1. The document discusses the testing of high voltage circuit breakers. Digital testing employs software to simulate circuit breaker performance based on characteristic measurements from standard tests.
2. High resolution current and voltage measurements are made around current zero crossing to characterize breaker behavior. An empirical arc model is validated and used to predict test outcomes.
3. The software can be used to study the influence of system components on breaker performance and determine critical line lengths for short line faults by simulating different test circuits digitally.
Technical Seminar On Digital testing of high voltage circuit breaker seminar for final year Electrical Engineering students. It cover all the points which need to be covered for the technical seminar. For more information and report, contact me on my mail mentioned on first page of ppt
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.
Technical Seminar On Digital testing of high voltage circuit breaker seminar for final year Electrical Engineering students. It cover all the points which need to be covered for the technical seminar. For more information and report, contact me on my mail mentioned on first page of ppt
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.
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.
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.
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.
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.
This PPT explains about the circuit breaker, and its types. Then about the need and purpose of the circuit breaker. And finally the testing and types of testing of circuit breakers.
This Presentation is about l.v switch gear design, presented during the graduation project final discussion 15/7/2018.
It presented a good summary of switch gear components and types and practicing on AL.HAMOOL W.T.P M.D.B design using SIEMENS SIVACON S8
The circuit breaker plays an important role in providing over-current protection and a disconnect means in electrical networks. Recent advancements in circuit breaker technology has increased breaker performance and protection.
https://topelectricaldevices.com/what-is-circuit-breaker-top-5-best-mcb/
The circuit breaker plays an important role in providing over-current protection and a disconnect means in electrical networks. Recent advancements in circuit breaker technology has increased breaker performance and protection.
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.
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.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
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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.
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.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
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.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
Quality defects in TMT Bars, Possible causes and Potential Solutions.
DIGITAL TESTING OF HIGH VOLTAGE CIRCUIT BREAKER
1. 1
CONTENTS
INTRODUCTION 01
ESSENTIAL QUALITIES OF A HIGH VOLTAGE 02
CIRCUIT BREAKER
HISTORY 03
THE NEED FOR TESTING 04
TESTING OF CIRCUIT BREAKERS 05
CIRCUIT BREAKER SWITCHING AND ARC MODELING 07
DIGITAL TESTING 08
MEASUREMENT AND DATA ANALYSIS 09
ARC-CIRCUIT INTERACTION SOFTWARE 13
APPLICATIONS OF DIGITAL TESTING 15
INFLUENCE OF PARALLEL CAPACITANCE 15
CRITICAL LINE LENGTH DETERMINATION 16
ADVANTAGES & DISADVANTAGES 18
CHALLENGES 18
CONCLUSION 19
REFERENCES 20
2. 2
ABSTRACT
The functionality of high voltage circuit breaker is tested in high power
laboratories. With the advancement of power system need for high voltage circuit breaker
has increased a lot, as they play an important role in transmission and distribution. Among
the tests, Routine tests are performed on every piece of circuit breaker in the premises of
the manufacturer. where Type tests are performed in a high voltage laboratory. The test is
performed on sample pieces of circuit breaker of each type to confirm their characteristics
and rated capacities according to their design. Digital testing of high voltage circuit
breaker employs a software product for testing of a breaker model, once its characteristic
fingerprints are obtained from the standard tests. High-resolution measurements of current
and voltage are done in the critical period. The arc voltage is measured with standard
broadband RCR type voltage divider and current with special Rogows.
3. 3
INTRODUCTION
With the advancement of power system, the lines and other equipment operate at
very high voltages and carry large currents. High-voltage circuit breakers play an
important role in transmission and distribution systems. A circuit breaker can make or
break a circuit, either manually or automatically under all conditions viz. no-load, full-load
and short-circuit conditions. The American National Standard Institute (ANSI) defines
circuit breaker as: “A mechanical switching device capable of making, carrying and
breaking currents under normal circuit conditions and also making, carrying for a specified
time, and breaking currents under specified abnormal circuit conditions such as those of
short circuit”. A circuit breaker is usually intended to operate infrequently, although some
types are suitable for frequent operation.
4. 4
ESSENTIAL QUALITIES OF HV CIRCUIT BREAKER
High-voltage circuit breaker play an important role in transmission and
distribution systems. They must clear faults and isolate faulted sections rapidly and
reliably. In-short they must possess the following qualities.
In closed position they are good conductors.
In open position they are excellent insulators.
They can close a shorted circuit quickly and safely without unacceptable contact
erosion.
They can interrupt a rated short-circuit current or lower current quickly without
generating an abnormal voltage.
The only physical mechanism that can change in a short period of time from a
conducting to insulating state at a certain voltage is the arc.
