Ps i Prelim Question Paper 2014_15
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STES's NBN SINHGAD TECHNICAL INSTITUTES CAMPUS NBN SINHGAD SCHOOL OF ENGINEERING, PUNE-41 SEM-II Prelim Exam S.E. (Electrical) P0WER SYSTEMS I (Year-2014-15) Max Marks: 30 Q. 1 (a ) Derive the expression for line to neutral capacitance of a three-phase overhead transmission line with unsymmetrical spacing of conductors. Assume complete transposition. (0 7) (b ) A single-phase line is having 2 single stranded conductor and radius 0.328 cm. The conductors are spaced 4 m apart and 8 m above the ground. Calculate the capacitance to neutral per km: (1) Considering earth’s effect (2) Neglecting earth’s effect. (0 8) OR Q. 2 (a ) Explain the “Method of Images” in determining the effect of earth on the calculation of capacitance. (0 4) (b ) Derive the equation for capacitance per km of a single- phase overhead transmission line having distance ‘D’ between the conductors and radius of each conductor ‘r’. (0 5) (c ) A 3-phase, 110 kV, 50 Hz overhead line conductors are placed in a horizontal plane. The conductor diameter is 1.5 cm. If the line length is 100 km, assuming complete transposition of the line, calculate: (1) Capacitance per phase (line to neutral) (2) Charging current per phase. (0 6) Q. 3 (a ) Give classification of transmission lines based on length. Explain the influence of power factor on the performance of a transmission line. (0 7) (b ) A balanced 3-phase load of 30 MW is supplied at 132 kV, 50 Hz and 0.85 p.f. lagging by means of a transmission line. The series impedance of a single conductor is (20 + j52) Ω and total phase neutral admittance is 315 × 10–6 (0 8)
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Transcript of Ps i Prelim Question Paper 2014_15
STES's NBN SINHGAD TECHNICAL INSTITUTES CAMPUSNBN SINHGAD SCHOOL OF ENGINEERING, PUNE-41
SEM-II Prelim Exam S.E. (Electrical)
P0WER SYSTEMS I (Year-2014-15) Max Marks: 30
Q.1(a)Derive the expression for line to neutral capacitance of a three-phase overhead transmission line with unsymmetrical spacing of conductors. Assume complete transposition.(07)
(b) A single-phase line is having 2 single stranded conductor and radius 0.328 cm. The conductors are spaced 4 m apart and 8 m above the ground. Calculate the capacitance to neutral per km:(1) Considering earths effect(2) Neglecting earths effect.(08)
OR
Q.2(a)Explain the Method of Images in determining the effect of earth on the calculation of capacitance.(04)
(b) Derive the equation for capacitance per km of a single-phase overhead transmission line having distance D between the conductors and radius of each conductor r.
(05)
(c)A 3-phase, 110 kV, 50 Hz overhead line conductors are placed in a horizontal plane. The conductor diameter is 1.5 cm. If the line length is 100 km, assuming complete transposition of the line, calculate:
(1) Capacitance per phase (line to neutral)(2) Charging current per phase.
(06)
Q.3(a)Give classification of transmission lines based on length. Explain the influence of power factor on the performance of a transmission line.(07)
(b) A balanced 3-phase load of 30 MW is supplied at 132 kV, 50 Hz and 0.85 p.f. lagging by means of a transmission line. The series impedance of a single conductor is (20 + j52) and total phase neutral admittance is 315 106 S. Use T-method to find: (1) A, B, C, D constants of the line(2) Sending end voltage (line-to-line).(08)
OR
Q.4(a)Express the relationship for the sending end voltage and current in terms of receiving end voltage and current for a medium length transmission line with Nominal method of representation. Evaluate the generalized circuit constants. Draw the phasor diagram.
(08)
(b) An 11 kV, 3-phase transmission line has R = 1.5 and reactance 4 per phase.Calculate percentage regulation and efficiency of the line when total load of 5000 kVA at 0.80 p.f. lagging is supplied at 11 kV at the distance end.(07)
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