Sergio Feitoza Costa - Academia.edu (original) (raw)

Papers by Sergio Feitoza Costa

Tabela 6 IEC 61439-1: PERGUNTA a CERTIFICADORAS e LABORATORIOS de TESTES: Que limites de elevação de temperatura, em conexões barra / disjuntor, utilizam ao aprovar ou certificar painel BT ? , 2023

IDÉIA para C I G R È internacional e P&D ANEEL : AVALIAR QUANTO PODEM SER AUMENT... more IDÉIA para C I G R È internacional e P&D ANEEL : AVALIAR QUANTO PODEM SER AUMENTADOS OS LIMITES DE ELEVAÇÃO de TEMPERATURA USADOS nas NORMAS IEC e ABNT .

Certificadoras e laboratórios de testes: precisam usar os valores limites da Tabela 6 para poder aprovar ou certificar o equipamento. Limites nas conexões – o ponto mais quente – não estão escritos. Como procedem diante do texto indefinido ?
Relatorio de testes sem conclusão “aprovado / reprovado” ? sendo 3ª parte possivelmente vai fazer o usuário pensar que passou. Esperam que o usuário avalie lendo a tabela ?
Seguradoras e responsabilidades: p.ex. se ocorre incêndio ou perda por envelhecimento acelerado, devido a uso acima de limites reconhecidos, quem é responsável, do ponto de vista de seguradoras ?
Frase “Conforme requisitos da norma de componente ou instruções do fabricante” induz ao erro: não é declaração objetiva nem verificável (ISO9000). Limites de conexões dependem só dos materiais.
Quais os limites corretos a aplicar: há uma conexão entre disjuntor principal (85K) e seu barramento de alimentação (60/75K). Pelas regras de engenharia, o limite é o menor dos dois valores – e não o valor do disjuntor/ componentes (IEC60943). Porque conceito da nota (b) vale só para terminais ?.
Menção a 105 K induz o leitor a pensar que este é o valor limite das conexões: parece que confundiram, no passado, o termo “temperatura (40+75=115K) com “temperatura” e passou a ser a “verdade”.
SOLUÇÃO: substituir Tabela 6 da IEC61439-1 pela transparente Tabela 14 da IEC62271-1 .

Table 6 of IEC 61439-1: QUESTION to CERTIFIERS & TESTING LABORATORIES: -- What temperature rise limits, in bar/breaker connections, to use when approving or certifying low voltage switchgear? , 2023

With a suggestion to Cigrè • Certifiers & testing laboratories: need to use the limit values in ... more With a suggestion to Cigrè

• Certifiers & testing laboratories: need to use the limit values in Table 6 to be able to approve or certify tested equipment. Limits for connections, the hotspot, are not written. How to deal with undefined text?
• Test report without “pass/fail” conclusion are frequent in the market: If the lab is 3rd part, the buyer will possibly think it was approved. Do you expect the user to evaluate by reading the table?
• Insurers and Liabilities: e.g., if fire or loss due to accelerated aging occurs, due to use above recognized limits, who is responsible, from the point of view of insurers?
• The phrase “According to the requirements of the component standard or the manufacturer’s is not an objective or verifiable statement (ISO9000). Connection limits depend only on the materials.
• What are the correct temperature rise limits to apply: suppose a connection between main breaker (85K) and the busbar (60/75K). By engineering rules, the limit is the lower of the two values – not the breaker/component value (IEC60943). Why is the concept of note (b) valid only for terminals?
• Mention of 105 K leads to wrong thinking that this is the limit value of connections: seems that, in the past, the term “temperature (40+75=115K) was confused with “temperature” and it became the “truth”.
• SOLUTION: replace the poorly written Table 6 IEC 61439-1 by the transparent Table 14 of IEC62271-1.

About electric showers & technical stamdards like IEC61439-1

About damages in electric showers

Queima de chuveiros eletricos, 2023

A respeito de queima frequente de chuveiros eletricos

EC 60282-2-High-voltage fuses-Part 2: Expulsion Fuses Suggestions to SC32A for next revision, 2023

IEC 60282-2-High-voltage fuses-Part 2: Expulsion Fuses Suggestions to SC32A for next revision. Ab... more IEC 60282-2-High-voltage fuses-Part 2: Expulsion Fuses Suggestions to SC32A for next revision. About aging of fuse links, concepts of IEC62271-307 and identification of what was tested.

