequency source.
   • Choice for induction vs dielectric heating.
6. 8 Marks
   bA lamp of 500 candle power is placed at the centre of a room having dimensions of $20\, \text{m} \times 10\, \text{m} \times 5\, \text{m}$. Calculate the illumination in each corner of the floor and a point in the middle of a 10 m wall at a height of 2 m from floor.
   How to answer

   • Point source law $E = I \cos\theta / d^2$.
   • Distance to floor corners from centre lamp.
   • Calculate illumination at corners.
   • Calculate illumination at mid-point of 10 m wall at 2 m height.
7. 7 Marks
   aFor a quadrilateral speed-time curve of an electric train, derive expression for the distance between stops and speed at the end of the coasting period.
   How to answer

   • Define quadrilateral speed-time curve: acceleration, free run, coasting, braking.
   • Use areas and slopes to relate $V_m$, $V_2$, times.
   • Derive distance $D$ = area under curve.
   • Derive expression for coasting end speed.
8. 7 Marks
   bAn electric train has an average speed of 42 km/h on a level track between stops 1.4 km apart. It is accelerated at 1.7 km/h/s and is braked at 3.3 km/h/s. Assuming tractive resistance as 50 N/t. allowing 10% for rotational inertia and efficiency to motors 85%. Estimate the specific energy consumption.
   How to answer

   • Find max speed from average speed and $\alpha$, $\beta$, $D$.
   • Calculate tractive effort during acceleration with rotational inertia.
   • Calculate energy output and input using motor efficiency.
   • Compute specific energy consumption in Wh/tonne-km.
9. 7 Marks
   aExplain the reasons for having greater coefficient of adhesion in electric traction when compared to steam traction.
   How to answer

   • Define coefficient of adhesion.
   • Electric locomotive weight distribution and bogie control.
   • Absence of reciprocating unbalance vs steam.
   • Better torque control and anti-slip devices.
10. 7 Marks
    bExplain what do you mean by "Individual drive" and "Group drive"? Discuss their relative merits and demerits.
    How to answer

    • Define Individual drive and Group drive.
    • Schematic arrangement of motors and shafts.
    • Merits: flexibility, reliability, efficiency.
    • Demerits: cost, maintenance, space.
11. 7 Marks
    aExplain about the factors affecting energy consumption in propelling the train.
    How to answer

    • Tractive resistance, gradient, curves.
    • Weight, acceleration, speed-time schedule.
    • Motor efficiency, power supply, driving technique.
    • Strategies to reduce consumption.
12. 7 Marks
    bExplain the effect of varying acceleration and braking retardation in traction.
    How to answer

    • Define acceleration and braking retardation in speed-time curve.
    • Higher acceleration reduces running time but increases energy.
    • Effect on max speed, distance and schedule.
    • Effect of braking rate on coasting and energy regeneration.
13. 7 Marks
    aWhy an energy management control system is required in an HEV?
    How to answer

    • Multiple sources: engine + battery + motor in HEV.
    • Need for optimal power split and SOC control.
    • Fuel economy, emissions and performance.
    • Functions of controller.
14. 7 Marks
    bDo you think an elaborate energy management system similar to that applied to a hybrid vehicle, is required in an electric vehicle? Explain.
    How to answer

    • Difference between HEV (two sources) and pure EV (single source).
    • Simpler management in EV but still need BMS, thermal.
    • Why elaborate hybrid strategy not required.
    • Conclusion with justification.
15. 4 Marks
    aDiscuss the following: Electric drives
    How to answer

    • Define electric drives and classification.
    • Components: motor, controller, transmission.
    • Applications in traction and industry.
16. 5 Marks
    bDiscuss the following: Regenerative braking
    How to answer

    • Principle of regenerative braking.
    • Conversion of kinetic energy to electrical.
    • Conditions and advantages in traction.
    • Limitations.
17. 5 Marks
    cDiscuss the following: Luminous intensity
    How to answer

    • Define luminous intensity in candela.
    • Relation to luminous flux and solid angle.
    • Measurement and significance in lighting.