Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech IV UTILIZATION OF ELECTRIC POWER Previous Question Paper (September - 2022 - R16)
Answer any Five Questions. All Questions Carry Equal Marks.
Main
Explain various types of Industrial loads.
Answer
Industrial loads are categorized based on their torque-speed characteristics and operational requirements, which dictate the selection of the electric motor drive. The primary types are:
- Constant Torque Loads: These loads require constant torque regardless of the operating speed. Power varies linearly with speed. Examples include conveyors, positive displacement pumps, and reciprocating compressors.
- Variable Torque Loads: In these loads, torque is proportional to the square of the speed, and power is proportional to the cube of the speed. Common examples include centrifugal pumps and fans.
- Constant Power Loads: These loads require constant power output, meaning torque is inversely proportional to speed. Typical applications include metal cutting tools, tension reels, and winding machines.
- High Starting Torque Loads: These loads require a significantly higher torque at the moment of starting compared to the running torque to overcome static friction or inertia. Examples include crushers, plunger pumps, and loaded conveyors.
Compare a group drive and an individual drive.
Answer
| Feature | Group Drive | Individual Drive |
|---|---|---|
| Motor usage | One motor drives multiple machines via line shafts and belts. | One dedicated motor drives a single machine. |
| Efficiency | Lower due to high friction losses in shafts and belts. | Higher as transmission losses are eliminated. |
| Flexibility | Poor; machines must be located near the line shaft. | Excellent; machines can be placed anywhere. |
| Reliability | Low; failure of the main motor stops all machines. | High; failure affects only one machine. |
| Maintenance | Complex due to mechanical transmission components. | Simple and localized. |
| Cost | Lower initial cost for multiple units. | Higher initial cost. |
What are the various types of motors for the following services? Explain:
i) Rolling mills ii) Textile machinery iii) Household applications
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Explain various speed control methods of electric drives.
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How is resistance heating carried out? What are the characteristic features of heating elements?
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Describe the core type induction furnace with a neat sketch and state its applications.
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Describe the following welding process:
a) Resistance welding b) Seam welding c) Butt welding and d) Projection welding.
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Discuss the relevant features of flood lighting.
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Explain the following: (i) Brightness (ii) Glare (iii) Candela (iv) M.S.C.P
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Explain the working of a Mercury Vapour lamp with a neat sketch. State the need of a choke in a discharge lamp.
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How many types of train services railways have to cater for and what are their distinguishing features?
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A train runs at an average speed of 50 Kmph between stations situated 6 km apart. Train accelerates at 3 Kmphps and retards at 4 kmphps. Find its maximum speed assuming simplified trapezoidal speed time curve. Draw the speed time curve for the run and also, calculate the distance travelled by it before the brakes are applied.
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What is the coefficient of adhesion? How the value of coefficient of adhesion affects the slipping and skidding of the driving wheels of a traction unit?
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Derive an expression for tractive effort developed by the driving wheel of a train?
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