University of Mumbai 2012-4th Sem B.E Electrical Engineering S.E( ) ELEMENT OF POWER SYSTEM (ELECTRICAL ENGG.) - Question Paper
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,B.: (1) Question No. 1 is compulsory.
(2) any four questions out of remaining six questions.
(3) Assume required data.
1. Ja) Draw typical AC supply system.
(b) What is skin effect ?
-(c) Write advantages of per unit system.
*(d) Explain and draw H-type cable.
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2. (a) The arrangement of conductors of a single phase transmission line is shown 10 in figure wherein the forward circuit is composed of three solid wires 2-5 mm in radius and the return circuit of two-wires of radius 5 mm placed symmetrically with respect to the forward circuit. Find the inductance of each side of the line and that of complete line.
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(b) Explain in brief Grading of cable.
(a) What is cross-arms and line supports. An overhead line, over a river crossing 10 is supported by two towers'50 m and 80 m above water level. The horizontal span is 300 m. If the weight of conductor is 8-28 N/m and the tension in the conductor is 19620 N. Find the height of mid point of the line above water
level.
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(b) Derive Inductance of a single-phase two wire line.
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L (a) What Is Bundtedconductors ? Rnd the inductive reactance in ohms per kilometer at 50 Hz of a three-phase bundled conductor line with two conductors per phase as shown in figure. All the conductors are ACSR with radii o 1 -725 cm.
(b) What is string efficiency and methods of improving string efficiency ?
5. (a) Calculate ABCD parameters for nominal tc circuit and also draw phasor diagram for same. Using.jnominal method, find the sending end voltage and voltage regulation of a 250 km, three phaseT50 Hz, Transmission line delivering
25 MVA 0-8 fagging power factor to balanced load at 132 kV. The fine conductors are spaced equilaterally 3 m apart. The conductor resistance is 0-11 Q/km and its effective diameter is 1-6 cm. Neglect leakage.
(b) What is difference between step voltage and touch Voltage.
, 6. (a). Derive capacitance of a Three-phase line with equilateral spacing. A Three- phase 50 Hz transmission line has flat horizontal spacing with 3-5 m between adjacent conductors. The conductors are No. 210 hard-drawn seven strand copper (outside conductor diameter = 1-05 cm). The voltage of line is 110 kV. Rnd the capacitance to neutral and the charging current per kilometer of fine,
(b) Explain with advantages and disadvantages of Solid Grounding and Resistance Grounding.
7. Write short notes on
(a) Types of insulators
(b) Surge Impedance loading
(c) Transposition in Transmission line.
(d) Effect of earth on capacitance of a single-phase line.
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