Download PTU B.Tech 2020 March EE 3rd Sem Power System I (Transmission And Distribution) Question Paper

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Roll No.

Total No. of Pages : 02

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Total No. of Questions : 09

B.Tech.(EE) PT (Sem.-3)

POWER SYSTEM - | (Transmission & Distribution)

Subject Code : BTEE-405

M.Code : 72165

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Time : 3 Hrs. Max. Marks : 60

INSTRUCTION TO CANDIDATES :

1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.

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SECTION-A

1. Write briefly :
   1. State importance of voltage regulation in transmission lines.
   2. Differentiate between hollow and bundle conductors.
   3. Mention advantages of suspension insulators over pin type insulators.
   4. What is meant by dielectric loss in cables?

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   5. Give advantage of series and shunt capacitors in transmission lines.
   6. Why surge impedance loading increase with increase in voltage level?
   7. Mention advantages and disadvantages of underground cables.
   8. Give importance of synchronous phase modifiers.
   9. List factors, that limit maximum transfer capability in transmission line.

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   10. Why phase shift is kept low for transmission of power for large distances?

SECTION-B

2. Explain the concept of self GMD and mutual GMD for evaluating inductance of transmission lines.
3. Deduce an expression for voltage regulation of a short transmission line, giving the vector diagram.

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4. A string of 5 insulators is connected across a 100 kV line. If the capacitance of each disc to earth is 0.1 of the capacitance of the insulator, calculate:
   1. The distribution of voltage on the insulator discs.
   2. The string efficiency.
5. Describe with a neat sketch, the construction of a 3-core belted type cable. Discuss the limitations of such a cable.
6. Explain procedure to draw the receiving end circle diagram for a long transmission line based on ABCD constants.

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SECTION-C

7. 1. Three conductors of a 3-phase line are arranged at the corners of a triangle of sides 2 m, 2.5 m and 4.5 m. Find the inductance per km of the line when conductors are regularly transposed. The diameter of each conductor is 1.24 cm.
   2. State and prove Kelvin’s law for size of conductor for transmission. Discuss its limitations.
8. 1. A 3-phase, 50Hz, 150 km line has a resistance; inductive reactance and capacitive shunt admittance of 0.1 ©, 0.5 Q and 3x10°®S per km per phase. If the line delivers 50 MW at 110 kV and 0.8 p.f lagging; determine the sending end voltage and current. Assume a nominal ©t circuit for the line.

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   2. Describe briefly various methods of laying underground cables.
9. Write short notes on the following :
   1. Compensation of transmission lines
   2. Radial and mesh distribution networks

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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.

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