Underground cables are buried below ground to distribute electrical power or telecommunications as an alternative to overhead cables. They have several advantages over overhead cables including better safety, reliability of supply, and aesthetics as they are not exposed to weather damage and outages cannot occur. Underground cables have a more complex construction than overhead lines, involving one or more insulated conductors, insulation layers, metallic shielding, armor protection and serving. They are classified by voltage level and configuration. Higher voltage cables require additional features like pressurization or gas insulation to maintain performance. While having advantages, underground cables also have higher installation costs.
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
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.
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
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
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.
this ppt is base on construction of under ground cable. in this ppt i gave information the all type of insulation and its specification. and is advantages.
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.
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
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.
this ppt is base on construction of under ground cable. in this ppt i gave information the all type of insulation and its specification. and is advantages.
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
Parts of a cable
Properties of cable insulators
Properties of conductors
Types of cables
Underground cables
Methods of laying underground cables
Types of cable faults
Comparison between overhead and underground cables
How cables in underground wiring are different than overhead?We-Bore-It
Normally underground power cable contain one or more conductor which is covered with insulation. Most of underground cables are used for high electric power distribution purposes under urban areas. There are different types of cables mostly constructed to handle a certain range of voltages. Each of the cable type has its own pros & cons. The underground cables have several merits over the overhead lines; they have smaller voltage drops, low chances of developing faults and have low maintenance costs. We Bore It, a leading directional & boring service provider always prefer underground wiring whenever they get request for installing wires in illinois or other regions.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
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.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
2. z
Underground Cables
A cable that is buried below the ground.
They distribute electrical power or telecommunications.
Such cables are an alternative to overhead cables.
3. z
Introduction
Increasingly being adopted, although it is costly system of distribution as
compared to overhead system
It ensures the continuity of supply apart from the following advantages:
It ensures non-interrupted continuity of supply
Its maintenance is less
It has a long life
Its appearance is good
It eliminates hazards of electrocution due to breakage of over head conductors.
4. z
Advantages
Better general appearance
Less li able to damage
through storms or lighting
Low maintenance cost
Less chances of faults
Small voltage drop
Disadvantages
Greater installation cost and
introduce
6. z
Construction of Cables
Core or Conductor: A cable may have one or more than one
core depending upon the type of service for which it is intended.
The conductor could be of aluminum or copper and is stranded
in order to provide flexibility to the cable.
Insulation: The core is provided with suitable thickness of
insulation, depending upon the voltage to be withstood by the
cable. The commonly used material for insulation are
impregnated paper, varnished cambric or rubber mineral
compound.
7. z
Construction of Cables
Metallic Sheath: A metallic sheath of lead or aluminum is
provided over the insulation to protect the cable from moisture,
gases or others damaging liquids
Bedding: is provided to protect the metallic sheath from corrosion
and from mechanical damage due to armoring. It is a fibrous
material like jute or hessian tape. 7Professional Associates
Limited.
8. z
Construction of Cables
Armouring: Its purpose is to protect the cable from mechanical
injury while laying it or during the course of handling. It consists of
one or two layers of galvanized steel wire or steel tape.
Serving: To protect armouring from atmospheric conditions, a
layer of fibrous material is provided.
9. z
Properties of Insulating Material
High resistivity
High dielectric strength
Low thermal co-efficient
Low water absorption
Low permittivity
Non – inflammable
Chemical stability
High mechanical strength.
High viscosity at
impregnation temperature.
Capability to with stand high
rupturing voltage.
High tensile strength and
plasticity.
10. z
Classification Of Cables
Low tension (L.T) ----- up to 1000V
High tension (H.T) ----- up to 11, 000V
Super tension (S.T) ---- from 22KV to 33KV
Extra high tension (E.H.T) cables --- from 33KV to 66KV
Extra super voltage cables ------beyond 132KV
12. z
Single-core Cables
It consists of one circular core of tinned stranded copper or alo, insulated
by layers of impregnated paper.
lead sheath….. prevents the entry of moisture
Serving……to protect the lead sheath from corrosion
13. z
Cables for 3-phase Services
For voltage up to 66KV 3 core cable is preferred.
Following types of cables are generally used for 3 phase services
Belted cables---upto 11KV
Screened cables---from 22KV to 66 KV
Pressure cables---beyond 66KV
15. z
Belted Cables
In these cables the conductors are wrapped with oil impregnated paper,
and then cores are assembled with filler material. The assembly is
enclosed by paper insulating belt.
These can be used for voltages up to 11KV or in some cases can be used
up to 22KV.
High voltages beyond 22KV, the tangential stresses becomes an important
consideration.
As the insulation resistance of paper is quite small along the layer,
therefore tangential stress set up, hence, leakage current along the layer
of the paper insulation.
This leakage current causes local heating, resulting breaking of insulation
at any moment
16. z
Screened Cables
These can be used up to
33kv but in certain cases
can be extended up to
66kv.
These are mainly of two
types
H-type
S.L type cables
18. z
3- Core Cables H-TYPE Cables
Each core is insulated by layer of impregnated paper
The insulation on each core is covered with a metallic screen which is
usually of perforated aluminum foil
The cores are laid in such a way that metallic screen make contact with
one another
Basic advantage of H-TYPE is that the perforation in the metallic screen
assists in the complete impregnation of the cable with the compound
and thus the possibility of air pockets or voids in the dielectric is
eliminated
The metallic screen increase the heat dissipation power of the cable.
