Publications

(XVI SNPTEE - NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION - 2001)
Amaury Saliba, Jaime de Oliveira, José Henrique M. Fernandes, Mário Noboru Takai, Erivelto Gomes Regueiro, Paulo Ricardo R. Liberato Silva, Reynaldo Castriota de Mello, César Augusto Luccas, Túlio Pavanello Junior
This Technical Bulletin aims at reporting the experience acquired from the installation of an additional OPGW (Optical Ground Wire) cable in ELETRONORTE’s compacted energized 500 kV Imperatriz / Presidente Dutra Transmission Line, with an extension of 385 Km. Some technical and economic aspects are initially presented in regards to the definition of comparative costs related to the implementation to an energized line switched off, as well as comments and results referring to the feasibility analyses as for the electric and mechanic/structural performance. After that, design criteria adopted and design details of the OPGW cable fastening devices are described. Then, short reports on field assembly tests, on the OPGW cable laying design process and on the results obtained are presented. To conclude, some findings that came up along the implementation of OPGW cables in compact energized TLs are listed.

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(XIV SNPTEE - NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION - 1997)
Amaury Saliba, Mário Noboru Takai, Sílvio Caldas, Paulo Ricardo R. Liberato Silva, Reynaldo Castriota de Mello, João Batista G. Ferreira da Silva, Rogério Peixoto Guimarães
This Technical Bulletin reports design and construction aspects of the single circuit, 69 kV TLs, SE Distrito Industrial - SE’s Reman / Gillette / Videolar, located in the Industrial sector in Manaus-AM, total extension of 3589 m, using constant section trussed steel structures TRUSSPOLE type (Figure 1). Initially, the basic overall characteristics that guided line design are presented, as well as the criteria adopted in the definition of the different kinds of structures used. After that, the main results obtained during the executive process are listed. To conclude, comments are made regarding the application of that design solution to low tension urban TLs.

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(XIII SNPTEE - NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION - 10/1995)
PAULO RICARDO RALO LIBERATO DA SILVA, REYNALDO CASTRIOTA DE MELLO, SÍRIO JOSÉ FERREIRA, MÁRCIA AUGUSTA DE MOURA CADETE, MAURO DIAS DE SOUZA, ROBERTO PIRES DANTAS
The bulletin reports the origin, development and results of the application of the TRUSSPOLE. It is a spatial trussed structure with a single steel foundation that is similar to a wooden or a concrete pole and that is able to associate the technical and economic advantages of the trussed structures to the ones of the massive or tubular poles. The report is on the results obtained from the design, the load tests for an initial study prototype and the construction of a 53.2 km 69 kV S.C. TL using that kind of structural solution.

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(ERLAC – CIGRE’S REGIONAL LATIN AMERICAN MEETING - 05/1993)
JOÃO BATISTA G. FERREIRA SILVA*, PAULO RICARDO R. LIBERATO DA SILVA, VILSON RENATO DA SILVA
An optimized transmission line design has to consider the strong influence of climate and landscape conditions. Thus, a line is closely connected to the area for which it was designed. Within that context, it is reasonable to think that transmission line structures (or even complete lines) are elements that cannot be standardized for the different regions under penalty of compromising targeted performance and/or economy indexes. In Brazil, however, as time went by, transmission line systems multiplied, were interconnected and lines that crossed different geographic regions appeared. Another interesting fact is that, for the same region, designs that were implemented in different periods presented quite different results due to technological progress and the experience acquired in the construction and operation of the previous systems. The result in Brazil was that TL designs for different regions in different times started to have very similar traits, especially in regards to the structures. In addition to those findings, another fact that led to the possibility of thinking about standardizing transmission lines was the way the electric power marketplace organized itself. For political, economic and social reasons, the Brazilian electric system was structured by means of groups of companies with generating and transmitting characteristics, and other companies with a strong distributor profile. Obviously, there is also a group of companies that encompass both activities. Anyway, from a certain period on, numerous sub transmission and system interconnection lines started to come up. What frequently characterizes sub transmission is the large set of short extension lines. Short extension lines usually fail to justify specific designs for economic and timeframe reasons. Consequently, small-size companies with a power distributor profile are forced to use existing and often obsolete designs for their electric power sub transmission and distribution lines. In that context, the concept of standardization emerges as an interesting idea. This bulletin intends to describe how the commission created by ELETROBRÁS through COBEI to study the standardization of 69 and 138 kV structures has been working. The commission is still working. Nevertheless, important results and conclusions have already been obtained.

