VIDYARTHIPLUS.COM
QUESTION BANK
SUBJECT CODE/NAME: EE1302-TRANSMISSION
& DISTRIBUTION ENGINEERING
YEAR / SEM : III / V
UNIT- I
TRANSMISSION SYSTEM
1.
What
is meant by power supply system?
2.
What
is meant by Transmission and Distribution system?
3.
What
are the different types of Power supply system?
4.
What
are the various components of power supply system?
5.
What
are the different types of power plants?
6.
What
are the different operating voltages used for generation, primary and secondary
transmission in AC power supply systems in India?
7.
Define
– Feeder, distributor and service mains.
8.
List
the advantages of high voltage transmission.
9.
State
Kelvin’s law.
10.
What
are the limitations of Kelvin’s law?
11.
Define
– Break-even distance.
12.
List
the disadvantages of DC transmission.
13.
List
the different types of DC links.
14.
Define
– Short Circuit Ratio (SCR)
15.
What
are the limitations of high voltage transmission?
16.
List
the various types of distribution systems.
17.List the different types of
distribution systems based on connection
18. What are the different components
of a distribution system?
20.
What
are the limitations of HVDC system?
21.
List
the two merits of HVDC system
22.
List
the HVDC systems present and which are in operation in India.
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23.
List
the applications of HVDC system.
24.
List
the advantages of EHVAC transmission system.
25. What
is the need of load dispatch centres? Where are the LDC's available in Tamil
Nadu?
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PART-B
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1.(i)Discuss
various types of HVDC links.
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(8)
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(ii)List out the
main components of a HVDC system.
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(8)
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2.(i) Draw and
explain the structure of modern power systems with typical
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(13)
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voltage levels.
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(ii)What is the
highest voltage level available in India?
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(3)
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3.
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(i).Explain the effect of high
voltage on volume of copper and on efficiency. (8)
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(ii) Explain why
the transmission lines are 3 phase 3-wire circuits while
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(8)
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distribution lines are 3 phase
4-wire circuits.
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4.
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(i) Draw the model power system with
single line representation. Show its
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(6)
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essential constituent sections.
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(ii) What are the
AC transmission and distribution level voltages we have in
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India?
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(4)
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(iii) What are the different kinds
of DC links? Draw relevant diagrams.
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(6)
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5.
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(i)Explain why EHV
transmission is preferred? What are the problems involved
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in EHV AC transmission?
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(8)
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(ii) With neat schematic, explain
the principle of HVDC system operation.
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(8)
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6.
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Explain about FACTS with neat
diagram
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(16)
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7.
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Explain TCSC and SVS systems
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(16)
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8.
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Explain with neat diagram about
STATCOM and UPFC
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(16)
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9.
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(i) Compare EHVAC and HVDC
transmission
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(8)
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(ii) Explain the applications of
HVDC transmission system
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(8)
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UNIT- II
TRANSMISSION LINE
PARAMETERS
PART-A
1.
Define
Skin effect.
2.
What
is meant by proximity effect?
3.
List
out the advantages of double circuit lines.
4.
Define
- Self and mutual – G.M.D.
Self GMD (GMR):
5.
What
is meant by inductive interference?
6.
What
is transposition of conductors?
7.
State
why transposition of line conductors are needed?
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EE1302 TRANSMISSION AND DISTRIBUTION ENGINEERING
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8.
List
the advantages of bundled conductors.
9.
What
are the factors that affect the skin effect?
10.
Why
the effective resistance is more than the static resistance of a transmission
line?
11.
Why
does a transmission lines have resistance, inductance, and capacitance?
12.
List
the factors that governing the capacitance of a transmission line.
13.
What
is ACSR conductor?
14.
What
is fictitious conductor radius?
15.
State
the advantages of double circuit line over single circuit line.
16.
Define
unsymmetrical spacing.
17.
Define
symmetrical spacing.
18.
Define
capacitor.
19.
What
do you understand by inductive interference?
PART-B
1.