IEC 61439: The Mystery of the Temperature Rise Limits, 2019

• Was your low voltage switchgear approved in the temperature rise test? • Is this written in the... more • Was your low voltage switchgear approved in the temperature rise test?
• Is this written in the test report or you have a “quality system” weak point?
• An alert to low-voltage switchgear buyers

This article is about a deficiency in IEC 61439 standard that impacts the worldwide market of low-voltage switchgear. It is related to the temperature rise test in low-voltage switchgear. As most of the limits of temperature rise are not specified in the standard, testing laboratories usually do not say in the tests reports if the equipment was approved or not. So, possibly many people buy equipment that failed in the test and simply do not know this. Also, this is an open door for unfair competition in the market. A suggestion to IEC standard makers is included in the article.

FINDING THE OPTIMAL DESIGN USING SIMULATIONS (Aluminum x Copper) (Try to do it with real lab high power tests, 2019

This is an update of a 2014 article written by me and my colleague Marlon F. de Campos. The 3 mos... more This is an update of a 2014 article written by me and my colleague Marlon F. de Campos. The 3 most expensive requirements in the design of cubicles, panels and busducts are:
• the temperatures which shall not be over passed during normal operation to avoid premature ageing,
• The supportability to the overpressures caused by internal arcs with risks to persons and installations.
• The supportability to the forces on insulators and conductors produced by short circuit currents.

For example, the effects of electrodynamical forces depend on the distances between phases (D1 – Fig.1) and between supports (D2). A smaller D2 makes the system mechanically stronger but more onerous due to higher expenses with supports and mounting. Using a bus bar with a bigger cross section brings higher supportability but also higher expenses with copper or aluminum. The designer goal is to find the optimum point considering the objective to reach (cheaper, safer, etc…). To do it with real tests is very expensive. To do it with computer tools for testing simulations (as SwitchgearDesign), is a question of few hours, for experienced designers.

To find the optimal design several technical and economic variables shall be considered. When manufacturers develop a product, they know that, at least at the end of the process, they will need to do onerous and time-consuming high-power tests at a testing laboratory. Manufacturers frequently oversize the design to avoid the risk of failures in the tests. This is in the opposite direction of an optimized design.

The objective of this paper is to show how to obtain optimized products using less aluminum or copper, fewer insulators, less tests and maintaining the quality. We included a test case to compare the use of aluminum and copper to attend the requirements of a specific project. The switchgear dimensions of the test case (Figures 1 and 2) were chosen to represent a small size product. This was done to enable to use a very small lab to compare if the test results and simulation results are close. The effects of temperature rise, electrodynamical forces and internal arc overpressures are more severe if the enclosure volume is smaller. By the way, the idea of a TRIAXIAL switchgear exposed in the Reference [2] is a good thing to be understood by manufacturers which are looking for innovations.

ACCEPTING SIMULATIONS TO REPLACE HIGH POWER TESTS, 2019

It is a well-known fact in world-class development banks such as the World Bank that the electric... more It is a well-known fact in world-class development banks such as the World Bank that the electrical industry, being the most organized of infrastructures, is the fastest way to increase the degree of development of countries. Basic electrification programs show this.

Imagine that you deploy in the country, focusing on the overall development and not just the individual investment, a testing laboratory able to perform high-power tests up to 250 MVA for 3 seconds, temperature rise tests up to 8000A, and, the most important, having a well-trained staff of 10 people. Train this team for, in addition to do the commercial tests, to have abilities to simulate such tests and to know concepts of equipment design. Create regulations to qualify and certify electrical products which clearly states “Do preferably in the country the tests that can be done in the country. Tests which cannot be done in the country may be replaced by simulations under clear rules and responsibilities"

This small-medium size laboratory would be affordably accessible to developing countries. It would be deployed in 3 to 4 years to be the master spring that, in less than 10 years, would consolidate a good electrical industry of line and substation components. It would need government support (only for regulations and technical standards) and local industry support (management and 70% of investment).

