Seat No.: ________ Enrolment No.
___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER–IV (NEW) EXAMINATION – SUMMER 2021
Subject Code:3140914 Date:09/09/2021
Subject Name:Power System- I
Time:02:30 PM TO 05:00 PM Total Marks:70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.
MARKS
Q.1 (a) Define: Load factor, Demand factor and Diversity factor. 03
(b) Discuss present power generation scenario in Gujarat and India with 04
presenting proper data.
(c) Explain the steam power station with neat schematic diagram. 07
Also discuss advantages and disadvantages of steam power station.
Also write the points, which are considered during the site selection
of steam power plant.
Q.2 (a) Explain load curve and load duration curve with their importance. 03
(b) Compare steam power plant, hydro power plant and nuclear power 04
plant.
(c) Explain nuclear power plant with proper diagram. Also discuss advantages 07
and disadvantages of nuclear power plant.
OR
(c) A synchronous motor improves the power factor of a load of 200 kW 07
from 0.8 lagging to 0.9 lagging. Simultaneously the motor carries a
load of 80 kW. Find (i) the leading kVAR taken by the motor (ii) kVA
rating of the motor and (iii) power factor at which the motor operates.
Q.3 (a) Write merits and demerits of wind energy. Write the types of wind energy 03
system.
(b) Differentiate between horizontal and vertical axis wind turbine. 04
(c) What is power factor? Discuss the methods of power factor 07
improvement.
OR
Q.3 (a) Define tariff. Write the types of tariff. 03
(b) Discuss the comparison of overhead transmission system with 04
underground transmission system.
(c) Explain Photovoltaic cell for electrical power generation. 07
Write applications of solar energy.
Q.4 (a) What are the causes of low power factor? 03
(b) What is string efficiency? Explain methods of improving string 04
efficiency.
(c) Calculate the capacitance of a 100 km long 3-phase, 50 Hz overhead 07
transmission line consisting of 3 conductors, each of diameter 2 cm and
spaced 2.5 m at the corners of an equivalent triangle.
1
OR
Q.4 (a) Compare indoor substation with outdoor substation. 03
(b) Explain the methods of neutral grounding. 04
(c) Define substation. Explain the classification of substation considering 07
different ways.
Q.5 (a) Write types of cable considering voltage and insulating materials. 03
(b) What is a sag in overhead lines? Discuss the disadvantages of 04
providing too small or too large sag on a line.
(c) Derive an expression for the capacitance of a single phase overhead 07
transmission line.
OR
Q.5 (a) List out the main components of overhead lines. Also write the types 03
of insulators.
(b) Derive an expression for the loop inductance of a single phase line. 04
(c) Explain methods of distribution systems with necessary diagrams. 07
*************
2
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER–IV (NEW) EXAMINATION – SUMMER 2022
Subject Code:3140914 Date:06-07-2022
Subject Name: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.
4. Simple and non-programmable scientific calculators are allowed.
MARKS
Q.1 (a) Enlist various equipments used in substation. 03
(b) Explain pole mounted substation with suitable figure. 04
(c) Give comparison of steam power station and hydro power station. 07
Q.2 (a) Explain with neat sketch the construction of cables. 03
(b) What are the properties of insulating material for cables? name some 04
insulating materials used in cables
(c) Enlist different types of nuclear reactors. Explain working of 07
pressurized water nuclear reactor with suitable diagram.
OR
(c) A 3-phase transmission line being supported by three-disc insulators. 07
The potential across top unit and middle unit are 8 kV and 11kV
respectively. Calculated (i) the ratio of capacitance between pin and
earth to the self-capacitance of each unit (ii) the line voltage and (iii)
string efficiency.
Q.3 (a) Why starting motor is used in gas turbine power station? What is the 03
main difference between open cycle and combine cycle gas power
plant?
(b) Drawblock diagram of nuclear power station and explain working of 04
nuclear station including chain reaction.
(c) What is string efficiency? Derive its equation in case of 3-disc 07
string.Explain methods of improving string efficiency
OR
Q-3 (a) Compare AC and DC supply systems. 03
(b) What are the different methods of neutral grounding? Explain solid 04
grounding. State its advantage and disadvantages.
