The document discusses types of underground power cables. It describes single-core and multi-core cables, their construction including conductor, insulation, sheathing, and armor. It discusses cable classification based on operating voltage and insulation material. Methods of cable laying and factors affecting reliability are also summarized. Cable testing methods include insulation resistance testing and capacitance testing to determine cable parameters.
Underground cables are used for power applications where it is impractical, difficult, or dangerous to use the overhead lines. They are widely used in densely populated urban areas, in factories, and even to supply power from the overhead posts to the consumer premises.
The underground cables have several advantages over the overhead lines; they have smaller voltage drops, low chances of developing faults and have low maintenance costs. However, they are more expensive to manufacture, and their cost may vary depending on the construction as well as the voltage rating.
The underground cables are classified in two ways; by the voltage capacity, or by the construction.
By Voltage
LT cables: Low-tension cables with a maximum capacity of 1000 V
HT Cables: High-tension cables with a maximum of 11KV
ST cables: Super-tension cables with a rating of between 22 KV and 33 KV
EHT cables: Extra high-tension cables with a rating of between 33 KV and 66 KV
Extra super voltage cables: with maximum voltage ratings beyond 132 KV
By Construction
Belted cables: Maximum voltage of 11KVA
Screened cables: Maximum voltage of 66 KVA
Pressure cables: the Maximum voltage of more than 66KVA
Since the loads having the trends towards growing density. This requires the better appearance, rugged construction, greater service reliability and increased safety. An underground cable essentially consists of one or more conductors covered with suitable insulation and surrounded by a protecting cover. The interference from external disturbances like storms, lightening, ice, trees etc. should be reduced to achieve trouble free service. The cables may be buried directly in the ground, or may be installed in ducts buried in the ground.
Townsend ’s theory
Introduction
Ionization by collision
Townsend’s current growth equation
Current Growth in the Presence of Secondary Processes
Townsend’s secondary ionization coefficient
Townsend’s Criterion for Breakdown
Breakdown in Electronegative Gases
it is a ppt on the subject of engineering study. ELECTRICAL POWER SYSTEM. cables type witch is use for the high voltage transmission. in this ppt only under ground cables types are present.
Construction of cables
Insulation resistance of a single core cable
Capacitance of a single core cable
Dielectric stress in a single core cable
Grading of Cables-Capacitance grading and Inter sheath grading
Capacitance of 3-Core Cables
Problems
Underground cables are used for power applications where it is impractical, difficult, or dangerous to use the overhead lines. They are widely used in densely populated urban areas, in factories, and even to supply power from the overhead posts to the consumer premises.
The underground cables have several advantages over the overhead lines; they have smaller voltage drops, low chances of developing faults and have low maintenance costs. However, they are more expensive to manufacture, and their cost may vary depending on the construction as well as the voltage rating.
The underground cables are classified in two ways; by the voltage capacity, or by the construction.
By Voltage
LT cables: Low-tension cables with a maximum capacity of 1000 V
HT Cables: High-tension cables with a maximum of 11KV
ST cables: Super-tension cables with a rating of between 22 KV and 33 KV
EHT cables: Extra high-tension cables with a rating of between 33 KV and 66 KV
Extra super voltage cables: with maximum voltage ratings beyond 132 KV
By Construction
Belted cables: Maximum voltage of 11KVA
Screened cables: Maximum voltage of 66 KVA
Pressure cables: the Maximum voltage of more than 66KVA
Since the loads having the trends towards growing density. This requires the better appearance, rugged construction, greater service reliability and increased safety. An underground cable essentially consists of one or more conductors covered with suitable insulation and surrounded by a protecting cover. The interference from external disturbances like storms, lightening, ice, trees etc. should be reduced to achieve trouble free service. The cables may be buried directly in the ground, or may be installed in ducts buried in the ground.
Townsend ’s theory
Introduction
Ionization by collision
Townsend’s current growth equation
Current Growth in the Presence of Secondary Processes
Townsend’s secondary ionization coefficient
Townsend’s Criterion for Breakdown
Breakdown in Electronegative Gases
it is a ppt on the subject of engineering study. ELECTRICAL POWER SYSTEM. cables type witch is use for the high voltage transmission. in this ppt only under ground cables types are present.
Construction of cables
Insulation resistance of a single core cable
Capacitance of a single core cable
Dielectric stress in a single core cable
Grading of Cables-Capacitance grading and Inter sheath grading
Capacitance of 3-Core Cables
Problems
A Presentation based on Underground Cables Used In the Transmission And Distribution System.It is a topic covered in the syllabus of B.E. in Electrical Engineering in 5th semester Subject named "Electrical Power System" For more detail you can check the book "Electrical Power System" by Author V.K.Mehta and S.Chand Publication.