From the fundamentals derive an expression for inductance of a single
phase
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transmission system.
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(16)
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2.
Derive an expression for capacitances of a single phase transmission system
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and discuss the effect of earth on
capacitance with suitable equation.
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(16)
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3. (i) Derive an expression for
inductance of a single-phase overhead line.
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(8)
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(ii) A conductor is
composed of seven identical copper strands each having a
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radius r. Find the self-GMD of the
conductor.
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(8)
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4.
i) Derive an expression for the
capacitance between conductors of a single
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phase overhead line.
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(8)
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ii) Find the capacitance between the
conductors of a single-phase 10 km long line.
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The diameter of
each conductor is 1.213cm. The spacing between conductors is
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1.25m. Also find the capacitance of
each conductor neutral.
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(8)
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5. i) Derive the
expression for inductance of a two wire 1Φ transmission line
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(8)
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ii) Derive the expression for
capacitance of a 1Φ transmission line
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(8)
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6. i)What are the
advantages of bundled conductors?
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(4)
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ii)
Derive the expression
for capacitance of
a double circuit
line for hexagonal
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spacing.
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(8)
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iii) Why is the
concept of self GMD is not applicable for capacitance?
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(4)
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7.
i) Explain clearly the skin effect and the proximity effects when referred to
overhead lines. (8)
ii)
Write a short note on the inductive interference between power and
communication lines. (8)
8.
i) Derive the expression for the capacitance per phase of the 3 Φ double
circuit line flat vertical spacing with transposition. (8)
ii)
A 3 Φ overhead transmission line has its conductors arranged at the corners of
an equilateral triangle of 2m side. Calculate the capacitance of each line
conductor per km. Given the diameter of each conductor is 1.25cm. (8)
9. Find the capacitance per km per
phase of a 3Φ line arrangement in a horizontal
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plane spaced 8 metres apart. The
height of all conductors above the earth is 13
metres.
The diameter of each conductor is 2.6 cm. the line is completely transposed and
takes the effect of ground into account. (16)
10. Discuss the concept of GMR and GMD in the calculation
of transmission line inductance. (16)
UNIT- III
MODELLING AND PERFORMANCE
OF TRANSMISSION LINES
PART- A (2 MARKS)
1.
Classify
overhead transmission lines.
2.
Define
transmission efficiency.
3.
What
is a transmission line?
4.
List
out the common methods of representation of medium transmission lines.
5.
Define
regulation of power transmission line.
6.
What
is tuned power line?
7.
What
is surge impedance loading or natural loading?
8.
What
are the voltages regulating equipments used in transmission systems?
9.
What
is attenuation in a power transmission line?
10.
What
are the units of generalized constants of a transmission line?
11.
What
is the range of surge impedance for an overhead transmission line?
12.
What
is a power circle diagram?
13.
What
is meant by the receiving end power circle diagram?
14.
What
is Ferranti effect?
15.
What
is the cause of Ferranti effect?
16.
Define
corona.
17.
What
is local corona?
18.
Define
critical disruptive voltage.
19. What
are the methods adopted to reduce corona?
20.
Is
there any advantage on corona?
21.
What
is the use of power circle diagram?
22.
What
are the causes of voltage drop and line loss in a transmission line?
23.
What
are the advantages of using series compensation?
24.
What
are the main disadvantages of corona?
25.
Define
sag.
26.
What
is stringing chart?
27.
What
are the uses of stringing chart?
28.
What
are the factors which govern the performance of a transmission line?
29.
What
is the reason for sag in transmission line?
PART-B
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EE1302 TRANSMISSION AND DISTRIBUTION
ENGINEERING
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1. Determine the efficiency and
regulation of a 3phase, 100Km, 50 Hz
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transmission
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line
delivering 20 MW at a power factor of 0.8 lagging and 66 kV to a balanced
load.
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The conductors are of copper, each
having resistance
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0.1 Ω
/ Km, 1.5 cm outside dia, spaced equilaterally 2 metres between centres. Use
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nominal T method.
