The document discusses electrical insulators. It defines an insulator as a material that does not allow electric charges to flow through it easily. Insulators have high resistivity. Some common insulator materials are glass, paper, and Teflon. Insulators are used in electrical equipment to support conductors without allowing current to pass through. The document then discusses characteristics insulators should have such as mechanical strength, high dielectric strength, and resistance to impurities. It also discusses common insulator types like porcelain, glass, and polymer insulators as well as insulator components like pin, suspension, strain, and shackle insulators. Finally, it lists some common causes of insulator failure such as cracking, defective materials, por
This is a small ppt made by me to describe about the basics of Insulators in HV , EHV transmission lines.Students who want to go through the basics for clearing the fundamentals they can go through this ppt. Thank you.
This is a small ppt made by me to describe about the basics of Insulators in HV , EHV transmission lines.Students who want to go through the basics for clearing the fundamentals they can go through this ppt. Thank you.
Power Cables, Electrical Power & Industrial Cable, Electrical Wire, PVC Wire ...Ajjay Kumar Gupta
Power Cables, Electrical Power & Industrial Cable, Electrical Wire, PVC Wire and Cables Manufacturing Plant, Detailed Project Report, Profile, Business Plan, Industry Trends, Market Research, Survey, Manufacturing Process, Machinery, Raw Materials, Feasibility Study, Investment Opportunities, Cost and Revenue, Plant Economics, Production Schedule, Working Capital Requirement, Plant Layout, Process Flow Sheet, Cost of Project, Projected Balance Sheets, Profitability Ratios, Break Even Analysis
Electrical power cables used for transmission and distribution purposes consist of conductors stranded from plain high conductively annealed copper wires insulated with oil impregnated paper tapes. Underground construction is necessitated in the more density built up portions of cities by the heavy transformers and lines required and by the multiplication of service connections to buildings. The cable may include uninsulated conductors used for the circuit neutral or for ground (earth) connection.
See more
http://goo.gl/16DrCj
http://goo.gl/xjRO5z
http://goo.gl/4u2sr4
Contact us
Niir Project Consultancy Services
106-E, Kamla Nagar, New Delhi-110007, India.
Email: npcs.ei@gmail.com , info@entrepreneurindia.co
Tel: +91-11-23843955, 23845654, 23845886, 8800733955
Mobile: +91-9811043595
Website : www.entrepreneurindia.co , www.niir.org
Tags
PVC Cable Manufacturing Process, Manufacturing Process of Cables, Power Cables Manufacturing Process, Electric Cable Manufacturing, Wire Manufacturing Process, Manufacturing Process of Industrial Cables, Electric Cable Making Machine, Wire and Cable Construction, Power Cable Manufacture In India, Wire & Cable Projects, PVC Wires and Cables Manufacturing Plant, Power Cables Manufacture, Power Cable Manufacturing, Electrical Cable Manufacturing Process, Electrical Cable Manufacturing, Cable Production, Cable Manufacturing Process, Electric Cable Manufacturing In India, Electric Cables Manufacture, Manufacture of Electric Power Cables, Project Profile on Electric Power Cable, Industrial Cable Manufacture, Industrial Wire & Cable, Wire and Cable Manufacturing Industry, Wire & Cable Manufacturing, Cable Manufacturing Industry, Industrial Wire & Cable Manufacture, Industrial Cable Production, Production of Electrical Power & Industrial Cable, PVC Wire and Cable Manufacturing Machine, PVC Cable Machinery Plant, Manufacture of PVC Cable, PVC Wires & Cables Industry Projects, Report on PVC Cables, PVC Cables Processing, PVC Wire Manufacturing, Manufacture of PVC Wire, PVC Wire Machinery Plant, PVC Wire Plant, Industrial Wire Manufacturing, Electrical Wire Manufacturing, PVC Wire Production, Industrial Wire Production, Electrical Cable Production, Power Cable Production, Industrial Cable Production Project Ideas, Projects on Small Scale Industries, Small Scale Industries Projects Ideas, Industrial Cable Production Based Small Scale Industries Projects