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(XI SNPTEE - NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION A - 10/1991)
JOÃO FÉLIX NOLASCO, JOÃO BATISTA GUIMARÃES FERREIRA DA SILVA, LUIZ ANTÔNIO RALO LIBERATO DA SILVA, PAULO RICARDO RALO LIBERATO DA SILVA
A lot has been built in Brazil in the last twenty years in terms of transmission lines. From the north to the south of the country, many kilometers of lines were spread, crossing the most different climate and terrain regions. That set of lines built and currently in operation represents a large potential for experimental analysis, which can allow professionals working in the sector to produce more realistic designs for the lines to be built in the future. Existing lines follow up, as well as the creation of databanks from already installed climate stations, have encouraged designers to develop from the deterministic method to the probabilistic method as a basic philosophy for the design of new lines. In that context, undesirable system failures may, on the other hand, offer an extraordinary opportunity to analyze and assess what was previously being done in comparison to what is done nowadays. That is doubtless an excellent exercise to consolidate what to be done in the future. This bulletin intends to show an analysis of the accident involving 2 cable-stayed structures for 500 kV transmission lines in CEMIG’s São Simão system.

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(X SNPTEE - NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION - 10/1989)
JOÃO BATISTA GUIMARÃES FERREIRA DA SILVA, PAULO RICARDO RALO LIBERATO DA SILVA, JOÃO FÉLIX NOLASCO, LEOVERGILDO ROSETE DIAS
One of the marking trends in the current electric systems by power authorities translates into the reuse of existent transmission lines for larger capacities. The increasing difficulty to obtain new easement areas, added to scarce resources for new investment, make reuse, may it be by reinsulating or reconducting existing lines, a quite attracting solution. The renovation of old lines, till then usually based on replacing damaged or compromised elements, has to be seen from a wider perspective to increase the efficiency rate (MW/m) of the easement. The introduction of IEC/CIGRÉ statistic methods for the calculation of transmission line structure loads and the use of failure risk criteria, associated to wind return periods, came to be a valuable tool for the technical and economic evaluation of reuses. It is obvious that statistic methods themselves were not representative when providing more safety or less risk for a transmission line. However, the designer who has information on the strategic importance of a certain line for the transmission system as a whole can decide how to better reuse it, in terms of safety and reliability, by coordinating the possibility of component failure. Finally, one can say that, by adopting statistic methods, we started working with calculated risk classes and current wind values, which allows for more optimized designs and, regarding reuse studies, more opportunities to requalify the lines.

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(3º ELARC - CIGRE’S REGIONAL LATIN AMERICAN MEETING - 08/1989)
J.B.G.F.SILVA, P.R.R.LIBERATO SILVA, J.F.NOLASCO
Longitudinal imbalance loads have been a recurring study subject for the current CIGRÉ’s WG Groups - 06 – Reliability and Safety of Transmission Lines and WG - 08 - Structures for Transmission Lines. The main questions regard the way the problem is assessed, the values to be considered, the level of load uncertainty and the effects they may have on structures. Dynamic tests have been carried out in some countries, but very little could effectively been concluded so far. However, conducting cables have shown to be the safest components in a transmission line system. The occurrence of broken conductors has been low, although cascade falls have quite frequently taken place, especially in countries where high wind speeds are common. The attempt to justify those failures leads to the investigation of the structures’ longitudinal strength, which generally depends on it as a basic load for sizing, although not necessarily associated to the rupture of the conductor. A comparative analysis of the longitudinal and cross strength of certain structures reveals that there may be a big difference between them. That happens mainly for suspension towers in lines with a tension of 500 kV and above, when such structures are self-supporting. On saving purposes, those towers tend to be rectangular, with less longitudinal strength. Not correctly considering oblique and/or longitudinal wind pressures on those towers may lead to an underestimated longitudinal loading. That inaccurate evaluation, associated to the smaller structure strength to that direction, ends up by suggesting a critical and apparently unforeseen failure situation, even if the conductor is not broken. Situations such as that one may happen in Brazil where, in the recent past, structures were projected and the latest IEC recommendations were not applied. This paper intends to clarify the situation by assessing a structure model that is sensitive to the questioning above.