Modern underground power cables are sophisticated assemblies of insulators, conductors and protective materials. Within these components are sensors, which enable cable operators to monitor conditions along the cable in real time.
The condition of the cable insulation is usually monitored through the following two main methods:
Loss tangent measurements
Partial discharge (PD) measurements
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NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
An Approach to Detecting Writing Styles Based on Clustering Techniquesambekarshweta25
An Approach to Detecting Writing Styles Based on Clustering Techniques
Authors:
-Devkinandan Jagtap
-Shweta Ambekar
-Harshit Singh
-Nakul Sharma (Assistant Professor)
Institution:
VIIT Pune, India
Abstract:
This paper proposes a system to differentiate between human-generated and AI-generated texts using stylometric analysis. The system analyzes text files and classifies writing styles by employing various clustering algorithms, such as k-means, k-means++, hierarchical, and DBSCAN. The effectiveness of these algorithms is measured using silhouette scores. The system successfully identifies distinct writing styles within documents, demonstrating its potential for plagiarism detection.
Introduction:
Stylometry, the study of linguistic and structural features in texts, is used for tasks like plagiarism detection, genre separation, and author verification. This paper leverages stylometric analysis to identify different writing styles and improve plagiarism detection methods.
Methodology:
The system includes data collection, preprocessing, feature extraction, dimensional reduction, machine learning models for clustering, and performance comparison using silhouette scores. Feature extraction focuses on lexical features, vocabulary richness, and readability scores. The study uses a small dataset of texts from various authors and employs algorithms like k-means, k-means++, hierarchical clustering, and DBSCAN for clustering.
Results:
Experiments show that the system effectively identifies writing styles, with silhouette scores indicating reasonable to strong clustering when k=2. As the number of clusters increases, the silhouette scores decrease, indicating a drop in accuracy. K-means and k-means++ perform similarly, while hierarchical clustering is less optimized.
Conclusion and Future Work:
The system works well for distinguishing writing styles with two clusters but becomes less accurate as the number of clusters increases. Future research could focus on adding more parameters and optimizing the methodology to improve accuracy with higher cluster values. This system can enhance existing plagiarism detection tools, especially in academic settings.
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
3. Affected by ice, snow,
rain, wind, dust,smoke
or fog.
Affected by Ice storms,
Tornadoes,Hurricanes.
High maintenance
costs.
Value of land and
buildings gets affected.
Greater faults, bumps
on power system.
Higher voltage drops.
Greater security of supply,
particularly in bad weather.
Lower transmission losses,
Virtually no maintenance.
No noise or air pollution
(due to “corona
discharge”).
No electric field and lower
magnetic field outside the
right of way.
Landscape can be
reinstated.
Long planning delays can
by avoided.
MAIN
5. Conductor : Class 2 stranded plain copper conductor to BS
Conductor Screen : Semi-conducting material
Insulation : XLPE (Cross-Linked Polyethylene)
Insulation Screen : Semi-conducting material
Metallic Screen : Individual and overall copper tape screen to
BS6622
Filler : PETP (Polyethylene Terephthalate) fibres
Separator : Binding tape
Bedding : PVC (Polyvinyl Chloride) Type TM1 to BS7655
Armouring :Galvanised steel wire.
Single Core : AWA (Aluminium Wire Armoured)
Multi-Core: SWA (Steel Wire Armoured)
Sheath : PVC (Polyvinyl Chloride) Type TM1 to BS7655
Voltage Rating : 19000/33000V
Temperature Rating : 0°C to +90°C
6. TheVarious Parts Are:-
Cores or Conductors: The conductors are made of tinned copper or aluminium
and are usually stranded in order to provided flexibility of the cables.
Insulation: Thickness of insulation depends on the voltage to be withstood by
the cable.
Metallic sheath: It protects the cable from moisture, gases or other damaging
liquids in soil & atmosphere, a metallic sheath of lead or aluminium is provided.
Bedding: It protects the metallic sheath against corrosion and from mechanical
injuries due to armouring.
Armouring : It protects the cable from mechanical injury while laying.
Serving : It protects armouring from atmospheric conditions, a layer of fibrous
material similar to bedding is provided over the armouring.
