SF6 and vacuum circuit breakers are described. SF6 breakers use sulfur hexafluoride gas to rapidly absorb electrons in an electric arc, restoring insulation. Vacuum breakers extinguish arcs quickly due to the fast recovery of dielectric strength in a vacuum. Both breaker types have advantages like compact size, reliability, and lack of maintenance requirements, making them suitable for outdoor applications. Circuit breaker ratings include breaking capacity, making capacity, and short-time capacity to safely interrupt faults.
Unit I: Introduction to Protection System:
Introduction to protection system and its elements, functions of protective relaying, protective zones, primary and backup protection, desirable qualities of protective relaying, basic terminology.
Relays:
Electromagnetic, attracted and induction type relays, thermal relay, gas actuated relay, design considerations of electromagnetic relay.
Unit-II: Relay Application and Characteristics:
Amplitude and phase comparators, over current relays, directional relays, distance relays, differential relay.
Static Relays: Comparison with electromagnetic relay, classification and their description, over current relays, directional relay, distance relays, differential relay.
Unit-III Protection of Transmission Line:
Over current protection, distance protection, pilot wire protection, carrier current protection, protection of bus, auto re-closing,
Unit-IV: Circuit Breaking:
Properties of arc, arc extinction theories, re-striking voltage transient, current chopping, resistance switching, capacitive current interruption, short line interruption, circuit breaker ratings.
Testing Of Circuit Breaker: Classification, testing station and equipments, testing procedure, direct and indirect testing.
Unit-V Apparatus Protection:
Protection of Transformer, generator and motor.
Circuit Breaker: Operating modes, selection of circuit breakers, constructional features and operation of Bulk Oil, Minimum Oil, Air Blast, SF6, Vacuum and d. c. circuit breakers.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
Every power supply depends upon a reliable infeed of electricity. Air circuit breakers reliably protect electrical installations against damage or fire as a result of short circuits, ground faults, or overload faults.
An electrical circuit breaker is a switching device which can be operated manually and automatically for controlling and protection of electrical power system respectively. As the modern power system deals with huge currents, the special attention should be given during designing of circuit breaker for safe interruption of arc produced during the operation of circuit breaker.
The modern power system deals with huge power network and huge numbers of associated electrical equipments. During short circuit fault or any other types of electrical fault these equipment as well as the power network suffer a high stress of fault current in them which may damage the equipment and networks permanently.
For saving these equipment and the power networks the fault current should be cleared from the system as quickly as possible. Again after the fault is cleared, the system must come to its normal working condition as soon as possible for supplying reliable quality power to the receiving ends. In addition to that for proper controlling of power system, different switching operations are required to be performed.
So for timely disconnecting and reconnecting different parts of power system network for protection and control, there must be some special type of switching devices which can be operated safely under huge current carrying condition. During interruption of huge current, there would be large arcing in between switching contacts, so care should be taken to quench these arcs in circuit breaker in safe manner. The circuit breaker is the special device which does all the required switching operations during current carrying condition.
Industrial Star Delta Starter for a 3-Phase Induction Motorelprocus
The most basic feature of an Induction motor is its self starting mechanism. Due to the rotating magnetic field, an emf is induced in the rotor, because of which current starts flowing in the rotor.
A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.
Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow.
Unit I: Introduction to Protection System:
Introduction to protection system and its elements, functions of protective relaying, protective zones, primary and backup protection, desirable qualities of protective relaying, basic terminology.
Relays:
Electromagnetic, attracted and induction type relays, thermal relay, gas actuated relay, design considerations of electromagnetic relay.
Unit-II: Relay Application and Characteristics:
Amplitude and phase comparators, over current relays, directional relays, distance relays, differential relay.
Static Relays: Comparison with electromagnetic relay, classification and their description, over current relays, directional relay, distance relays, differential relay.
Unit-III Protection of Transmission Line:
Over current protection, distance protection, pilot wire protection, carrier current protection, protection of bus, auto re-closing,
Unit-IV: Circuit Breaking:
Properties of arc, arc extinction theories, re-striking voltage transient, current chopping, resistance switching, capacitive current interruption, short line interruption, circuit breaker ratings.
Testing Of Circuit Breaker: Classification, testing station and equipments, testing procedure, direct and indirect testing.
Unit-V Apparatus Protection:
Protection of Transformer, generator and motor.
Circuit Breaker: Operating modes, selection of circuit breakers, constructional features and operation of Bulk Oil, Minimum Oil, Air Blast, SF6, Vacuum and d. c. circuit breakers.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
Every power supply depends upon a reliable infeed of electricity. Air circuit breakers reliably protect electrical installations against damage or fire as a result of short circuits, ground faults, or overload faults.