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
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
In this section, we will discuss
1. Breakdown of Insulators
2. Uses
3. Insulation in electrical apparatus
3.1 Class I and Class II insulation
3.2power transmission insulators
4.1 Material
4.2 Design
4.3 Types of insulators
4.4 Sheath insulator
4.5 Suspension insulators
Power Cables, Electrical Power & Industrial Cable, Electrical Wire, PVC Wire ...Ajjay Kumar Gupta
Power Cables, Electrical Power & Industrial Cable, Electrical Wire, PVC Wire and Cables Manufacturing Plant, Detailed Project Report, Profile, Business Plan, Industry Trends, Market Research, Survey, Manufacturing Process, Machinery, Raw Materials, Feasibility Study, Investment Opportunities, Cost and Revenue, Plant Economics, Production Schedule, Working Capital Requirement, Plant Layout, Process Flow Sheet, Cost of Project, Projected Balance Sheets, Profitability Ratios, Break Even Analysis
Electrical power cables used for transmission and distribution purposes consist of conductors stranded from plain high conductively annealed copper wires insulated with oil impregnated paper tapes. Underground construction is necessitated in the more density built up portions of cities by the heavy transformers and lines required and by the multiplication of service connections to buildings. The cable may include uninsulated conductors used for the circuit neutral or for ground (earth) connection.
See more
http://goo.gl/16DrCj
http://goo.gl/xjRO5z
http://goo.gl/4u2sr4
Contact us
Niir Project Consultancy Services
106-E, Kamla Nagar, New Delhi-110007, India.
Email: npcs.ei@gmail.com , info@entrepreneurindia.co
Tel: +91-11-23843955, 23845654, 23845886, 8800733955
Mobile: +91-9811043595
Website : www.entrepreneurindia.co , www.niir.org
Tags
PVC Cable Manufacturing Process, Manufacturing Process of Cables, Power Cables Manufacturing Process, Electric Cable Manufacturing, Wire Manufacturing Process, Manufacturing Process of Industrial Cables, Electric Cable Making Machine, Wire and Cable Construction, Power Cable Manufacture In India, Wire & Cable Projects, PVC Wires and Cables Manufacturing Plant, Power Cables Manufacture, Power Cable Manufacturing, Electrical Cable Manufacturing Process, Electrical Cable Manufacturing, Cable Production, Cable Manufacturing Process, Electric Cable Manufacturing In India, Electric Cables Manufacture, Manufacture of Electric Power Cables, Project Profile on Electric Power Cable, Industrial Cable Manufacture, Industrial Wire & Cable, Wire and Cable Manufacturing Industry, Wire & Cable Manufacturing, Cable Manufacturing Industry, Industrial Wire & Cable Manufacture, Industrial Cable Production, Production of Electrical Power & Industrial Cable, PVC Wire and Cable Manufacturing Machine, PVC Cable Machinery Plant, Manufacture of PVC Cable, PVC Wires & Cables Industry Projects, Report on PVC Cables, PVC Cables Processing, PVC Wire Manufacturing, Manufacture of PVC Wire, PVC Wire Machinery Plant, PVC Wire Plant, Industrial Wire Manufacturing, Electrical Wire Manufacturing, PVC Wire Production, Industrial Wire Production, Electrical Cable Production, Power Cable Production, Industrial Cable Production Project Ideas, Projects on Small Scale Industries, Small Scale Industries Projects Ideas, Industrial Cable Production Based Small Scale Industries Projects
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
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
In this section, we will discuss
1. Breakdown of Insulators
2. Uses
3. Insulation in electrical apparatus
3.1 Class I and Class II insulation
3.2power transmission insulators
4.1 Material
4.2 Design
4.3 Types of insulators
4.4 Sheath insulator
4.5 Suspension insulators
Study of Insulators- cotton insulator, Enamel, insulating oil, mica, paper insulator, Pin type insulator, Porcelain, Properties of insulators, rubber insulator, silk, Strain insulators, Suspension type Strain type Insulators, Varnish,
Manufacturing of Porcelain Insulators. Profitable Investment in Porcelain Electric Insulators Industry.