The new thing and key for the success is the short regulation and a technical standard to qualify, certify and to commercialize electrical products. The openings for the use of test simulations in substitution of real higher power tests would make the industry to move. Developed countries and those that already have laboratories would continue to use theirs. However, those in developing countries who would implement it would make a great leap in the size and quality of the electric industry.

I saw this movie before, and I can help to explain better each step. For the electric sector planners of developing countries, the reading of the brochure Cigrè 740 (2018) is a must. The title is "Contemporary Design of Low-Cost Substations in Developing Countries”. Look in this summary and get the whole document in Cigrè site

IEC 61439connections: temperature rise of 10K aboveIEC limit= loss of life 66%, 2019

It is a known factin testing laboratoriesthat, when doing a temperature rise tests in low voltage... more It is a known factin testing laboratoriesthat, when doing a temperature rise tests in low voltage switchboards, most frequently, the critical point is the temperature rise of the connections betweenthe circuit breaker and the busbars(points B, C and D of Figure1).In 2017-2018, I wrote to IEC experts askinga doubt on the unclear In 2017-2018, I wrote to IEC experts askinga doubt on the unclear temperature rise limits specified in IEC 61439. I did not receive an enlightening answer about the limits. Then I wroteand postedan articlehoping to get an answer.I am trying once more with this new article(see the previous one in the References)

TRIAXIAL high current AIS - GIS: disclosing an idea worldwide use !,, 2019

In this article I disclose an idea for an alternative design to be used in “air insulated switchg... more In this article I disclose an idea for an alternative design to be used in “air insulated switchgear” (AIS) and “gas insulated switchgear” (GIS). The idea is based in two facts:
a) observing the performance of triaxial cables used in measuring circuits of high-power testing laboratories (before the wider use of optical fibers) and,
b) the practical experience, as a high-power testing engineer, of using along 15 years, in short circuit tests 63kA - 3s, homemade coaxial conductors (copper cables inside an aluminum tube 6” IPS with lengths 40 m). The objective was having low inductance circuits to reach higher short circuit test currents. This is the dream of “high power testing engineers”
The idea is based on the real use of something of the same nature, used in the real life. The intention is to disclose the concepts of this technology for use all over the World. I became motivated to write about this when collaborating with Cigrè WG B3-43 to write the brochure Cigre 740 - Contemporary Design of Low-Cost Substations in Developing Countries (2018).
I am in the direction of validating the results of the simulations using laboratory test results.

IEC technical standards are powerful documents providing directions for specifications, tests and... more IEC technical standards are powerful documents providing directions for specifications, tests and types of equipment which will be commercialized in the Worldwide market. I learned this during my 40 years of activities in the electrical sector. I had the honor of collaborating actively in IEC working groups (WG) including coordinating a WG which prepared a revision of the IEC 60282-2 and, recently, as a member of the WG which prepared IEC 62271-307. In the beginning of the 90’s I was Chairman of the IEC Technical Committee 32 (High Voltage Fuses). I worked 25 years in a high power and high voltage testing lab doing temperature rise tests among many others.

What is written in IEC standards will influence what will happen in the electric products market all over the World. IEC standards are predominantly made by experts from the major international equipment manufacturers. Most of them are in Europe (near the places of the meetings). There are very few participants from small and medium size companies and from outside the developed countries.
In most of the countries, especially the developing ones, the IEC standards are considered almost perfect documents. In many cases they translate those standards to the mother tongue becoming national Standard some 4 year after the publication of the original in English.
Whoever participates in the WGs preparing an IEC publication knows that IEC texts are quite far from a perfect document. They are the text that is possible to reach after the hard discussions in WG meetings. Who invest money and time for participating in the meetings will try to include in the text the points of their interest. Better standards are reached when there is, in the WG, a reasonable balance between manufacturers, testing labs and people that represents the interests of the users. It was like this in the past but in the last 15 years most of the participants in the WGs are the world's largest manufacturers.

