Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 5th Sem New 2150908 Electrical Power System ? I Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? V (New) EXAMINATION ? WINTER 2019
Subject Code: 2150908 Date: 21/11/2019
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) Define electric power supply system. Draw a single line diagram of a typical
a.c. power supply system.
03
(b) Represent per unit model of generator, transmission line and load. 04
(c) List out the advantages and disadvantages of d.c transmission over a.c
transmission?
07
Q.2 (a) What is Skin effect and proximity effect? 03
(b) Explain function of insulator and discuss pin type insulator. 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) In a string of three units, the capacitance between each link pin to earth is
11 % of the capacitance of unit. Calculate the voltage across each unit and
the string efficiency when the voltage across the string is 33 KV.
07
Q.3 (a) Write shot note on bundle conductors. 03
(b) What do you mean by transposition of line? What is its effect on the
performance of the line?
04
(c) Derive an expression for the inductance per phase for a 3-phase overhead
transmission line when conductors are unsymmetrically placed but the line
is completely transposed.
07
OR
Q.3 (a) Derive an expression for electric potential at a charged single conductor. 03
(b) Calculate the inductance of each conductor in a 3-phase, 3-wire system
when the conductors are arranged in a horizontal plane with spacing such
that D31 = 4 m, D12 = D23 = 2 m. The conductors are transposed and have
a diameter of 2.5 cm.
04
(c) Derive the equation of Inductance of a single phase two wire system. 07
Q.4 (a) Explain self GMD and mutual GMD. 03
(b) Derive the equation of Capacitance of a single phase line 04
(c) A d.c. distributor AB is fed at both ends. At feeding point A, the voltage is
maintained at 230 V and at B, it is 235 V. The total length of the distributor
is 200 meters and loads are tapped off as under:
25 A at 50 m from A
50 A at 75 m from A
30 A at 100 m from A
40 A at 150 m from A
The resistance per kilometer of one conductor is 0.3 ohm. Calculate the
current in various sections of distributor and minimum voltage and the point
at which it occurs.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? V (New) EXAMINATION ? WINTER 2019
Subject Code: 2150908 Date: 21/11/2019
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) Define electric power supply system. Draw a single line diagram of a typical
a.c. power supply system.
03
(b) Represent per unit model of generator, transmission line and load. 04
(c) List out the advantages and disadvantages of d.c transmission over a.c
transmission?
07
Q.2 (a) What is Skin effect and proximity effect? 03
(b) Explain function of insulator and discuss pin type insulator. 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) In a string of three units, the capacitance between each link pin to earth is
11 % of the capacitance of unit. Calculate the voltage across each unit and
the string efficiency when the voltage across the string is 33 KV.
07
Q.3 (a) Write shot note on bundle conductors. 03
(b) What do you mean by transposition of line? What is its effect on the
performance of the line?
04
(c) Derive an expression for the inductance per phase for a 3-phase overhead
transmission line when conductors are unsymmetrically placed but the line
is completely transposed.
07
OR
Q.3 (a) Derive an expression for electric potential at a charged single conductor. 03
(b) Calculate the inductance of each conductor in a 3-phase, 3-wire system
when the conductors are arranged in a horizontal plane with spacing such
that D31 = 4 m, D12 = D23 = 2 m. The conductors are transposed and have
a diameter of 2.5 cm.
04
(c) Derive the equation of Inductance of a single phase two wire system. 07
Q.4 (a) Explain self GMD and mutual GMD. 03
(b) Derive the equation of Capacitance of a single phase line 04
(c) A d.c. distributor AB is fed at both ends. At feeding point A, the voltage is
maintained at 230 V and at B, it is 235 V. The total length of the distributor
is 200 meters and loads are tapped off as under:
25 A at 50 m from A
50 A at 75 m from A
30 A at 100 m from A
40 A at 150 m from A
The resistance per kilometer of one conductor is 0.3 ohm. Calculate the
current in various sections of distributor and minimum voltage and the point
at which it occurs.
07
2
OR
Q.4 (a) Describe briefly different types of d.c. distributors. 03
(b) Give the difference between a.c and d.c distribution. 04
(c) Derive an expression for line to neutral capacitance for a 3-phase overhead
transmission line when conductors are unsymmetrically placed but the line
is completely transposed
07
Q.5 (a) Give definition of per unit value. List out advantages of per unit system. 03
(b) Explain the PU representation of transformer. 04
(c) What should be the desirable characteristics of insulating materials used in
cables? Briefly describe some commonly used insulating materials for
cables.
07
OR
Q.5 (a) Give the classification 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) Explain the steady state model of synchronous machine with diagram 07
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This post was last modified on 20 February 2020