Porcelain in most typically used material for overhead insulator in present days. The porcelain is aluminum salt. The atomic number 13 salt is mixed with plastic porcelain clay, spar and quartz to get final laborious and glazed porcelain material. The surface of the insulator ought to be glazed enough in order that water shouldn't be derived on that. Porcelain conjointly ought to be free from porosity since porosity is the main reason for deterioration of its dielectric property. It should even be free from any impurity and bubble within the material which can have an effect on the insulator properties.
For More Details, Click Here:- https://bit.ly/3iz6geI
Contact us
Niir Project Consultancy Services
An ISO 9001:2015 Company
106-E, Kamla Nagar, Opp. Spark Mall,
New Delhi-110007, India.
Email: npcs.ei@gmail.com , info@entrepreneurindia.co
Tel: +91-11-23843955, 23845654, 23845886
Mobile: +91-9097075054, 8800733955
Website: www.entrepreneurindia.co , www.niir.org
Potential and Electric Field Characteristics of Broken Porcelain Insulator IJECEIAES
Overhead line insulators can be damaged for various reasons during their service life. Porcelain or glass insulators once damaged can affect the reliability of power system networks. This paper presents the study of voltage and electric characteristics along the surface of a broken porcelain insulator located in a string of 10 unit insulators. Three models of broken porcelain insulators were being proposed and the analysis results on voltage and electric characteristics were individually collected. The broken porcelain insulator with the most significant effect were then being investigated in the strings of 10 unit insulators. The finite element software of Quickfield was used to analyze the voltage and electric characteristics. Form the presented results, it is proven that the single porcelain insulators with broken shed at the nearest to the electrode terminal gave the most significant effect of voltage and electric field distribution pattern along the creepage distance. However, when this type of broken insulator was included in a string of 10 unit insulators, maximum average value of voltage achieved once the broken insulator was located at the HV terminal. Meanwhile, the highest electric field strength was recorded when the broken insulator was located in the middle of the string.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
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.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
2. What is an electric insulator
An electrical insulator is a material whose internal electric
charges do not flow freely, and therefore make it nearly
impossible to conduct an electric current under the influence of
an electric field. This contrasts with other
materials, semiconductors and conductors, which conduct
electric current more easily. The property that distinguishes an
insulator is its resistivity; insulators have higher resistivity than
semiconductors or conductors
3. • A perfect insulator does not exist, but some materials
such as glass, paper and Teflon, which have high
resistivity, are very good electrical insulators.
• Insulators are used in electrical equipment to support
and separate electrical conductors without allowing
current through themselves
• Insulators for overhead line provide insulation to power
conductors from ground.
4. Characteristics of solid insulator
It must be mechanically strong enough to carry tension and
weight of conductors.
It must have very high dielectric strength to withstand the
voltage stresses in High Voltage system.
It must possesses high Insulation Resistance to prevent leakage
current to the earth.
The insulating material must be free from unwanted
impurities..
5. Cont…
It should not be porous.
There must not be any entrance on the surface of electrical
insulator so that the moisture or gases can enter in it.
There physical as well as electrical properties must be less
effected by changing temperature
Withstand flashover phenomenon
6. Some terms
dielectric strength has the following meanings: Of an insulating material,
the maximum electric field that a pure materialcan withstand under ideal
conditions without breaking down (i.e., without experiencing failure of its
insulating properties).
Compressive strength is the maximum compressive stress that, under a
gradually applied load, a given solid material can sustain without fracture.
Compressive strength is calculated by dividing the maximum load by the
original cross-sectional area of a specimen in a compression test.
Tensile strength is a measurement of the force required to pull something
such as rope, wire, or a structural beam to the point where it breaks.
