Cochin University of Science and Techology (CUST) 2006 B.Tech Electrical and Electronics Engineering Power System - Question Paper

Power System (June 2006) EEE


1a. discuss how hydro-electric power plants are classified
b. Draw the schematic layout of a hydro electric plant
c. What do you understand by the term "available head"?
2a. describe the terms connected load, maximum demand and diversity factor
b. A domestic lighting installation having fifteen, 60W lamps is operated as follows:
5 lamps from 6pm till 8pm
10 lamps from 8pm till 10pm
6 lamps from 10pm till 12pm
i) Determine the connected load, the maximum demand, demand factor and the daily factor
ii) Also determine the improved load factor if a 2KW heater is used from 1pm till 5pm and a 2KW heater from 8pm till 11pm
3a. discuss the methods of equlizing the potential across every unit of a string insulator
b. A 3 phase 66KV transmission line is carried by strings of five supension insulators. The capacitance of every unit insulation to the capacitance relative to earth is 4:1. compute the potential across every unit and the string efficiency. presume that there is no leakage
4a. discuss the advantages of high transmission voltage
b. An overhead line with 2 poles 200m apart having a distance in level of 10ms. The conductor diameter is 2.0cm and weighs 2.3Kg/m length. compute the sag at the lower suport under the conditions if wind provides a pressure of 57.5Kg/square meter of the projected area. Factor of safety-4, Maximum tensile strength of the copper-4220Kg/sq.cm
5a. discuss the terms GMD and GMR in the computation of single phase transmission lines with composite conductors
b. A single phase overhead line 25KM long is to be constructed of conductors of 1.5cm diameter. compute the maximum spacing ranging from the conductors in order that loop inductance of conductor is no more than 0.0486H.
6a. discuss the various methods of grading of cables
b. Acable having conductor diameter of 1cm and an insulation thickness of 1.5cm is subjected to a pressure of 33KV. obtain the maximum field strength
7a. What is meant by radial and ring main distribution system?
b. A two wire d.c distributor cable is 2KM long and supplies loads of 100A,150A,200A and 50A situated 500m, 1000m, 1600m and 2000m from the feeding point A. The resistance of the conductor is 0.01 ohm per Km. compute voltage at every load point if a voltage of 300V is maintained at point A
8a. discuss the advantages of per-unit system
b. Draw a typical single line diagram of a power syatem. Mark the various components. Mention typical voltages of generation, transmission and distribution
9a. Derive the ABCD constants of a mediun transmission line and draw the phaser diagram assuming T-configuration.
b. discuss the Ferranti effect on transmission line
10a.Explain the advantages and limitations of HVDC and HVAC transmission
b. provide a brief account on Corona in HVDC lines
c. discuss any 2 methods of voltage control on transmission lines

Earning:   Approval pending.