Mahatma Gandhi University (MGU) 2007 B.Tech Electrical and Electronics Engineering ELECTRICAL SYSTEM DESIGN -- (E) - Question Paper

G 1799 (Pages : 2)
Reg. No…………………..
Name……………………..
B.TECH. DEGREE EXAMINATION, JULY/AUGUST 2007
Eighth Semester
Branch : Electrical and Electronics Engineering
ELECTRICAL SYSTEM DESIGN -- (E)
(New Scheme – 2002 admission onwards)
(Regular/Supplimentary)
Time : 3 Hours Maximum : 100 Marks


ans all ques.
presume any missing data.
Part A
every ques. carries four marks.
1. Compare ranging from core kind and shell kind transformers.
2. Distinguish ranging from distribution and power transformers.
3. explain the design details of ventilating ducts of 3-phase induction motor.
4. Determine the diameter and length of a 3000 kVA, 6.6 kV, 50 Hz, 187.5 r.p.m. 3-phase star connected alternator. presume avg. gap density = 0.58 Wb/m2, winding factor = 0.955, ampere conductor / metre = 35000.
5. What is Carter’s coefficient?
6. What do you understand by earthing? Why is it necessary to earth electrical installation?
7. Write a short note on plate earthing.
8. Draw the schematic layout of a substation and low voltage switchboard.
9. What is meant by specific magnetic and electric loading of synchronous machine?
10. provide and prove the relation ranging from freq. number of poles and synchronous speed of a 3-phase induction motor. [10 x four = 40 Marks]
Part B
11. (a) explain the steps for the design of shunt field winding of d.c. machine. [12 marks]
(b) discuss the designing details of height of the pole of a d.c. machine. [8 marks]
Or
12. (a) discuss the terms : (i) window space factor; (ii) stacking factor. [6 marks]
(b) Derive the output formula of a 3-phase core kind transformer. [14 marks]
13. Determine the dimensions of the core and yoke for a 100kVA, 50Hz, 1-phase core kind transformer. A square core is used with distance ranging from the adjacent limbs equal to 1.6 times the width of the laminations. presume voltage per turn of 14 volts, maximum flux density 1.1 Wb/m2, window space factor = 0.32 and the current density three A/mm2. Take stacking factor = 0.9. Flux density in the yoke to be 80% of flux density in core. presume missing data. [20 marks]
Or
14. compute the diameter, core length, number of conductors of the stator, size of the conductor and no. of stator slots of a 30 MVA, 11kV, 3000 r.p.m., 50Hz star connected turboalternator. presume Bav = 0.55 Wb/m2, ac = 55000 A/m, Kw = 0.955, periferal velocity = 160 m/s. Kw – window space factor. Ac – specific electric loading. presume the missing data. [20 marks]

15. Draw the electrical wiring layout and estimate the volume of materials needed with cost of a Cinema Hall with necessary accessories and facilities. [20 marks]
Or
16. Estimate the volume of material needed for erection of a 200kVA polemounting substation [20 marks]
(3 x 20= 60 Marks)

Earning:   Approval pending.