The tensile strength of a material is the maximum amount of tensile stress
that it can take before failure, for example breaking.
7. Insulators materials
Porcelain Insulator
Porcelain in most commonly used material for over head
insulator in present days. The porcelain is aluminium silicate.
The aluminium silicate is mixed with plastic kaolin, feldspar
and quartz to obtain final hard and glazed porcelain insulator
material. The surface of the insulator should be glazed enough
so that water should not be traced on it. Porcelain also should
be free from porosity since porosity is the main cause of
deterioration of its dielectric property. It must also be free from
any impurity and air bubble inside the material which may
affect the insulator properties.
8. Cont..
Properties of Porcelain Insulator
Property Value(Approximate)
Dielectric Strength 60 KV / cm
Compressive Strength 70,000 Kg / cm2
Tensile Strength 500 Kg / cm2
9.
10.
11. Glass Insulator
Now days glass insulator has become popular in
transmission and distribution system. Annealed tough
glass is used for insulating purpose. Glass insulator has
numbers of advantages over conventional porcelain
insulator.
12.
13.
14. Advantages of Glass Insulator
1. It has very high dielectric strength compared to porcelain.
2. Its resistivity is also very high.
3. It has low coefficient of thermal expansion.
4. It has higher tensile strength compared to porcelain
insulator.
5. As it is transparent in nature the is not heated up in sunlight
as porcelain.
6. The impurities and air bubble can be easily detected inside
the glass insulator body because of its transparency.
7. Glass has very long service life as because mechanical and
electrical properties of glass do not be affected by ageing.
8. After all, glass is cheaper than porcelain.
15. Disadvantages of Glass Insulator
1. Moisture can easily condensed on glass surface and
hence air dust will be deposited on the wed glass
surface which will provide path to the leakage current
of the system.
2. For higher voltage glass can not be cast in irregular
shapes since due to irregular cooling internal cooling
internal strains are caused.
16. Properties of Glass Insulator
Property Value(Approximate)
Property Value(Approximate)
Dielectric Strength
140 KV / cm
Compressive Strength 10,000 Kg / cm2
Tensile Strength 35,000 Kg / cm2
17. Polymer Insulator
In a polymer insulator has two parts, one is glass
fiber reinforced epoxy resin rod shaped core and other
is silicone rubber or EPDM (Ethylene Propylene
Diene Monomer) made weather sheds. Rod shaped
core is covered by weather sheds. Weather sheds
protect the insulator core from outside environment.
As it is made of two parts, core and weather sheds,
polymer insulator is also called composite
insulator. The rod shaped core is fixed with Hop dip
galvanized cast steel made end fittings in both sides.
18.
19.
20. Advantages of Polymer Insulator
1. It is very light weight compared to porcelain and glass
insulator.
2. As the composite insulator is flexible the chance of
breakage becomes minimum.
3. Because of lighter in weight and smaller in size, this
insulator has lower installation cost.
4. It has higher tensile strength compared to porcelain
insulator.
5. Its performance is better particularly in polluted areas.
6. Due to lighter weight polymer insulator imposes less load
to the supporting structure.
7. Less cleaning is required due to hydrophobic nature of the
insulator.
21. Disadvantages of Polymer Insulator
1. Moisture may enter in the core if there is any
unwanted gap between core and weather sheds. This
may cause electrical failure of the insulator.
2. Over crimping in end fittings may result to cracks
in the core which leads to mechanical failure of
polymer insulator.
22. There are several types of insulators but the
most commonly used are :
1) Pin Insulator
2) Suspension Insulator
3) Strain Insulator and
4) Shackle insulator.
23.
24. A pin insulator consists of a nonconducting material such as
porcelain, glass, plastic, polymer, or wood.
As the name suggests, the pin type insulator is secured to the
cross-arm on the pole.
There is a groove on the upper end of the insulator for
housing the conductor.