(c) With equation find out the volume of conductor in case of 3- 07
phase 3-wire system and 3-phase 4-wire system in overhead power
transmission.
Q-4 (a) What is tariff? Discuss three part tariff. 03
(b) What are the factors that affect the sag in the transmission line? 04
(c) Derive condition for most economic size of conductor in an 07
underground cable.
OR
Q-4 (a) Explain the disadvantages of low power factor. 03
(b) Differentiate between Horizontal and Vertical Axis Wind Turbine. 04
(c) What is solar photovoltaic system? Discus its major 07
components. Also state its applications.
Q-5 (a) Enlist the power factor improvement methods and describe any one 03
method.
(b) Explain the advantages of high voltage transmission line. 04
(c) Define the sag in overhead line. Derive the equation of sag in case of 07
When supports are at equal and unequal level. Also find the sag
during effect of wind and ice loading
OR
Q-5 (a) What do you mean by transposition of line? What is itseffect 03
on the performance of the line?
(b) Explain the effect of earth on capacitance. 04
(c) Explain the inductance of three phase transmission line. 07
****************
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER–IV (NEW) EXAMINATION – WINTER 2020
Subject Code:3140914 Date:03/03/2021
Subject Name:Power System- I
Time:02:30 PM TO 04:30 PM Total Marks:56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain with schematic arrangement of steam power station. 03
(b) Explain different types of turbines used in hydro power station. 04
(c) Give comparison of steam power station and hydro power station. 07
Q.2 (a) Explain with neat sketch the construction of cables. 03
(b) Explain advantages and disadvantages of gas turbine power plant. 04
(c) Enlist different types of nuclear reactors. Explainworking of 07
pressurized water nuclear reactor with suitable diagram.
Q.3 (a) Give comparison between conventional power plant and solar 03
thermal power plant.
(b) Draw block diagram of nuclear power station and explain working of 04
nuclear station including chain reaction.
(c) Write short notes on Doubly Fed Induction Generator (DFIG). 07
Q.4 (a) Compare AC and DC supply systems. 03
(b) What are the different methods of neutral grounding? Explain solid 04
grounding. State its advantage and disadvantages.
(c) With equation find out the volume of conductor in case of 3- 07
phase 3-wire system and 3-phase 4-wire system in overhead power
transmission.
Q.5 (a) What is tariff? Discuss three part tariff. 03
(b) What are the factors that affect the sag in the transmission line? 04
(c) Derive condition for most economic size of conductor in an 07
underground cable.
Q.6 (a) Explain the disadvantages of low power factor. 03
(b) Differentiate between Horizontal and Vertical Axis Wind Turbine. 04
(c) What is solar photovoltaic system? Discus its major 07
components. Also state its applications.
Q.7 (a) Enlist the power factor improvement methods and describe any one 03
method.
(b) Explain the advantages of high transmission line. 04
(c) Define the sag in overhead line. Derive the equation of sag in case of 07
When supports are at equal and unequal level. Also find the sag
during effect of wind and ice loading
Q.8 (a) Give comparison between overhead systems versus underground 03
transmission system.
(b) Explain the effect of earth on capacitance. 04
(c) Explain the inductance of three phase transmission line. 07
***********
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER–IV (NEW) EXAMINATION – WINTER 2021
Subject Code:3140914 Date:28/12/2021
Subject Name: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.
4. Simple and non-programmable scientific calculators are allowed.
MARKS
Q.1 (A) For a steam power station, Describe functions of: 03
1) Air Pre Heater
2) Cooling Tower
3) Economizer.
(B) Explain working principle of solar photovoltaic cell 04
(C) Draw and explain neat schematic arrangement of Hydro power 07
station and discuss function of its constituents.
Q.2 (A) Compare AC and DC supply system. 03
(B) What are the factors that affect the sag in transmission line? 04
(C) Develop various components of wind energy conversion system 07
with diagram.
OR
(C) Explain in detail about Synchronous condenser method for power 07
factor improvement.
Q.3 (A) Name the important components of an overhead transmission line. 03
Give reasons for unequal potential distribution over a string of
suspension insulators.