It is essential that the IEC text is clear and objective avoiding that the reader need to understand hidden specifications between the lines. The average reader of an IEC publication has much less knowledge and information than the WG members. However, sometimes the texts end up getting confused so that they can contemplate points of view of the participants that cannot be very explicit. The consequence is that the average reader can give a different interpretation of the intent of the standard. Usually these confusions are corrected or improved in the next revision of the IEC text.
This is the central point of this article. IEC60439, from 2011, started to be replaced by the series IEC 61439. It seems that there are significant differences in the temperature rise tests. IEC 61439-1 brought the intelligent concept of design rules. It is a great advance. Could be much better if it was clear that the “design rules” concept are applicable not only to the short circuit aspect but also to temperature rise tests and others.
The recent IEC 62271-307 (medium voltage switchgear), in a certain way, followed the same basic concepts of design rules to avoid repetition of expensive laboratory tests. However, the approach in IEC 62271-307 was more complete covering aspects of short circuit, temperature rise, dielectric tests, mechanical tests and internal arc tests.

In the last two years several of my consultancy clients presented me doubts about requirements in IEC 61439-1. Even being an experient standards reader and having worked 25 years in a testing laboratory, for these types of tests, I had also doubts.

The purpose of this article is to present these doubts (Section 2). When analyzing the doubts, I received a question that I found strange at first. After analyzing the details, I realized that there may be a particularity, when performing temperature rise tests, which may lead to obtaining different test results for the same equipment and the testing conditions. I will describe the reasoning for this in Section3. In the Final Comments (Section4) I present an idea for a common clauses standard applicable to both medium voltage (MV) and low voltage (LV) switchgear.

This article is about costs of technologies, paradigms, use of aluminum, copper, CCA and a patent... more This article is about costs of technologies, paradigms, use of aluminum, copper, CCA and a patent. When a manufacturer is developing a new product, or assessing the feasibility of a new design, in general, needs to base the strategy in technical and economic issues which goes from the considerable prices of using testing labs to the barriers coming from old paradigms superseded by the current knowledge as "using Copper or Aluminum”. In this article, I present an example of development of a new innovative design of a medium voltage air insulated switchgear (AIS) which can be easily transformed in GIS. I am patenting an alternative technology and looking for a manufacturer interested in it. All the initial “development tests” were based in testing simulations and in a long experience in testing laboratories and designing power products.

Concepts on how to calculate electrodynamic forces and stresses which occur during short circuits... more Concepts on how to calculate electrodynamic forces and stresses which occur during short circuits are a must in the design of switchgear, busbar systems in local equipment and in complete substations arrangements. The results of the studies to determine forces and their consequences are used to design structures, size of the busbar conductors, number of insulators and supports, etc.… This paper shows details about this

IEC technical standards are powerful documents providing directions for specifications, tests and... more IEC technical standards are powerful documents providing directions for specifications, tests and types of equipment which will be commercialized in the Worldwide market. I learned this along my 40 years of activities in the electrical sector. Along this time, I had the satisfaction of collaborating in IEC working groups (WG) including coordinating a WG which prepared a revision of the IEC 60282-2 and, recently, a WG that prepared the new published IEC 62271-307.