The conductor passes through this groove and is bound by
the annealed wire of the same material as the conductor.
Pin type insulators are used for transmission and distribution
of electric power at voltages upto 33 kV.
Beyond operating voltage of 33 kV, the pin type insulators
become too bulky and hence uneconomical
27. For high voltages (>33 kV), it is a usual practice to use
suspension type insulators consist of a number of porcelain
discs connected in series by metal links in the form of a
string.
The conductor is suspended at the bottom end of this
string while the other end of the string is secured to the
cross-arm of the tower.
Each unit or disc is designed for low voltage, say 11 kV.
The number of discs in series would obviously depend
upon the working voltage.
For instance, if the working voltage is 66 kV, then six discs
in series will be provided on the string.
28.
29.
30. When there is a dead end of the line or there is corner or
sharp curve, the line is subjected to greater tension.
In order to relieve the line of excessive tension, strain
insulators are used.
For low voltage lines (< 11 kV), shackle insulators are used as
strain insulators.
However, for high voltage transmission lines, strain insulator
consists of an assembly of suspension insulators as shown in
Figure.
The discs of strain insulators are used in the vertical plane.
When the tension in lines is exceedingly high, at long river
spans, two or more strings are used in parallel.
31.
32. Efficiency of string
efficiency=Voltage across the string
(n ×Voltage across disc nearest to conductor)
Where n = number of discs in the strin
34. In early days, the shackle insulators were used as
strain insulators.
But now a days, they are frequently used for low
voltage distribution lines.
Such insulators can be used either in a horizontal
position or in a vertical position.
They can be directly fixed to the pole with a bolt or
to the cross arm.
36. Causes of Insulator Failure
There are different causes due to which failure of
insulation in electrical power system may occur
1- Cracking of Insulator
The porcelain insulator mainly consists of three different
materials. The main porcelain body, steel fitting arrangement
and cement to fix the steel part with porcelain. Due to changing
climate conditions, these different materials in the insulator
expand and contract in different rate. These unequal expansion
and contraction of porcelain, steel and cement are the chief
cause of cracking of insulator.
2- Defective Insulation Material
If the insulation material used for insulator is defective
anywhere, the insulator may have a high chance of being
puncher from that place.
37. .
2- Porosity in The Insulation Materials
If the porcelain insulator is manufactured at low
temperatures, it will make it porous, and due to this reason
it will absorb moisture from air thus its insulation will
decrease and leakage current will start to flow through the
insulator which will lead to insulator failure.
3-Improper Glazing on Insulator Surface
If the surface of porcelain insulator is not properly glazed,
moisture can stick over it. This moisture along with
deposited dust on the insulator surface, produces a
conducting path. As a result the flash over distance of the
insulator is reduced. As the flash over distance is reduced,
the chance of failure of insulator due to flash over
becomes more.
38. .
4- Flash Over Across Insulator
If flash over occurs, the insulator may be over heated
which may ultimately results into shuttering of it.
5- Mechanical Stresses on Insulator
If an insulator has any weak portion due to manufacturing
defect, it may break from that weak portion when
mechanical stress is applied on it by its conductor. These
are the main causes of insulator failure. Now we will
discuss the different insulator test procedures to ensure
minimum chance of failure of insulation.
39. Insulator Testing
the electrical insulator must undergo the following tests
1. Flashover tests of insulator,
2. Performance tests and
3. Routine tests
40. Flashover Test
There are mainly 4 types of flashover test performed on an insulator
Power Frequency Dry Flashover Test of Insulator
1. First the insulator to be tested is mounted in the manner in which it
would be used practically.
2. Then terminals of variable power frequency voltage source are
connected to the both electrodes of the insulator.
3. Now the power frequency voltage is applied and gradually
increased up to the specified value. This specified value is below the
minimum flashover voltage.
4. This voltage is maintained for one minute and observe that there
should not be any flash-over or puncher occurred.
The insulator must be capable of sustaining the specified minimum
voltage for one minute without flash over.
