Anna University Chennai 2003 B.Tech Marine Engineering ELECTRICAL TECHNOLOGY - Question Paper

Time : 3 hours Maximum : 100 marks

ans ALL ques..
PART A — (10x2 = 20 marks)

1.What are the conditions that must be fulfilled for the machine to self excite?
2.Draw a 3 point starter and indicate its important components.
3.A slip ring induction motor runs at 285 rpm on full load when fed from a 50 Hz supply. compute number of poles and slip.
4.What are the advantages of stationary armature and rotating field in synchrous generator?
5.What kind of motor is preferred for traction? Why?
6.Mention the characteristics of motor needed for mining application.
7.Name the kinds of insulators and where they can be used?
8.Draw the layout of transmission and distribution system.
9.Briefly explain the procedure for determining the size of wire for an internal installation.
10.State any 4 important Indian electricity rules.

PART B — (5x16 = 80 marks)

11.(i)Explain the torque-speed characteristics of a 3 phase slip ring induction motor. (8)
(ii)Three loads , and ohm are connected in delta across a 200 V, three phase supply. obtain the phase currents, line currents and power. (8)
12.(a)(i)Describe the construction of armature, field and commutator of a d.c. machine. (8)
(ii)Describe Swinburne test on a shunt motor and provide the steps for calculating the efficiency of a motor from the outcomes of the test. (8)
Or
(b)(i)Bring out the analogy ranging from electric and magnetic circuits. (6)
(ii)Derive the EMF formula of a d.c. generator. (6)
(iii)A motor develops a torque of 150 N-m. A 10% reduction in the field flux causes a 50% increase in armature current. obtain the new value of torque. (4)
13.(a)(i)How will you determine power rating of electric motor for continuous duty and constant load? (8)
(ii)Discuss the requirements of paper machine drive. (8)
Or
(b)(i)Discuss the different classes of duty. (10)
(ii)Determine the 1 hour rating of a 15 h.p. motor having a heating time constant of two hours. The motor attains the temperature of 40?C on continuous run at full load. presume that the losses are proportional to the square of the load and the motor is allowed to cool down to the ambient temperature before being loaded again. (6)
14.(a)(i)Draw the schematic diagram of a modern steam power station and discuss its operation. (8)
(ii)Explain Kelvin’s legal regulations for size of conductor for transmission and its limitations. (8)
Or
(b)(i)How will you determine the economic transmission voltage? (8)
(ii)Compare the quantity of conductor material needed in 2-wire d.c. system with 1 conductor earthed and 3 phase a.c. 3 wire system. (8)
15.(a)(i)Discuss any 1 kind of motor control circuit. (8)
(ii)A lamp has a uniform luminous intensity of 860 candelas in all directions. It is mounted seven m above ground. obtain the illumination at a point on the ground 12 m from the lamp post. (4)
(iii)Mention the general specifications of a generator and a transformer. (4)
Or
(b)(i)Explain laws of illumination. (8)
(ii)Give signs and symbols for ten electrical accessories. (8)

Earning:   Approval pending.