MAIN
7. CHARACTERISTICS
• High insulation resistance
• High dielectric strength
• Non Hygroscopic
• High mechanical strength
• Non inflammable
• Non affected by acids and
alkalies
• Low cost
Types of insulating
materials
• Rubber
• Vulcanised India rubber
• Impregnated paper
• Varnished Cambric
• Polyvinyl chloride (PVC)
• Crosslinked polyethylene
(XLPE)
MAIN
8. 1. Low voltage (L.T.) cable (operating
Voltage up to 1 KV
3.Super tension (S.T)
Cable (operating voltage
Up to 33 KV.)
5.Extra super voltage
Cable (operating voltage
up to 132 KV.
4. Extra super tension
(E.H.T.) cable (operating
Voltage up to 66KV.
2. High voltage (H.T)
Cable (operating voltage
Up to 11 KV)
On the basis of insulating material
On the basis of Operating Voltage.
9. Belted cables -> upto 11 kV
-The cores are generally stranded and may be of non-
circular shape to make better use of available space.
-Suitable for low and medium voltages as electrostatic
stresses developed are mostly radial.
-At high voltages-tangential stresses set up leakage
current-that cause
heating-breakdown
of insulation.
10. Screened Cables ->from 22 to 66 kV
Each conductor insulated with
impregnated paper, covered
with a metallic screen of
aluminium foil.
Instead of paper belt, the three
cores are wrapped with a
conducting belt(copper woven
fabric tape) then lead sheath at
earth potential , due to which
electrical stresses are radial in
nature keeping the dielectric
losses to minimum.
The metallic screen avoids the
formation of voids & increase
heat dissipation.
11. Screened Cables ->from 22 to 66 kV
Each core is insulated with
impregnated paper and
each one is then covered
by separate lead sheath.
Due to individual lead
sheath, core to core fault
possibility gets minimised.
Due to absence of overall
lead sheath, bending of
cable is easy.
Thinner-require greater
care.
12. Advantages:
1. Formation of voids and
ionisation are avoided
2. Allowable temperature
range and dielectric
strength are increased
3. If there is leakage, the
defect in lead sheath is
at once indicated and
the possibility of earth
faults is decreased.
Disadvantages:
1. High initial cost
2. Complicated system of
laying
OIL DUCT
Oil Pressure is 0.2
Kg/cm2
They can range up to
345KV
Pressure cables
13. Pressure cables
-The cable is laid in gas-tight steel
pipe which is filled with
dry nitrogen gas at 12 to 15 atmospheres.
-The thickness of lead sheath is 75% of that
of solid type cable.
Advantages:
1. They carry more load current.
2. They operate at higher voltages than a
normal cable.
3. Maintenance cost is small.
4. Nitrogen gas helps in quenching any
flame.
5. No reservoir or tanks required.
6. The power factor is improved.
Disadvantage:
1. Overall cost is very high.
MAIN
14. The reliability of underground cable network
depends upon the proper laying.
A trench of about 1.5 metres deep and 45 cm wide
is dug. A cable is laid over a sand bed (10 cm) and is
covered with concrete material and bricks in order
to protect it from mechanical injury.
Gives the best dissipating conditions beneath the
earth. It is clean and safe method.
Localisation of fault is difficult. It can be costlier in
congested areas where excavation is inconvenient.
The maintenance cost is high.
15. -In this conduit or duct of concrete Is laid in ground with main holes at
suitable positions along the cable route.
-The cables are then pulled into positions from main holes.
This method is suitable for congested areas where excavation is expensive
and inconvenient.
-Less chance of fault due to strong
mechanical protection.
-Initial cost is very high.
-Heat dissipation condition are
not good.
16. In this system the cable is laid in open pipes or troughs
dug out in earth along the cable route.
The troughing is of cast iron or treated wood.
Troughing is filled with a bituminous after cable is laid.
-Provides good mechanical strength.
-Has poor heat dissipation conditions.
-Require skilled labour and favorable weather conditions.
-Very much expensive.
MAIN
17. In these cables, the leakage current flows
radially from centre towards the surface.
The resistance offered by cable to path of
the leakage current is called an insulation
resistance. So to calculate the insulation
resistance consider an elementary section
of the cylindrical cable of radius x and the
thickness dx.
Let d =Diameter of the core / conductor
r = Radius of the core
D= Diameter of the sheath
R= = Radius of cable with sheath
As the leakage current flows radially outwards, the length along which the
current flows in an elementary ring is dx. While the crossectional area
perpendicular to the flow of current depends on the length of cable=(2πx)* l
18. Hence the resistance of this elementary cylinder shell is :
The total insulation resistance of the cable can be obtained by integrating the
resistance of an elementary ring from inner radius up to outer radius i.e. r to R.
The value of Ri is always very high. The expression shows that the insulation
resistance is inversely proportional to its length. So as the cable length increases,
the insulation resistance decreases.