5. 5
HISTORY
The first circuit breaker was developed by J.N. Kelman in 1901. It was the
predecessor of the oil circuit breaker and capable of interrupting a short circuit current of
200 to 300 Ampere in a 40KV system. The circuit breaker was made up of two wooden
barrels containing a mixture of oil and water in which the contacts were immersed. Since
then the circuit breaker design has undergone a remarkable development. Now a days one
pole of circuit breaker is capable of interrupting 63 KA in a 550 KV network with SF6 gas
as the arc quenching medium.
6. 6
THE NEED FOR TESTING
Almost all people have experienced the effects of protective devices operating
properly. When an overload or a short circuit occurs in the home, the usual result is a
blown fuse or a tripped circuit breaker. Fortunately few have the misfortune to see the
results of a defective device, which may include burned wiring, fires, explosions, and
electrical shock.
It is often assumed that the fuses and circuit breakers in the home or industry are
infallible, and will operate safely when called upon to do so ten, twenty, or more years
after their installation. In the case of fuses, this may be a safe assumption, because a
defective fuse usually blows too quickly, causing premature opening of the circuit, and
forcing replacement of the faulty component. Circuit breakers, however, are mechanical
devices, which are subject to deterioration due to wear, corrosion and environmental
contamination, any of which could cause the device to remain closed during a fault
condition. At the very least, the specified time delay may have shifted so much that proper
protection is no longer afforded to devices on the circuit, or improper coordination causes
a main circuit breaker or fuse to open in an inconvenient location.
7. 7
TESTING OF CIRCUIT BREAKERS
The design of circuit breaker is not only a science but also an art. Because of the
complex phenomena involved, circuit breaker prototypes have to be verified by practical
tests in the laboratory. There are two types tests of circuit breakers, namely Routine tests
and Type tests. Routine test are performed on every piece of circuit breaker in the premises
of the manufacturer. The purpose of the routine test is to confirm the proper functioning of
a circuit breaker. Type tests are performed in a high voltage laboratory; such tests are
performed on sample pieces of circuit breaker of each type to confirm their characteristics
and rated capacities according to their design. These tests are not performed on every piece
of the circuit breaker. All routine and type tests are performed according to Indian
Standard (IS) codes, or International Electromechanical Commission (IEC) codes or
British Standard (BS) codes.
In High-power laboratories the ability of the circuit breakers to interrupt the
circuit currents is verified in test circuits which is infact the lumped element representation
of the power system. These test circuits must produce the corrected forms of the short
circuit current as well as the final voltage that strikes the circuit breaker immediately after
the breaker has interrupted the test current. The forms of voltage and current to which the
test object must be subjected are laid down in ANSI and International Electromechanical
commission (IEC) standards. These standardized waveform represent 90% of the possible
conditions in the real system.
9. 9
CIRCUIT BREAKER SWITCHING AND ARC MODELLING
The switching action, the basic function of the circuit breaker refers to the
change from conductor to insulator at a certain voltage. Before interruption, the short
circuit flows through the circuit breaker arc channel. Because of non zero resistance of the
channel , the short circuit current causes a voltage across the contacts of the circuit
breaker; the arc voltage. The arc behaves as a non-linear resistance. Thus both are voltage
and arc current cross the zero value at the same time instant. If the arc is cooled at the time
current goes through zero the circuit breaker interrupts the current because the electrical
power input is zero. During current interruption, the arc resistance increases practically
from zero to almost infinity in microseconds. Immediately after current interruption, the
transient recovery voltage builds up across the circuit breaker .As the gas mixture in the
interelectrode space does not change to a completely insulating state instantaneously, the
arc resistance is finite at that time and a small current can flow ;the post –arc current.
Black box arc models are mathematical description of the electrical properties of
the arc .This type of model does not simulate the complicated physical processes inside the
circuit breaker but describes the electrical properties of the circuit breaker. Measured
voltage and current traces are used to extract the parameters for the differential equations
describing the nonlinear resistance of the electrical arc for that specific measurement.
10. 10
DIGITAL TESTING
The functionality of high-voltage circuit breakers is tested in high-power
laboratories. Due to the necessary power and the physical size of the equipment , testing is
rather expensive and time consuming. In order to obtain as much information as possible
about the degradation and operating of the circuit breaker from cost intensive tests, a
project started with the following parties.
1. KEMA high power laboratories The Netherlands.
2. Delft University of technology, The Netherlands.
3. Siemens AG, Germany
4. RWE Energy ,Germany
The project is aimed at developing digital testing of high-voltage circuit
breakers. ie., a software product for testing a model of such a device , once its
characteristic fingerprints are obtained from refined measurements during standard tests.