What is written in IEC standards will influence what will happen all over the World in developed and developing countries. IEC standards are predominantly made by experts from the major international equipment manufacturers from developed countries. There are very few participants from small and medium size companies and from outside the group of developed countries.
This makes, even more important, to have clear texts and to avoid creating specifications and test conditions that will be more difficult to meet than the previous version of an existing standard. This is the central point of this article. IEC60439, for low voltage (LV) switchgear, from 2011, started to be replaced by the series IEC 61439 - Low-voltage switchgear and controlgear assemblies. It seems that there are significant differences on the temperature rise tests.
Some months ago a colleague from a big testing laboratory told me that the lab could do the tests in a LV switchboard according to IEC 60439 but could not do it according to IEC 61439. I told him immediately that he was wrong. However, when I went to read the details of the new IEC 61439 I simply did not understand the big and, at least for me, confusing text. Then I understood the doubt of my lab colleague. I am skilled in reading IEC standards and worked 25 years doing temperature rise tests inclusive by IEC 60439. If I have this doubt certainly many people have this doubt also. If I am right in my interpretation of the IEC 61439 text for temperature rise tests this affects everybody who already did these tests by IEC 60439.
My focus, in this article, is to compare the temperature rise tests specified in both standards. My doubt is if the IEC 61439 added a test requirement much more complicated than the previous IEC 60439. If I understood the writing of IEC 61439, the tests are now more difficult, more time consuming and expensive to do than before. Worse than this, most of the LV switchgear already tested in IEC 60439 would need to be tested again to attend IEC 61439. I would like to be wrong in my interpretation and, for this doubt, I ask for the clarifications from the IEC 61439 standard makers.
So, the objective of this article is to list doubts and get clarifications and not to explain something.

In 2007 Sergio Feitoza wrote the paper PS1-06 “Simulation, IEC Standards & Testing Laboratories” ... more In 2007 Sergio Feitoza wrote the paper PS1-06 “Simulation, IEC Standards & Testing Laboratories” published in the CIGRÈ International Technical Colloquium - Rio de Janeiro. In 2015, another one named “Inducing & Assessing New Technologies & Procedures for The Electric Industry” was published. All of them are in http://www.cognitor.com.br/download.htm

Between these two moments there were advances in IEC and CIGRÈ working groups in themes involving simulations of internal arc tests, temperature rise and other types of expensive tests.

Equipment manufacturers, certification companies and buyers of equipment for substations started to move from the thinking “everything should be tested” to the more pragmatic position "some tests may be replaced by testing simulations" with advantages.

For equipment manufacturers the focus is on predicting laboratory test results to adjust the equipment design to to reduce the probability of failures in the real laboratory test. For certification companies the idea is to use simulations to increase the efficiency in their business. When you certify a product and a modification is done after the emission of the certificate, some tests should be repeated. Simulations done in a comparative sense with a previously tested equipment are very effective for the purposes of a certification company.

Testing laboratories still consider that “everything should be tested”. Twenty years ago, as a manager of big testing laboratories the author of this post was used to think like this. Nowadays he is convinced that this is an error of assessment, after 15 years doing simulations for manufacturers and comparing them with laboratory test results. Laboratories could think that would lose part of the testing market but, on the contrary, “testing simulations” is a very interesting complementary area for them.

In this article there is update information about what changed about the use of testing simulations in the last 10 years. .The complete free version can be downloaded in http://www.cognitor.com.br/Simulations2007_2017.pdf

Author: Sergio Feitoza Costa sergiofeitoza@cognitor.com.br

Site : http://cognitor.com.br/en_home.htm

The electromagnetic fields occurring in substations due to the high currents and high voltages pr... more The electromagnetic fields occurring in substations due to the high currents and high voltages produce different effects on people and objects nearby. High levels of permanent magnetic or electric fields have impacts on the health of people exposed to them. These effects depend on the field strength and duration of exposure. There are specific legislations specifying the maximum values that should not be exceeded.

Permanent magnetic fields can also cause effects of magnetic induction and overheating in metal parts near to their source. In addition, transient magnetic fields produced by high currents at rated frequency (short circuit) or higher frequencies like in the switching of capacitive circuits, can induce high voltages in the control circuits and other closed circuits in substations.

The focus of this report is the calculation of the values, which may occur, depending on the geometry of the object under study and the values of currents and voltages involved. The object may be a complete substation or an enclosed metallic equipment. The more frequent objectives of such studies are:
a) To verify if the values of electromagnetic fields in a substation are lower than the reference levels established in references like ICNIRP “Guidelines for Limiting Exposure to Time-varying Electric and Magnetic Fields (1 Hz to 100 kHz)”. There you may find limits for human exposure to electric and magnetic fields in generation, transmission and distribution of electricity. ICNIRP means International Commission on Non‐Ionizing Radiation Protection.
b) To see if local gradients of voltage / electric field are higher than the values which could produce a dielectric discharge or corona in an energized circuit
c) To see if the magnetic field acting in a metal plate or part is sufficient to produce overheating by magnetic induction

This report intends to help the users of the software SwitchgearDesign to do validations of their simulations. The software permit to simulate:
 Temperature rise tests
 Short time current and crest tests (electro dynamical forces)
 Internal arc tests.
 Mapping of electric and magnetic fields. This ability enable the user to estimate the results of dielectric tests (impulse and applied AC voltage) as well as to solve EMC (Electromagnetic Compatibility) problems.