19. A single core cable is equivalent to two long co-axial cylinders.The inner
cylinder is the conductor itself while the outer cylinder is the lead sheath.
The lead sheath is always at earth potential.
Let d = Conductor diameter, D =Total diameter with sheath
Let Q = Charge per meter length of conductor in coulombs
ε = Permittivity of material between core and sheath
Now ε = εo εr
Now, electric flux density at a
distance x meters from the axis,
D= C/m2
The value of electric intensity,
E = = V/m
20. dV = E. dx Volts
V = = = = V/m
Therefore the capacitance of the cable is given by C= F/m
Thus substituting the values of known constants we get C=
21. The electrical stress in insulation is the electric
field intensity acting at any point P in
insulation.
The stress is maximum at the surface of the
conductor i.e. when x = r.
22. Similar the minimum stress will be at the
length i.e. x = R hence
The ratio of maximum and minimum stress is,
NEXT
23. Now the value of ∂gmax/∂d must be zero
to get minimum gmax.Therefore..
The value of minimum gmax is,
=>
When the voltageV and sheath diameter D are fixed, the only parameter to be
selected is the core diameter d. So d should be selected for which value is minimum.
The value of will be minimum when ∂gmax/∂d = 0
Most Economical Conductor Size
MAIN
24. The unequal distribution of stress has two effects,
1. Greater insulation thickness is required, which increases the cost and size.
2. It may lead to the breakdown of insulation.
Hence the grading of cables is done.
There are two methods of grading the cables:
Capacitance Grading
The process of achieving uniformity in the dielectric
stress by using layers of different dielectrics.
Suppose there are three dielectrics of outer
diameter d1 d2 and D and relative
permeability ἐ1 > ἐ2 > ἐ3 and they are worked
at the same maximum stress.Then-
ἐ1d = ἐ2d1 = ἐ3d2
26. Intersheath Grading
In this method of grading, in between the
core and the lead sheath number of metallic
sheaths are placed which are called
intersheaths.
Consider a cable with core diameter d and
overall diameter with lead sheath as D. Let
two intersheaths are used having diameter
d1 and d2 which are kept at the potentials
V1 andV2respectively.
Maximum stress between
core and the first intersheath
is:
Similarly,
27. Since the dielectric is homogeneous, the maximum stress in each layer
is the same i.e,
g1max = g2max = g3max = gmax (say)
Disadvantages
-Complications in fixing the sheath potentials.
-Danger of damage to intersheaths while transporting
and installation.
-Losses due to charging current.
MAIN
28. In underground cables capacitance becomes much more important than
what it is in over head system because:
Conductors are nearer to each other and to the earthed sheath.
They are separated by a dielectric of permittivity much greater
than that of air.
The capacitances are shown in the Fig.
Cc Cc
Cc
Cs
Cs
Cs
29. The core to core capacitances are
denoted as Cc while core to sheath
capacitance are denoted as Cs.
The core to core capacitances Cc are
in delta and can be represented in the
equivalent star as shown in the Fig.
The impedance between core 1 and the star point, Z1 can be obtained as,
30. O
CN = C1 + 3Cc
CN = C1 + 3Cc CN = C1 + 3Cc
C1 Cs
Cs
C1
Cs
C1
If star point is assumed to be at earth potential and if sheath is also earthed then
the capacitance of each conductor to neutral is,
31. IfVph is the phase voltage then charging current per phase is,
MAIN
32. The three cores are bunched together and the capacitance is measured between
the bunched cores and the sheath.
It eliminates capacitor Cc leaving Cs in parallel.Therefore:
C1=3Cs
Or Cs=C1/3
In this two cores are bunched with the sheath and the capacitance
is measured between them and the third core.
If C2 is measured capacitance, then
C2= 2Cc + Cs
Cs is found from first test.
C2 can be experimentally , hence Cc can be determined.
C1
C2
Sheath
Cores
33. If value of Cn=(Cs+3Cc) is desired, there’s another test.
The capacitance between the two cores or lines is measured with the third
core free or connected to the sheath.
This eliminates one of the capacitors Cs so that C3 is the measured
capacitance, then
C3 = Cc + Cc/2 + Cs/2
= (Cs + 3Cc)/2
=Cn /2 C3
34. Cables are generally laid directly in the ground or in the ducts , for this
reason there are little chances of faults in underground cables.
Open-circuit fault- Occurs when there is a break in the
conductor of a cable. It can be checked by a megger.
Short-circuit fault- Occurs when two conductors of a multi-core
cable come in electrical contact with each other.
Earth fault- Occurs when conductor of a cable comes in contact
with the earth.