Digital offers a wide range of new possibilities for users, manufactures, standardizing
bodies and test laboratories for fine tuning circuit breaker abilities in relation with standard
and real power systems. The steps followed so far to enable digital testing are described in
the following section.
11. 11
MEASUREMENT AND DATA ANALYSIS
High resolution measurements of current and voltage in the critical period
around short circuit current zero must supply the necessary parameters characterizing the
breaker’s behaviour. A tailor-made high-frequency measuring system was realized for this
purpose. This system consists a number of battery powered, single channel 40MHz 12bit
AD converters each storing data temporarily in on board local RAM (256k samples each).
The concept of on-site data storage is necessary for reaching a maximum overall system
bandwidth. Cables to the current and voltage sensors can thus be kept very short and the
system can operate on floating potential. The arc voltage is measured with standard broad
band RCR type voltage dividers. Current is measured with a special Rogowski coil. After
the remote RAM is filled, data is transmitted serially through optical fibres to the
processing unit in the command centre. The greatest challenge with respect to developing
the equipment in this application design lies in the electromagnetic compatibility, since the
microelectronics has to function in an extremely hostile environment of intense Electro
Magnetic fields of various origin.
The system relies heavily on digital signal processing methods for
reconstructing the actual voltage and current signals from the raw sensor output. On the
one hand, this has to do with the specific frequency sensors and on the other hand, with
corrections needed for the reproducible induced voltage and capacitive current that distort
the measured signals. Tests in various laboratories have proven that the system can
measure post-arc current as small as 50 mA, microseconds after the interruption of many
tens of kA.
12. 12
Figure 1. Voltage and current measurement data
Data analysis software has been produced to carry out the signal reconstruction
practically on line during the tests (Figure-1) and to evaluate the performance of the test
object. Even the newest professional multipurpose mathematical or laboratory software is
not competitive to this custom-made software considering flexibility and speed in
visualizing and data processing of practically unlimited amount of measured data in a user
friendly way.
After an extensive series of the most critical fault interruption duty for circuit
breakers, a test data-base from various types of commercially available circuit breakers
was set up. With this experimental material, an empirical arc model based on classical arc
models was validated that gave very good coverage of the observed processes. From the
total number (more than 250) interruption attempts, the result of the attempt i.e., failure or
13. 13
success was predicted correctly in more than 90% of the cases by evaluating the
characteristics of the arc behaviour with model.
Figure 2 Parameter extraction software
The model has a set of three parameters, which are extracted automatically
during the evaluation of each test. See figure 2. Automated analysis of the collection of all
the parameter sets (in other. words the breaker’s finger prints) obtained from a whole
series of tests makes it possible to evaluate various physical quantities as a function of test
conditions.
The aim of using this method is to quantify the breaker performance (the margin
of interruption M), indicating how successful the breaker passed the test (M>O) or how far
it is off from passing it (M<O).
14. 14
An example is given in Figure 3 where the degradation of the three breaker poles
(A,B and C) is presented during a sequence of successive tests. It can be seen clearly that
the margin of the breaker decreases with every test. The rate of margin decay (among
others) is a measure of the endurance of the breaker with respect to this type of tests.
Figure 3. Degradation of the circuit breaker poles
15. 15
ARC-CIRCUIT INTERACTION SOFTWARE
At the final stage of the realization of digital testing, measured arc model
parameters will be used as input for the arc model. Of course, this arc model behaves as a
non-linear element in the electrical circuit and must therefore be analyzed with a dedicated
computer program. The analysis of arc-circuit interaction involving non linear elements in
relation to stiff differential equations makes it necessary to perform the calculations with a
variable step size and adjustable accuracy of the computed currents, voltages and
conductances. Because they have fixed step-size solvers, EMTP and comparable programs
are less suitable for this purpose and therefore a new approach, the integration of
differential algebraic equations (DAE) by means of the backward differentiation formula
(BDF) method has been chosen in developing a new software package for electrical
transients computation. This new transient program, X Trans has been developed at the
Delft University of Technology especially for arc-circuit interaction studies. The program
runs on a PC with the MS-Windows operating system and works fully graphical as shown
in figure 4. The program is in use at several high-power and high-voltage laboratories in
the world.
16. 16
Figure 4.XTrans transient program
The program makes use of libraries that contain information about the behaviour
of element models. The program structure is depicted in figure 5. The structure has been
realized with object oriented programming. The compiled code of the element models is
placed in dynamic link libraries (DLL). The models are therefore separate from the main
program, which makes it easy to create new models and use them in the main program.
