Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 5th Sem New 2150908 Electrical Power System ? I Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2150908 Date:20/11/2018
Subject Name:Electrical Power System ? I
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) What are the disadvantages of DC transmission System? 03
(b) Differentiate between feeder, distributor and service mains 04
(c) Compare the merits and demerits of underground versus overhead system 07
Q.2 (a) What is Skin effect and proximity effect? 03
(b) What are the factors that affect the sag in the transmission line? 04
(c)
Define the sag in overhead line. Derive the equation of sag in case of When supports
are at equal and unequal level. Also find the sag during effect of wind and ice
loading
07
OR
(c)
What is string efficiency? Derive its equation in case of 3 disc string. Explain
methods of improving string efficiency.
07
Q.3 (a) Give comparison conductor material in overhead system. 03
(b) Define and explain primary and secondary distribution system with single line
diagram
04
(c) With equation find out the volume of conductor in case of 3-phase 3-wire
system and 3-phase 4-wire system in overhead power transmission
07
OR
Q.3 (a) Explain self GMD and mutual GMD. 03
(b) Give classification of distribution systems 04
(c) Name the different types of insulators used in transmission system. Explain Any
one in brief with diagrams.
07
Q.4 (a) What are the advantages of per unit system? 03
(b) What are the properties of insulating material for cables? name some insulating
materials used in cables
04
(c) Two generators G1 and G2 are connected in parallel to a bus bar.
Generator G1:10MVA,13.2KV,reactance=15%
Generator G2:15MVA,13.2KV,reactance=15%
The generators G1 and G2 feed supply to two motors M1 and M2
respectively.
Motor M1:8MVA,12.5KV,reactance=20%
Motor M2:12MVA,12.5KV,reactance=20%
Assuming base quantities as 50MVA and 13.8KV.Draw reactance diagram.
07
OR
Q.4 (a) What is the effect of earth on Transmission line capacitance? 03
(b) What do you mean by transposition of line? What is i t ?s effect on the
performance of the line.
04
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2150908 Date:20/11/2018
Subject Name:Electrical Power System ? I
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) What are the disadvantages of DC transmission System? 03
(b) Differentiate between feeder, distributor and service mains 04
(c) Compare the merits and demerits of underground versus overhead system 07
Q.2 (a) What is Skin effect and proximity effect? 03
(b) What are the factors that affect the sag in the transmission line? 04
(c)
Define the sag in overhead line. Derive the equation of sag in case of When supports
are at equal and unequal level. Also find the sag during effect of wind and ice
loading
07
OR
(c)
What is string efficiency? Derive its equation in case of 3 disc string. Explain
methods of improving string efficiency.
07
Q.3 (a) Give comparison conductor material in overhead system. 03
(b) Define and explain primary and secondary distribution system with single line
diagram
04
(c) With equation find out the volume of conductor in case of 3-phase 3-wire
system and 3-phase 4-wire system in overhead power transmission
07
OR
Q.3 (a) Explain self GMD and mutual GMD. 03
(b) Give classification of distribution systems 04
(c) Name the different types of insulators used in transmission system. Explain Any
one in brief with diagrams.
07
Q.4 (a) What are the advantages of per unit system? 03
(b) What are the properties of insulating material for cables? name some insulating
materials used in cables
04
(c) Two generators G1 and G2 are connected in parallel to a bus bar.
Generator G1:10MVA,13.2KV,reactance=15%
Generator G2:15MVA,13.2KV,reactance=15%
The generators G1 and G2 feed supply to two motors M1 and M2
respectively.
Motor M1:8MVA,12.5KV,reactance=20%
Motor M2:12MVA,12.5KV,reactance=20%
Assuming base quantities as 50MVA and 13.8KV.Draw reactance diagram.
07
OR
Q.4 (a) What is the effect of earth on Transmission line capacitance? 03
(b) What do you mean by transposition of line? What is i t ?s effect on the
performance of the line.
04
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2
(c) A 2-wire d.c.distributor AB is 300m long. It is fed at point A .The various
loads and their positions are given below:
At point Distance from A
in amperes in meters
Concentrated
load in amperes
C 40 30
D 100 40
E 150 100
F 250 50
If the maximum permissible voltage drop is not to exceed 10V, Find the
cross sectional area of the distributor. Take ?= 1.7 8? 10
-8
?m.
07
Q.5 (a) Explain with neat sketch the construction of cables. 03
(b) A single ?core cable has a conductor diameter of 1c.m. and insulation
thickness of 0.4cm. If the specific resistance of insulation is 5?10
14
?-cm,
calculate the insulation resistance for a 2km length of cable.
04
(c) In a 33KV over headline, there are three units in the string of insulators. If
the capacitance between each insulator pin and earth is 11% of self
capacitance of each insulator, find (i) the distribution of voltage over 3
insulators and (ii) string efficiency.
07
OR
Q.5 (a) Write shot note on bundle conductors. 03
(b) What are the methods of improving string efficiency? Explain any one in
brief.
04
(c) Explain the steady state model of synchronous machine with diagram. 07
*************
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This post was last modified on 20 February 2020