(B) Define and explain string efficiency. Can its value be equal to 04
100%? Justify your answer.
(C) Define the sag in overhead line. Derive the equation of sag in case 07
of When supports are at equal and unequal level. Also find the sag
during effect of wind and ice loading.
OR
Q.3 (A) Compare the merits and demerits of underground system versus 03
overhead system.
(B) What are the properties of insulating material for cables? Name 04
some insulating materials used in cables.
(C) What do you understand by grading of underground cables? List the 07
methods of grading and explain any one of them in detail.
Q.4 (A) What do you mean by the constants of an overhead transmission 03
line?
(B) Derive the equation of Capacitance of a single phase line. 04
1
(C) Calculate the inductance per phase per metre for a three-phase
double-circuit line whose phase conductors have a radius of 5·3 cm
with the horizontal conductor arrangement as shown in Fig. 07
OR
Q.4 (A) Explain self GMD and mutual GMD. 03
(B) Derive expression for capacitance for single core cable. 04
(C) What is electric supply system? Draw a single line diagram of a 07
typical a.c. power supply system.
Q.5 (A) Derive an expression for electric potential at a charged single 03
conductor.
(B) What is the effect of earth on Transmission line capacitance? 04
(C) Classify the sub-stations according to service requirement and 07
constructional features. Compare outdoor substation and indoor
substation
OR
Q.5 (A) Enlist various equipment’s used in substation 03
(B) What is neutral grounding? List the advantages of Neutral 04
grounding.
(C) Explain arc suppression coil earthing in detail. 07
2
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER–IV(NEW) EXAMINATION – WINTER 2022
Subject Code:3140914 Date:19-12-2022
Subject Name: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.
4. Simple and non-programmable scientific calculators are allowed.
MARKS
Q.1 (a) Define: i) load curve ii) load duration curve iii)base load 03
(b) Illustrate hydro power station with neat diagram. 04
(c) Solve an equation for most economical value of power factor which may 07
be attained by a consumer.
Q.2 (a) Show that in string of suspension insulators, the disc nearest to conductor 03
has the highest voltage across it.
(b) Explain construction and working of DFIG. 04
(c) In a 66 kV overhead line, there are three units in the string of insulators. 07
If the capacitance between each insulator pin and earth is 11% of self-
capacitance of each insulator, Calculate (i) the distribution of voltage
over 3 insulators and (ii) string efficiency.
OR
(c) Obtain an equation of sag in overhead lines. 07
i)When supports are at equal level.
ii) When supports are at unequal level.
iii)during effect of wind and ice loading
Q.3 (a) Define: Transposition of conductor & list out its advantages. 03
(b) Calculate the capacitance of a 100 km long 3-phase, 50 Hz overhead 04
transmission line consisting of 3 conductors, each of diameter 4 cm and
spaced 2·5 m at the corners of an equilateral triangle.
(c) Evaluate an expression for electric potential 07
(i) at a charged single conductor
(ii) at a conductor in a group of charged conductors
OR
Q.3 (a) Define: bundle conductor & list out its advantages. 03
(b) Derive an expression for the loop inductance of a single phase line. 04
(c) Deduce an expression for line to neutral capacitance for a 3-phase 07
overhead transmission line when the conductors are
(i) symmetrically placed
(ii) unsymmetrically placed but transposed
Q.4 (a) Compare the merits and demerits of underground system versus 03
overhead system.
(b) Explain desirable characteristics of insulating materials used in cables. 04
(c) Explain with neat sketch the construction of cables. 07
OR
Q.4 (a) Classify cables. 03
(b) Explain methods of grading. 04
1
(c) Determine condition for most economic size of conductor in an 07
underground cable.
Q.5 (a) Enlist various equipment’s used in substation 03
(b) Explain single bus bar arrangement in substation with neat diagram. 04
(c) Distinguish between a.c and d.c transmission. 07
OR
Q.5 (a) Define: Neutral grounding. List out advantages of neutral grounding. 03
(b) Explain transformer grounding. 04
(c) Evaluate an equation for the volume of conductor in case of 3- 07
phase 3-wire system and 3-phase 4-wire system in overhead power
transmission.
*************