17. 17
Figure 5. Structure of the XTrans transient program
APPLICATIONS OF DIGITAL TESTING
1. INFLUENCE OF PARALLEL CAPACITANCE
Powerful possibilities with digital testing are created when the arc model,
validated as described in the section on Measurements and Data Analysis is coupled with a
circuit analysis package. Then the performance of a circuit breaker, the fingerprints of
which are obtained from real tests can be estimated in circuits other than the test circuit.
For example, the influence of various standard substation components on the
breaker’s capabilities can be estimated through digital testing.
Here the influence of a parallel capacitance is calculated (for example, the
parasitic capacitance of a current transformer, CT) in the substation.
In Table 1, the performance of a short-line fault interruption is compared in the
presence of two types of CTs; CT1 having 200 pF of parasitic capacitance and CT2 having
400 pF. These CTs can be located near the circuit breaker or remote to the breaker (the
latter implying an additional 50 microhenry of bus bar between CT and breaker). As a
reference the case without CT has a performance of 1.0.
18. 18
Table 1 shows that the difference between the two types of CTs is rather small
when compared to gain obtained by the CT that was installed to the breaker as closely as
possible.
Table 1. Influence of a current transformer
2. CRITICAL LINE LENGTH DETERMINATION
One of the most severe currents for a circuit breaker to interrupt is the short line
fault (SLF). In the case of a short-line fault, the short circuit point is on a high voltage
transmission line a few kilometers away from the breaker terminals. After current
interruption a very steep triangular-shaped waveform (with a rate of rise of 5-10
KV/microsecond) stresses the extinguishing medium between the contacts. The percentage
SLF indicates to what extent, the short circuit current is reduced by the transmission line.
Eg. a short circuit current of 40KA is reduced to 36KA in case of a 90% SLF. In the IEC
standard, 75% and 90% SLF tests are prescribed.
Figure 6. A direct SLF test circuit in the XTrans program
19. 19
As an example of digital testing, the critical line length, the short line fault
percentage that stresses the circuit breaker most, will be determined for a 145KV, 31.5KA
SF6 circuit breaker. A direct SLF test circuit is shown in Figure 6. Three different
indicators active at different time intervals (before current zero, at current zero and after
current zero) are used to quantify the stress on circuit breaker model.
Before current zero:- The time before current zero where the arc resistance equals
the surge impedance of the transmission line t (R=Z) The closer the value is to
current zero, the more severe the breaker is stressed by the test circuit.
At current zero:- The arc resistance is R0. The lower the arc resistance value at the
current zero crossing, the stronger the breaker is stressed by the test circuit.
After current zero:- The post arc energy is Epa. This value is the integral of the
multiplication of the small post-arc current and the recovery voltage. It is clear that
only for successful interruptions an Epa value can be calculated. The higher the
Epa value is, the more severe the breaker is stressed by the test circuit.
The actual computation is based on 75 current zero recordings of the circuit
breaker of which the circuit breaker model parameters have been determined. For each set
of parameters, the stresses at various short line fault percentages is computed. At last the
overall stress is visualized which is shown in Figure 7.
Figure 7. Critical line length determination by means of digital testing
All three indicators show that the circuit breaker model is stressed most severely
at a 93% SLF, whereas a 90% SLF is prescribed in the IEC standard. This shows that
20. 20
digital testing can be applied to use the information obtained from laboratory tests for the
development of future standards.
ADVANTAGES OF DIGITAL TESTING
Evaluation of relevance of future standards with respect to real power systems.
Evaluation of the relevance of future standards for different circuit breaker
technologies and extinguishing media.
Estimation of circuit breaker’s interrupting limit.
Reduction of full scale testing in high-power laboratories.
Identification of network topologies that can pose special difficulties to a circuit
breaker.
Acceleration at development of new circuit breaker design.
Monitoring the aging process of circuit breaker in service.
Expansion of services for high-power laboratories
DISADVANTAGE OF DIGITAL TESTING
Testing in costlier
CHALLENGES
Micro electronic instruments for sensing and measuring the parameters are kept in
intense magnetic fields.
CONCLUSION
Digital testing gives precise information about the breaker, as obtained from
laboratory tests. This is useful for the development of future standards. Powerful
21. 21
possibilities with digital testing are created when arc model and data analysis is coupled
with a circuit analysis package. The performance of a circuit breaker whose finger prints
are obtained from real tests can be estimated in other circuits also.
22. 22
REFERENCES
1. “Digital testing of high voltage circuit breakers” by Pieter Schavemaker, Lou
vandersluis, IEEE Computer Applications in Power, April 2000.
2. “Evaluation of H.V. Circuit breaker performance with a new arc model” by
R.P.P. Smeets, V. Kertesz, lEE Proceedings on generation Transmission and
Distribution.
3. Circuit breaker testing technology by Paul E. Schoen, President PS Technology,
Inc. March 26, 1997.