El objetivo de este artículo es señalar a la industria eléctrica de los países en desarrollo como... more El objetivo de este artículo es señalar a la industria eléctrica de los países en desarrollo como en América del Sur, Asia y muchos otros en el mundo, la visión del autor sobre las oportunidades con "nuevas tecnologías y procedimientos". En la Sección 2 se enumeran algunos ejemplos de las tecnologías. En la Sección 3 hay algunos parámetros que pueden ser utilizados para analizar y dar prioridad a los proyectos para invertir. En la Sección 4 enumeramos algunos enfoques para inducir a las nuevas tecnologías y procedimientos en la industria eléctrica.

The objective of this article is to signalize to the electric industry of developing countries li... more The objective of this article is to signalize to the electric industry of developing countries like in South America, Asia and many others in the World, the vision of the author about opportunities with “new technologies and procedures” to be explored locally.
In Section 2 there are some examples of the technologies. In Section 3 there are parameters which can be used to analyze and to prioritize the projects to invest, In Section 4 we list some approaches on how to induce new technologies and procedures in the electric industry.

Table 6 of IEC 61439-1: QUESTION to CERTIFIERS & TESTING LABORATORIES: -- What temperature rise limits, in bar/breaker connections, to use when approving or certifying low voltage switchgear? , 2023

With a suggestion to Cigrè • Certifiers & testing laboratories: need to use the limit values in ... more With a suggestion to Cigrè

About electric showers & technical stamdards like IEC61439-1

About damages in electric showers

Queima de chuveiros eletricos, 2023

A respeito de queima frequente de chuveiros eletricos

EC 60282-2-High-voltage fuses-Part 2: Expulsion Fuses Suggestions to SC32A for next revision, 2023

IEC 61439: The Mystery of the Temperature Rise Limits, 2019

FINDING THE OPTIMAL DESIGN USING SIMULATIONS (Aluminum x Copper) (Try to do it with real lab high power tests, 2019

ACCEPTING SIMULATIONS TO REPLACE HIGH POWER TESTS, 2019

IEC 61439connections: temperature rise of 10K aboveIEC limit= loss of life 66%, 2019

TRIAXIAL high current AIS - GIS: disclosing an idea worldwide use !,, 2019

IEC technical standards are powerful documents providing directions for specifications, tests and... more IEC technical standards are powerful documents providing directions for specifications, tests and types of equipment which will be commercialized in the Worldwide market. I learned this along my 40 years of activities in the electrical sector. Along this time, I had the satisfaction of collaborating in IEC working groups (WG) including coordinating a WG which prepared a revision of the IEC 60282-2 and, recently, a WG that prepared the new published IEC 62271-307.

Between these two moments there were advances in IEC and CIGRÈ working groups in themes involving simulations of internal arc tests, temperature rise and other types of expensive tests.

Author: Sergio Feitoza Costa sergiofeitoza@cognitor.com.br

Site : http://cognitor.com.br/en_home.htm

In this article, I present some concepts and definitions related to the design and specification ... more In this article, I present some concepts and definitions related to the design and specification of equipment for interrupting and conducting short circuit currents as well as normal currents.

IEC technical standards are powerful documents providing directions for specifications, tests and... more IEC technical standards are powerful documents providing directions for specifications, tests and types of equipment which will be commercialized in the Worldwide market. I learned this along my 40 years of activities in the electrical sector. Along this time, I had the satisfaction of collaborating in IEC working groups (WG) including coordinating a WG which prepared a revision of the IEC 60282-2 and, recently, a WG that prepared the new published IEC 62271-307.