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(16)
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2. A three phase 5 km
long transmission line, having resistance of 0.5 Ω / km and inductance
of 1.76mH/km is delivering power at 0.8 pf lagging. The receiving end voltage
is 32kV. If the supply end voltage is 33 kV, 50 Hz, find line current,
regulation
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and efficiency of the transmission
line.
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(16)
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3. Derive the
expressions for sending end voltage in nominal T method and end
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(16)
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Condenser method.
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4. i) What is an equivalent p circuit of long
line? Derive expression for parameters of this circuit in terms of line
parameters.
(8)ii) A 50Hz transmission line 300 km long total series
impedance of 40+j25 Ω and total shunt admittance of 10 mho. The 220 Kv with 0.8 lagging power
factor. Find the
sending end voltage, current,
power and power factor using nominal p
method.(8)
5. i) Define regulation of a transmission
line and derive the approximate expression for
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the regulation of a
short transmission line.
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(8)
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ii) What is corona
loss? How do you determine this loss?
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(8)
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6. A 220kV, 3Φ transmission line has an
impedance per phase of (40+j200)Ω and an admittance of
(0+j0.0015) mho. Determine the sending end voltage and sending end current when
the receiving end current is 200 A at 0.95 pf lagging. Use nominal T method. (16)
7. Determine the efficiency and regulation of
a three phase 200 km, 50Hz transmission line delivering 100MW at a pf of 0.8
lagging and 33kV to a balanced load. The conductors are of copper, each having
resistance 0.1 Ω/km, and 1.5cm outside dia, spaced equilaterally 2m
between centres. Neglect leakage reactance and use nominal
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T and π methods.
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(16)
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8. i) Explain the
Ferranti effect with
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aphasor diagram and its causes.
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(6)
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ii) Explain the classification of
lines based on their length of transmission.
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(4)
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iii) What are ABCD constants.
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(6)
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UNIT- IV
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INSULATORS AND CABLES
PART- A ( 2 MARKS)
1.
What
is the purpose of insulator?
2.
What
are the important characteristics that an overhead line insulator must provide?
3.
What
are the materials used for overhead line insulators?
4.
List
out various types of insulators used for overhead transmission lines.
5.
Mention
the advantages of the pin type insulator.
6.
What
are the main causes for failure of insulators?
7.
What
are the different tests that are conducted on an insulator?
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EE1302 TRANSMISSION AND DISTRIBUTION ENGINEERING
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8. Write short notes on
puncture test.
9. Define impulse ratio.
10. What are the routine
tests conducted on insulators?
11. What are the
performance tests conducted on insulators?
12. What are the merits
of under ground cables?
13. What is meant by
efficiency of an insulator string?
14. What is the main
purpose of bedding?
15. What are the common
materials used for insulation?
16. What is the main
purpose of armouring?
17. What is serving?
18. What is dielectric
stress?
19. What is grading of
cables?
20. What are the main
advantages of suspension type insulators over pin type ones?
21. What are the methods
for improving string efficiency?
22. Name the two methods
of locating cable faults.
23. State two types of
faults in a cable.
PART-B
1.Discuss any two methods to increase the
value of string efficiency, with suitable
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sketches.
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(16)
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2.Explain any two
methods of grading of cables with necessary diagrams.
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(16)
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3.
i)
What are different methods to improve string efficiency of an insulator? (8)
ii)
In
a 3-unit insulator, the joint to tower capacitance is 20% of the capacitance of
each unit. By how much should the capacitance of the lowest unit be increased
to get a
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string efficiency
of 90%. The remaining two units are left unchanged.
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(8)
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4. i)Derive the expression for insulator resistance,
capacitance and electric stress
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in a single core cable. Where is the
stress maximum and minimum?