41. Cont..
Power Frequency Wet Flashover Test or Rain Test of Insulator
1. In this test also the insulator to be tested is mounted in the manner
in which it would be used practically.
2. Then terminals of variable power frequency voltage source are
connected to the both electrodes of the insulator.
3. After that the insulator is sprayed with water at an angle of 45o in
such a manner that its precipitation should not be more 5.08 mm per
minute. The resistance of the water used for spraying must be
between 9 kΩ 10 11 kΩ per cm3 at normal atmospheric pressure and
temperature. In this way we create artificial raining condition.
4. Now the power frequency voltage is applied and gradually
increased up to the specified value.
5. This voltage is maintained for either one minute or 30 second as
specified and observe that there should not be any flash-over or
puncher occurred. The insulator must be capable of sustaining the
specified minimum power frequency voltage for specified period
without flash over in the said wet condition.
42. Cont…
Power Frequency Flashover Voltage test of Insulator
1. The insulator is kept in similar manner of previous test.
2. In this test the applied voltage is gradually increased in similar to
that of previous tests.
3. But in that case the voltage when the surroundings air breaks down,
is noted.
43. Cont..
Impulse Frequency Flashover Voltage Test of Insulator
The overhead outdoor insulator must be capable of sustaining high
voltage surges caused by lightning etc. So this must be tested against
the high voltage surges.
1. The insulator is kept in similar manner of previous test.
2. Then several hundred thousands Hz very high impulse voltage
generator is connected to the insulator.
3. Such a voltage is applied to the insulator and the spark over voltage
is noted.
The ratio of this noted voltage to the voltage reading collected from
power frequency flashover voltage test is known as impulse ratio of
insulator.
This ratio should be approximately 1.4 for pin type insulator and 1.3
for suspension type insulators.
44. Performance Test of Insulator
Now we will discuss performance test of insulator one by one-
Temperature Cycle Test of Insulator
1. The insulator is first heated in water at 70oC for one hour.
2. Then this insulator immediately cooled in water at 7oC for another
one hour.
3. This cycle is repeated for three times.
4. After completion of these three temperature cycles, the insulator is
dried and the glazing of insulator is thoroughly observed.
After this test there should not be any damaged or deterioration in the
glaze of the insulator surface.
Puncture Voltage Test of Insulator
1. The insulator is first suspended in an insulating oil.
2. Then voltage of 1.3 times of flash over voltage, is applied to the
insulator.
A good insulator should not puncture under this condition.
45. Cont
Porosity Test of Insulator
1. The insulator is first broken into pieces.
2. Then These broken pieces of insulator are immersed in a 0.5 %
alcohol solution of fuchsine dye under pressure of about 140.7 kg ⁄ cm2
for 24 hours.
3. After that the sample are removed and examine.
The presence of a slight porosity in the material is indicated by a deep
penetration of the dye into it.
Mechanical Strength Test of Insulator
1. The insulator is applied by 2½ times the maximum working strength
for about one minute.
The insulator must be capable of sustaining this much mechanical
stress for one minute without any damage in it.
46. Routine Test of Insulator
Each of the insulator must undergo the following routine test before
they are recommended for using at site.
Proof Load Test of Insulator
In proof load test of insulator, a load of 20% in excess of specified
maximum working load is applied for about one minute to each of the
insulator.
Corrosion Test of Insulator
In corrosion test of insulator,
1. The insulator with its galvanized or steel fittings is suspended into a
copper sulfate solution for one minute. 2. Then the insulator is
removed from the solution and wiped, cleaned. 3. Again it is
suspended into the copper sulfate solution for one minute. 4.The
process is repeated for four times.
47. Arcing horns
"Arcing horns" are projecting conductors used to protect
insulators on high voltage electric power transmission systems
from damage during flashover. Overvoltages on transmission
lines, due to atmospheric electricity, lightning strikes, or
electrical faults, can cause arcs across insulators that can
damage them