An electrical circuit breaker is a switching device which can be operated manually and automatically for controlling and protection of electrical power system respectively. As the modern power system deals with huge currents, the special attention should be given during designing of circuit breaker for safe interruption of arc produced during the operation of circuit breaker.
The modern power system deals with huge power network and huge numbers of associated electrical equipments. During short circuit fault or any other types of electrical fault these equipment as well as the power network suffer a high stress of fault current in them which may damage the equipment and networks permanently.
For saving these equipment and the power networks the fault current should be cleared from the system as quickly as possible. Again after the fault is cleared, the system must come to its normal working condition as soon as possible for supplying reliable quality power to the receiving ends. In addition to that for proper controlling of power system, different switching operations are required to be performed.
So for timely disconnecting and reconnecting different parts of power system network for protection and control, there must be some special type of switching devices which can be operated safely under huge current carrying condition. During interruption of huge current, there would be large arcing in between switching contacts, so care should be taken to quench these arcs in circuit breaker in safe manner. The circuit breaker is the special device which does all the required switching operations during current carrying condition.
Industrial Star Delta Starter for a 3-Phase Induction Motorelprocus
The most basic feature of an Induction motor is its self starting mechanism. Due to the rotating magnetic field, an emf is induced in the rotor, because of which current starts flowing in the rotor.
A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.
Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow.
It describes about the circuit breaker and components and types of high voltage circuit breaker. It also explains about the working principle of the circuit breaker.
Switchgear and protection lecture 2 type of circuit breakers and applicationsanuphowlader1
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow.
Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.
https://www.youtube.com/channel/UC2SvKI7eepP241VLoui1D5A
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.
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.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
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.
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.
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.
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.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
1. CIRCUITBREAKERS
Content
SF6 Circuit breakers
Vacuum Circuit breakers
Prepared By
Mr.K.Jawahar, M.E.,
Assistant Professor
Department of EEE
Kongunadunadu College of Engineering and Technology Depar tment of EEE
Circuit Breakers
2. Sulphur Hexafluoride (SF6) Circuit breakers
• In such circuit breakers, sulphur hexafluoride (SF6) gas is used as
the arc quenching medium. The SF6 is an electro-negative gas
and has a strong tendency to absorb free electrons. The contacts
of the breaker are opened in a high pressure flow of SF6 gas and
an arc is struck between them.
• The conducting free electrons in the arc are rapidly captured by
the gas to form relatively immobile negative ions.
• This loss of conducting electrons in the arc quickly builds up
enough insulation strength to extinguish the arc.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
3. Construction.
• It consists of fixed and moving contacts enclosed in a chamber
(called arc interruption chamber) containing SF6 gas.
• This chamber is connected to SF6 gas reservoir. When the contacts
of breaker are opened, the valve mechanism permits a high
pressure SF6 gas from the reservoir to flow towards the arc
interruption chamber.
• The fixed contact is a hollow cylindrical current carrying contact
fitted with an arc horn.
• The moving contact is also a hollow cylinder with rectangular
holes in the sides to permit the SF6 gas to let out through these
holes after flowing along and across the arc. The tips of fixed
contact, moving contact and arcing horn are coated with copper-
tungsten arc resistant material.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
5. Working:
• In the closed position of the breaker, the contacts remain
surrounded by SF6 gas at a pressure of about 2.8kg/cm.
• When the circuit breaker operates, the moving contact is pulled
apart and an arc is struck between the contacts.
• The movement of the moving contact is synchronized with the
opening of a valve which permits SF6 at 14kg/cm pressure from
the reservoir to the arc interruption chamber.
• The high pressure flow of SF6 rapidly absorbs the free electrons
in the arc path to form immobile negative ions which are
ineffective as charge carriers.
• The result is that the medium between the contacts quickly builds
up high dielectric strength and causes the extinction of the arc.
• After the breaker operation (i.e., after arc extinction), the valve is
closed by the action of a set of springs.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
6. Advantages.
(i) Due to the superior arc quenching property of SF6, such circuit
breakers have very short arcing time.
(ii) Since the dielectric strength of SF6 gas is 2 to 3 times that of air,
such breakers can interrupt much larger currents.
(iii) The SF6 circuit breaker gives noiseless operation due to its
closed gas circuit and no exhaust to atmosphere unlike the air
blast circuit breaker.
(iv) There is no risk of fire in such breakers because SF6 gas is non-
inflammable.
(v) There are no carbon deposits so that tracking and insulation
problems are eliminated.
