University of Mumbai 2007-5th Sem B.E Electrical and Electronics Engineering Elements of Power System - exam paper

(3 Hours)

[Total Marks : 100

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.B.: (1) Question No. 1 is compulsory. %

(2)    Attempt any four questions from remaining six questions.

(3)    Assume suitablefiataiLnecessary.    * r~

a    1 try J Is

^Explain:- ⁰

(a)    Tuned Power Lines.    I y f ^f '

(b)    Step Potential and Touch Potential.

(c)    Method of Neutral Grounding.

(d)    Arcing Grounds.

(a)    Derive the capacitance of a three-phase line with unsymmetrical spacing. What is 12 the effect of earth on capacitance ?

(b)    Find the capacitance per phase per Km, capacitive reactance per phase, charging 8 current and total charging mega volt-ampere of the following line :

V = 220kV, 50 Hz, Length = 250 km, Spacing = 6-5 m x = 6-5mx12m, Conductor Radius = 1-96 cm.

(a)    Explain Feranti effect.

(b)    Explain in brief the current rating of a cable.

(a)    Describe the methods to improve string-efficiency.

(b)    Describe the different method of voltage-control.

(a)    Find the A, B, C, D constants of medium length transmission line, represented by 10 nominal n model. Draw the phasor diagram.

(b)    Explain in detail the measurement of earth resistance and soil resistivity.    10

(a) Single tine diagram of a system is shown in figure. Draw the reactance diagrams 15 and indicate the reactance in per unit:

90 MVA, 11kV, X =25%

100 MVA, 10/132 kV, X = 6%

Composed of three 1-$ units each rated at 30 MVA, 66/10 kV_t X = 5%

50 MVA, 10 kV, X = 20%

40 MVA, 10 kV X = 20%

Line reactance = 100 OHM

Consider generator rating as base value.

(b) Define and explain 'Self and Mutual GMD'.    5

(a)    Explain skin effect.

(b)    Explain significance of transposition.

(c)    Advantage of per unit system.

(d)    Explain bundled conductor.

20

Attachment: university-of-mumbai-2007-b-e-electrical-and-electronics-engineering-51216-1.pdf

Earning:   Approval pending.