P.T.O. 12102111223 Hours/ 100 MarksInstructions : (1) All questions are compulsory.(2) Answer each next main Question on a new page.(3) Illustrate your answers with neat sketches wherevernecessary.(4) Figures to the right indicate full marks.(5) Assume suitable data, if necessary.(6) Use of non-programmable Electronic Pocket Calculator ispermissible.(7) Mobile Phone, Pager and any other Electronic Communicationdevices are not permissible in Examination Hall.(8) Use of steam tables, logarithmic, Molliers chart is permitted.MARKSI. A)Attempt any six of the following : (62=12)1) State the necessity of transmission of electricity.2) State the standard transmission voltages in India.3) Draw single line diagram of A. C. supply system.4) What is corona ? Also state the factors affecting corona.5) Define voltage regulation of a transmission line.6) What is skin effect ?7) Write down any four properties of line support.8) Classify transmission lines. Also state the length of line and voltage valuein each case.B)Attempt any two of the following : (24=8)1) What are the methods to improve string efficiency ? Explain each methodin detail.2) What are the reasons for the failure of insulators ? Explain any four pointsin brief.3) With the help of diagram, explain the concept of transposition of conductors.Seat No.12102 -2- MARKSII. Attempt any four of the following : (44=16)1) Explain Ferranti effect and proximity effect related to transmission lines.2) State and explain the reasons for adoption of EHVAC transmission (Any fourimportant points).3) Classify distribution system by taking three different basic factors. Also drawthe simple arrangement for radial distribution system.4) What are the requirements of a good distribution system ? Explain each pointin detail.5) Compare A.C. distribution with d.c. distribution system and write down any siximportant points.6) Describe the effect of load p.f. on performance of transmission line.III. Attempt any two of the following : (28=16)1) a)Define string efficiency. 2b)A 3-phase overhead transmission line is being supported by three discinsulators. The potentials across top unit (ie. near to the tower) and middleunit are 8 kV and 11 kV respectively. Calculatei) The ratio of capacitance between pin and earth to the self capacitance ofeach unitii) The line voltage andiii) String efficiency. 62) a)What is sag in overhead lines ? 2b)A transmission line has a span of 150 m between level supports. The conductorhas a cross-sectional area of 2cm2. The tension in the conductor is 2000 kg.If the specific gravity of the conductor material is 9.9 gm/cm2 and wind pressur

eis 1.5 kg/m length, calculate the sag. Also calculate the value of vertical sag.63) Draw nominal network for medium transmission line. Draw its vector diagramand state its ABCD constants.MARKS -3- 12102IV. Attem t any two of the following : (28=16)1) A single hase overhead transmission line delivers 1100 kW at 33 kV at .8 .f.lagging. The total resistance and inductive reactance of the line are 10 ohm and15 ohm res ectively. Determine :a) Sending end voltageb) Sending end .f. andc) Transmission efficiency.2) Write down any four advantages and any four limitations of HVDC transmissionsystem.3) A single hase a.c. distributor AB 300 metres long is fed from end A and isloaded as under ;i) 100 A at .707 .f. lagging 200 m from oint A.ii) 200 A at .8 .f. lagging 300 m from oint A.The total resistance and reactance of the distributor is 0.2 and 0.1perkilometre. Calculate the total voltage drop in the distributor. The load p.f. referto the voltage at the far end. Refer Fig. a.Fig. aV. Attempt any four of the following : (44=16)1) Describe ring main system of distribution with diagram.2) ith a neat labelled diagram show the various parts of a 3-conductor cable.3) Draw and discuss H type cables in detail.12102 -4- 4) rite down the functions of following elements of a substation :a) CB b) relaysc) Lightning arrester d) isolators.5) Discuss briefly the design considerations for distribution system.VI. Attempt any four of the following : (44=16)1) Calculate the regulation and efficiency of a medium transmission line usingEnd condenser method ?2) hat is substation ? hat are the important points which must be kept in viewwhile laying out a substation ?3) hat is indoor substation ? Draw its key diagram.4) hat are the desirable properties of insulating material for cable ? Also statetwo examples for insulating material for cable.5) ith the help of diagram, explain the system for laying of underground cables.6) Compare indoor and outdoor substations by taking the following factors :a) Space requiredb) Time for eretionc) Capital costd) Maintenancee) Fault locationf) Future expansion.__________________MARKS