20. z
3-Core (S.L Type) Cables
S.L - Type: (Separate Lead)
Each core insulation is
covered by its own lead
sheath
21. z
Separate Lead Type Cables
Advantages
Firstly the separate sheath
minimize the possibility of
core-to-core breakdown.
Secondly the, bending of
cables become easy due to
the elimination of over all
sheath.
Disadvantages
The disadvantage is that the
lead sheaths of S.L is much
thinner as compared to H-
Type cables, therefore for
greater care is required in
manufacturing
22. z
Limitations of solid type cables
Above cables are referred to as solid type cables because solid insulation
is used and no gas or oil circulates in the cable sheath.
The voltage limit for solid type cables is 66 kV due to the following reasons :
23. z Reasons
a) As a solid cable carries the load, its conductor temperature increases and the
cable compound (i.e., insulating compound over paper) expands. This action
stretches the lead sheath which may be damaged.
b) When the load on the cable decreases, the conductor cools and a partial
vacuum is formed within the cable sheath. If the pinholes are present in the
lead sheath, moist air may be drawn into the cable.
c) In practice, voids are always present in the insulation of a cable. Under
operating conditions, the voids are formed as a result of the differential
expansion and contraction of the sheath and impregnated compound.
The breakdown strength of voids is considerably less than that of the insulation. If the
void is small enough, the electrostatic stress across it may cause its breakdown
24. z
Pressure Cables
When the operating voltages are greater than 66 kV and up to 230 kV,
pressure cables are used. In such cables, voids are eliminated by
increasing the pressure of compound and for this reason they are called
pressure cables.
Two Types
1. Oil-filled cables
2. Gas Pressure Cables
25. z
3-Core Cables (Pressurized Cables)
In these cables, pressure is maintained above atmosphere
either by oil or by gas
Gas pressure cables are used up to 275KV.
Oil filled cables are used up to 500KV.
27. z
Oil Filled Cables
In such types of cables, channels or ducts are provided in
the cable for oil circulation. The oil under pressure (it is the same
oil used for impregnation) is kept constantly supplied to the channel
by means of external reservoirs placed at suitable distances (say 500
m) along the route of the cable.
Low viscosity oil is kept under pressure and fills the voids in oil
impregnated paper under all conditions of varying load
28. z
Advantages of Oil Filled Cables
Greater operating dielectric stresses
Greater working temperature and current carrying capacity
Better impregnation
Impregnation is possible after sheath
No void formation
Smaller size of cable due to reduced dielectric thickness
Defect can easily be detected by oil leakage
31. z
Gas Pressure Cables
In these cables an inert gas like nitrogen is used to exert
pressure on paper dielectric to prevent void formation.
These are also termed as Compression cables
They insulated cores similar to solid type
The cable is inserted in a pressure vessel which may be a rigid
steel pipe, commonly known as pipe line compression cable.
32. z
…..
The nitrogen gas is filled in vessel at nominal pressure of 1.38 *
10 exp 6 N/ square meter with a maximum pressure of 1.725 *
10 exp 6 N/ square meter.
34. z
Gas Insulated Cables (GIC)
In GIC cables high pressure sulphur hexaflouride (SF6), fills the
small spaces in oil impregnated paper insulation and
suppresses the ionization.
Most EHV and UHV lines insulated with sulphur hexaflouride
(SF6) gas are being used extensively for voltages above 132 KV
up to 1200 KV.
These cables are very popular for short lengths, river crossings
and high way crossings.
35. z
Advantages of GIC
Gas Insulated Cables have several advantages over oil filled
cables, Efficient heat transfer hence can carry more current.
Low dielectric loss and low capacitance
SF6 gas is non-toxic, chemically stable and non-inflamable.
Terminations of GIC cables are simpler and cheaper.
36. z
Comparison b/w Underground and overhead
S.No. Particular Overhead system Underground system
1.
2.
3.
4.
5.
6.
7.
8.
Public safety
Initial cost
Faults
Appearance
Flexibility
Location of fault
Repair
Working voltage
It is less safe.
It is less expensive.
Faults occur frequently .
It gives shabby look.
It is more safe.
It is more expensive.
Very rare chances of faults.
Its appearance is good as wires are
not v1sible.
It is more flexible as new It 1s not flexible, as new
conductors can be laid along the conductors arc to be laid in new
existing conductors. channels.
Fault point can be easily located. Fault point cannot be easily
located.
Can be easily repaired. Cannot be easily repaired.
It can work upto 400 kV. It can work only upto 66 kV due
to insulation "difficulty.
37. z
9.
10.
11.
12.
13.
14.
15.
Lightning thunder
Supply interruption
Frequency of accidents
Interference with
communication system
Insulation cost
Erection cost
Uses
More chances of being subjected Very little chances of being to
lightning . subjected to lightning .
More chances of supply Very little chances of supply
interrruption. interruption.
More chances of accidents. Little chances of accidents.
It interferes with communication No interference with communi-
systems. cation system.
Less. The overhead conductor More insulation cost. Under are
bare. Supported on steel ground cables are provided with towers,
insulated from the various wrappings of high grade towers through
insulators. tape etc. Lead sheath is also
provided.
Much less comparatively Erection cost of high voltage
cable is quite high .
This is used for long distance The large charging current on
transmission high voltage limits the use of
long distance transmission .
An underground cable is a cable that is buried below the ground. They distribute electrical power or telecommunications. Such cables are an alternative to overhead cables, which are several meters above the ground. Overhead cables are often replaced withunderground cables