(vi) The SF6 breakers have low maintenance cost, light foundation
requirements and minimum auxiliary equipment.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
7. Disadvantages
(i) SF6 breakers are costly due to the high cost of SF6.
(ii) Since SF6 gas has to be reconditioned after every operation of the
breaker, additional equipment is required for this purpose.
Applications.
A typical SF6 circuit breaker consists of interrupter units each
capable of dealing with currents upto 60 kA and voltages in the
range of 50-80 kV.
A number of units are connected in series according to the
system voltage. SF6 circuit breakers have been developed for
voltages 115 kV to 230 kV, power ratings 10 MVA to 20 MVA
and interrupting time less than 3 cycles.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
8. Vacuum Circuit Breakers (VCB)
• In such breakers, vacuum (degree of vacuum being in the range
from 10 to 10 torr) is used as the arc quenching medium. Since
vacuum offers the highest insulating strength, it has far superior
arc quenching properties than any other medium.
Principle.
When the contacts of the breaker are opened in vacuum (10 to 10
torr), an arc is produced between the contacts by the ionization of
metal vapours of contacts*.
However, the arc is quickly extinguished because the metallic
vapours, electrons and ions produced during arc rapidly condense
on the surfaces of the circuit breaker contacts, resulting in quick
recovery of dielectric strength.
As soon as the arc is produced in vacuum, it is quickly
extinguished due to the fast rate of recovery of dielectric strength
in vacuum.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Department of EEE
9. Construction.
• It consists of fixed contact, moving contact and arc shield
mounted inside a vacuum chamber. The movable member is
connected to the control mechanism by stainless steel bellows.
• This enables the permanent sealing of the vacuum chamber so as
to eliminate the possibility of leak. A glass vessel or ceramic
vessel is used as the outer insulating body.
• The arc shield prevents the deterioration of the internal dielectric
strength by preventing metallic vapours falling on the inside
surface of the outer insulating cover.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
11. Working.
When the breaker operates, the moving contact separates from
the fixed contact and an arc is struck between the contacts.
The production of arc is due to the ionization of metal ions and
depends very much upon the material of contacts.
The arc is quickly extinguished because the metallic vapours,
electrons and ions produced during arc are diffused in a short
time and seized by the surfaces of moving and fixed members
and shields.
Since vacuum has very fast rate of recovery of dielectric strength,
the arc extinction in a vacuum breaker occurs with a short contact
separation (say 0·625 cm).
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
12. Advantages
(i) They are compact, reliable and have longer life.
(ii) There are no fire hazards.
(iii) There is no generation of gas during and after operation.
(v) They require little maintenance and are quiet in operation.
(vi) They can successfully withstand lightning surges.
(vii) They have low inertia and hence require smaller power for control
mechanism.
Applications.
For a country like India, where distances are quite large and accessibility
to remote areas difficult, the installation of such outdoor, maintenance
free circuit breakers should prove a definite advantage.
Vacuum circuit breakers are being employed for outdoor applications
ranging from 22 kV to 66 kV. Even with limited rating of say 60 to 100
MVA, they are suitable for a majority of applications in rural areas.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
13. Circuit breaker rating
• A circuit breaker may be called upon to operate under all
conditions. However, major duties are imposed on the circuit
breaker when there is a fault on the system in which it is
connected.
• Under fault conditions, a circuit breaker is required to perform
the following three duties :
(i) It must be capable of opening the faulty circuit and breaking the
fault current.
(ii) It must be capable of being closed on to a fault.
(iii) It must be capable of carrying fault current for a short time
while another circuit breaker (in series) is clearing the fault.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
14. The circuit breakers have three ratings viz.
(i) breaking capacity (ii) making capacity and (iii) short-time capacity.
(i) Breaking capacity. It is current (r.m.s.) that a circuit breaker is
capable of breaking at given recovery voltage and under specified
conditions (e.g., power factor, rate of rise of restriking voltage).
(ii) Making capacity
The peak value of current (including d.c. component) during the first
cycle of current wave after the closure of circuit breaker is known as
making capacity.
(iii) Short-time rating. It is the period for which the circuit breaker is able
to carry fault current while remaining closed.
• Normal current rating. It is the r.m.s. value of current which the circuit
breaker is capable of carrying continuously at its rated frequency under
specified conditions. The only limitation in this case is the temperature
rise of current-carrying parts.
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE
15. Reference:
• V.K.MEHTA,ROHIT MEHTA, “Principles of Power
System”, S.Chand,2018.
• B.Rabindranath and N.Chander, ‘Power System Protection
and Switchgear’, New Age International (P) Ltd., First
Edition 2011.
15
Circuit Breakers
Kongunadunadu College of Engineering and Technology Depar tment of EEE