Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January EE 7th Sem 71945 Energy Efficient Machines Previous Question Paper
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech. (EE) (2012 Onwards E-III) (Sem.?7)
ENERGY EFFICIENT MACHINES
Subject Code : BTEE-805D
M.Code : 71945
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Write briefly :
1.
How is an energy efficient motor different than a standard motor?
2.
Do energy efficient motors require more maintenance?
3.
Should one rewind my standard-efficiency motor or purchase an energy efficient motor?
4.
What horsepower, speed and voltage ranges are available?
5.
What is the efficiency of an energy efficient motor at different load points?
6.
What is the power factor of an energy efficient motor?
7.
Can a standard motor be rewound as an energy efficient motor?
8.
Is the service factor any different from that of a standard motor?
9.
What is the payback period for selecting an energy efficient versus a standard-efficiency
motor?
10. Aren't energy efficient motors unsuitable for adjustable speed drive applications?
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SECTION-B
11. Write some applications of constant torque and variable torque loads. Write a short note on
a `Multi-Speed Motor'.
12. How do you size the capacitor rating required for an induction motor? Write some
strategies for correcting poor power factor in motors.
13. Comment on `Construction Aspects' how an "Energy Efficient Motor" is different from a
"Standard Motor"? List down some ill-suited applications for `Energy Efficient Motors'.
14. Why `Induction Motors' are so popular over all types of motors? How do you define
percentage unbalance in voltage?
15. Why is it beneficial to operate motors in star mode for under loaded motors? What is the
thumb rule for installing capacitors to motor terminal?
SECTION-C
16. A 4-pole 415 V 3-phase, 50 Hz induction motor runs at 1440 RPM at .88 pf lagging and
delivers.
10.817 kW. The stator loss is 1060 W, and friction & windage losses are 375 W. Calculate
A. Slip, B. Rotor Copper loss, C. Line current and D. Efficiency
17. What are the effects of harmonics on motor operation and performance? Calculate the
annual energy-savings and simple payback from replacing an existing standard motor with
a premium efficiency Motor versus repairing a standard efficiency motor with a sample
example.
18. Discuss direct measurement method and loss segregation method to determine the
efficiency of energy efficient methods.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 26 June 2021