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(8)
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ii) A single core 66kv cable working on 3-
phase system has a conductor diameter of 2cm and sheath of inside diameter
5.3cm. If two inner sheaths are introduced in such a way that the stress varies
between the same maximum and minimum in the three layers find:
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a)
position of inner sheaths
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b)
voltage on the linear sheaths
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(8)
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c) maximum and minimum stress
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5.i)Draw the
schematic diagram of a pin type insulator and explain its function(8)
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ii) A 3 phase overhead transmission
line is being supported by three disc
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insulators. The potential across top
unit (i.e. near the tower) and the middle
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unit are 8kV and 11kV respectively.
Calculate,
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a)
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The ratio
of capacitance between
pin and earth
to the self
capacitance of
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each unit
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(4)
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b)
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Line Voltage
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(2)
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c)
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String Efficiency
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(2)
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EE1302 TRANSMISSION AND DISTRIBUTION ENGINEERING
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6.i) Describe with the neat sketch, the
construction of a 3 core belted type cable. (8)
ii)
A conductor of 1cm diameter passes centrally through porcelain cylinder of
internal diameter 2 cms and external diameter 7cms. The cylinder is surrounded
by a tightly fitting metal sheath. The permittivity of porcelain is 5 and the
peak voltage gradient in air must not exceed 34kV/cm. Determine the maximum
safe working voltage. (8)
7.i)
What are the various properties of insulators? Also briefly explain about
suspension type insulators. (8)
ii)
Calculate the most economical diameter of a single core cable to be used on
132kV, 3 phase system. Find also the overall diameter of the insulation, if the
peak
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permissible stress
does not exceed 60kV/cm. Also derive the formula used.
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(8)
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8. i) Briefly
explain about various types of cables used in underground system.
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(8)
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ii)
A
string of 4 insulator units has a self capacitance equal to 4 times the pin to
earth capacitance. Calculate,
a)
Voltage
distribution as a % of total voltage
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b) String efficiency
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(8)
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9. i) Give any six
properties of a good insulator.
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(4)
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ii) With a neat diagram, explain the
strain and stay insulators.
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(4)
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iii)
A cable is graded with three dielectrics of permittivities 4,3 and 2. The
maximum permissible potential gradient for all dielectrics is same and equal to
30 kV/cm.
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The core diameter
is 1.5cm and sheath diameter is 5.5cm.
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(8)
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10.i) Explain the
constructional features of one LT and HT cable
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(8)
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ii) Compare and contrast overhead
lines and underground cables.
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(8)
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UNIT- V
SUBSTATION GROUNDING
SYSTEM AND DISTRIBUTION SYSTEM
PART- A (2 MARKS)
2.
What
are the conditions of laying out a substation?
3.
What
are the classifications of substation according to service?
4.
What
are the types of transformer substations?
5. What
are the classifications of substations due to construction? 6.What are the
equipments used in a transformer substation?
7.What
are the different types of bus bar arrangements in substations?
9. What are the
materials mainly used in busbars?
10. What are the factors
to be considered for busbar design?
11. Which tests are
necessary on station busbars?
12. What is neutral
grounding or neutral earthing?
13. What is equipment
grounding?
14. What are the
advantages of neutral grounding?
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EE1302 TRANSMISSION AND DISTRIBUTION ENGINEERING
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15.
What
is earth resistance?
16. What are the devices
used for DC power at the substation by using converting machinery?
17.
Define
distribution substation.
18.
Define
service mains?
19.
What
are the types of nature of current in distribution system?
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PART-B
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1.
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With a neat
sketch explain double bus with double breaker and double bus with
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single breaker.
State their advantages and disadvantages.
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(16)
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2.Explain the
following:
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(i) Neutral grounding
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(16)
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(ii) Resistance
grounding.
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3.
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Explain about the various types of
substations
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(16)
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4.
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Write short notes on
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(4)
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I. Sub mains
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II.
Stepped and tapered mains
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(12)
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5.
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Explain the substation bus schemes.
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(16)
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6.
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Write short notes on
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(8)
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i. Busbar
arrangement in substation
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ii. Grounding grids
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(8)
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7. i) Explain the
design principles of substation grounding system.
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(8)
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ii) Explain the equipments in a
transformer substation.
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(8)
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