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(3º ELARC - CIGRE’S REGIONAL LATIN AMERICAN MEETING - 05/1989)
P.R.R.LIBERATO SILVA, J.B.G.F.SILVA, C.R.GONTIJO
A lot has been discussed recently on the use of folded plate profiles on structures for transmission lines. From the first prototypes carried out in Europe and the review of publication no. 52 of the American Society of Civil Engineering, in which the use and sizing of such profiles were also included, that subject became recurring in CICRÉ’s WG-08-Structures Work Group meetings. In philosophical terms, the issue may be addressed from a logical and rational perspective: it is the shape of each profile that is suitable for each use condition in special. However, from that logical conclusion, in a more detailed discussion on how to manufacture the structures, that apparently theoretically unlimited possibility bumps into fabrication limits and into gauge and process standardization criteria that cannot be avoided in the industrial system. Those partly antagonistic conditions start to converge to a balance position that ultimately represents the current market situation in which technically feasible and economically competitive structures start to appear. In Brazil, a lot has been asked in the last two years on the possibilities and/or advantages of developing designs for transmission line structures using those cold-formed profiles. The main questions regard the criteria to be used in sizing, the kind of profile and steel to be used, the adjustment of Brazilian manufacturers to that new product, the raw material storage issues, and the possible savings from the perspective of the Brazilian reality. The answers to those questions could only be obtained from the execution of a real design. The materialization of this pioneer project is being led by CIGRÉ Brasil’s GT-08 – Structures Work Group. That study is in its final conclusion stage. That is what follows.

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(IX SNPTEE - NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION - 10/1987)
J. B. G. F. SILVA, L.A.R.L. SILVA, R.C. MELLO - MENDES JÚNIOR INDUSTRIAL LTDA.
Overhead transmission lines in urban areas has become more and more frequent. That is due to two main reasons. First of all, transmission lines built in the past to feed substations near cities are nowadays totally incorporated to the urban landscape. The city grows and takes up the areas surrounding the line and, in some cases such as slums, even the easement. On the other side, as a result of the increasing demand, it is necessary to build sub transmission lines that interconnect incoming substations to distribution ones. For the implementation of such urban lines, the aspects related to interaction with the environment become the most relevant ones and require careful studies where visual impact, safety and compaction evaluations play an important role. Monotube steel structures proved to be excellent supports for those specific transmission lines. In what regards the system for connection to the foundation, two classical solutions have been adopted: directly setting the pole to the soil by means of concrete and the use of base plates with anchor bolts. The first solution is usually more advantageous from an economic standpoint, but it makes grading and/or the application of cambers to angle structures more difficult. It is important to say that those poles are quite flexible structures. On the other hand, direct setting makes it almost impossible to replace a damaged structure. The second solution is technically perfect, although it is expensive for the Brazilian marketplace conditions. This bulletin reports experimental tests carried out to an intermediate kind of connection to the foundation, which is as cost efficient as direct setting and as versatile as the anchor bolt solution. It is a concrete box system with water consolidated sand that is confined by means of a seal. The bulletin reports the test system and development, the results obtained from a structural and strain point of view and the final conclusions of the test.

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(IX SNPTEE – NATIONAL SEMINAR FOR ELECTRIC POWER PRODUCTION AND TRANSMISSION - 05/1987)
P. R. R. L. SILVA, J. B. G. F. SILVA
In the end of the 70’s, a lot was being discussed on the use of angle irons in the metric series for the fabrication of steel structures in Brazil. The publication of Brazilian standard no. 6109 in 1983 and the resulting offer of millimeter graduated iron angles by steelmakers intensified the discussions on the necessary adjustments regarding existing designs using inch graduated profiles, the criteria to be developed for new designs, the cost efficiency in terms of new structure weights, as well as the current availability of profiles. The conclusions and answers to these questions could only be obtained by executing a real design. Nonetheless, it was difficult to materialize that pioneer project due to commercial market conditions, raw material storage, private commercial interests and even the inertia of sectors involved. It was necessary that a power authority, Companhia Energética de Minas Gerais, through a specific bidding process, required structures to use profiles adopting the metric system. This bulletin presents the result of the first standard structure design for 138 kV single circuit TL using profiles in the metric series available in the Brazilian marketplace. Difficulties faced during the supply as well as the consequences on the calculations, design, fabrication and inspection are addressed.

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