1.a) Derive the expression for inductance of a single phase two wire system.
b) Explain the advantages and disadvantages of bundled conductors. [15]
2.a) Explain why ABCD parameters are used for evaluating performance of a transmission line.
b) For a 3-φ 400 k v line A = D = 0.86, B = j130.2Ω, C = j0.002Ω obtain the regulation when the line is delivering 120 MVA at 0.8 pf tag. [15]
3. Derive the expressions for sending end parameters by Rigorous method. [15]
4.a) Using Bewleys lattice diagram, represent the voltage and current wave from of a bifurcated line.
b) Define surge impedance. Explain how it is evaluated for a overhead line and underground cable. [15]
5.a) Explain the skin and proximity effects on resistance of solid conductors.
b) A 3-φ , 220 k v, 50 Hz transmission line has equilateral triangular spacing of 2m side. The conductor diameter is 3.0cm. The air density factor and surface irregularity factor are 0.95 and 0.83 respectively. Find critical disruptive voltage and corona loss per kilometer. [15]
6.a) Explain how string efficiency can be improved for suspension insulation.
b) In a string of four suspension insulators, if the voltage across second and third units is 13.2 kv and 20kv respectively find the total working voltage of the string. [15]
7.a) Derive the expression for sag when the supports are at unequal heights.
b) Calculate the minimum sag permissible for a 160m span, 1 cm diameter copper conductor allowing a maximum tensile stress of 2000 kg /cm2. Assume a horizontal wind pressure of 4 kg/cm2. of projected area. Take specific gravity of copper as 8.9 gm/cm3. [15]
8.a) Explain about various of types of insulating materials used in underground cables.
b) Explain why underground cables are graded. How many types of grading are there in practice? [15]
b) Explain the advantages and disadvantages of bundled conductors. [15]
2.a) Explain why ABCD parameters are used for evaluating performance of a transmission line.
b) For a 3-φ 400 k v line A = D = 0.86, B = j130.2Ω, C = j0.002Ω obtain the regulation when the line is delivering 120 MVA at 0.8 pf tag. [15]
3. Derive the expressions for sending end parameters by Rigorous method. [15]
4.a) Using Bewleys lattice diagram, represent the voltage and current wave from of a bifurcated line.
b) Define surge impedance. Explain how it is evaluated for a overhead line and underground cable. [15]
5.a) Explain the skin and proximity effects on resistance of solid conductors.
b) A 3-φ , 220 k v, 50 Hz transmission line has equilateral triangular spacing of 2m side. The conductor diameter is 3.0cm. The air density factor and surface irregularity factor are 0.95 and 0.83 respectively. Find critical disruptive voltage and corona loss per kilometer. [15]
6.a) Explain how string efficiency can be improved for suspension insulation.
b) In a string of four suspension insulators, if the voltage across second and third units is 13.2 kv and 20kv respectively find the total working voltage of the string. [15]
7.a) Derive the expression for sag when the supports are at unequal heights.
b) Calculate the minimum sag permissible for a 160m span, 1 cm diameter copper conductor allowing a maximum tensile stress of 2000 kg /cm2. Assume a horizontal wind pressure of 4 kg/cm2. of projected area. Take specific gravity of copper as 8.9 gm/cm3. [15]
8.a) Explain about various of types of insulating materials used in underground cables.
b) Explain why underground cables are graded. How many types of grading are there in practice? [15]
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