Total No. of Pages : 02
Total No. of Questions : 09
B.Tech.(EE/Electrical & Electronics/Electronics & Electrical) (2011 Onwards)/ (Electrical Engineering & Industrial Control) (2012 Onwards)
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(Sem.-4)
POWER SYSTEM-I (TRANSMISSION AND DISTRIBUTION)
Subject Code : BTEE-405
M.Code: 57107
Time: 3 Hrs.
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Max. Marks : 60
INSTRUCTION TO CANDIDATES :
- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.
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SECTION-A
1. Answer briefly :
- What is the significance of ABCD parameters?
- What is skin effect and methods to reduce skin effect?
- Why busbars in EHV substations are hollow bars, what is the reason?
- What is ACSR cable and where we use it?
- What will happen when power factor is leading in distribution of power?
- What are the advantages of transposition of power lines?
- What are the limitations of Kelvin's Law?
- What are the common causes of failure of underground cable?
- What is the purpose of insulator?
- What is a belted-cable?
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SECTION-B
2. Derive the expression for the capacitance of a single-core cable.
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3. Derive and draw the receiving-end power circle diagram in terms of general circuit constants.
4. What is Ferranti effect? Deduce an expression for the voltage rise of an unloaded line.
5. A 500V, 2-core feeder, 0.8km long is required to supply a constant load of 100kW. The cost of the cable including installation charges is Rs. (6a+1.3) per meter, where a is the cross section area of each feeder in cm². Interest and depreciation is total 10%. Determine the most economical size. The cost of energy is 12 paise per unit. Specific resistance of copper is 1.75 × 10?6 O/cm² cross sectional area and 1cm long.
6. What are the advantages and disadvantages of oil filled cables?
7. Determine the overall diameter of a single-core cable and its most economical diameter when working on a three-phase 275kV system. The maximum permissible stress in the dielectric is not to exceed 15kV/mm.
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8. A 15000 kVA is received at 33kV at 0.85 power factor lagging over an 8 km three-phase overhead line. Each line has R = 0.29O/km, and X1= 0.65O/km. Calculate
- The voltage at the sending end
- The power factor at the sending end
- The regulation, and
- The efficiency of the transmission line.
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9. What is the effect of earth on line capacitance? Explain the method of images to calculate the capacitance of
- Two-wire single-phase line
- Single circuit three phase transposed line.
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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This download link is referred from the post: PTU B.Tech 4th Semester Last 10 Years 2009-2019 Previous Question Papers|| Punjab Technical University
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