Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2017-08-02T14:32:05Z No. of bitstreams: 1 Matheus Vasconcelos Souza da Silva.pdf: 1229809 bytes, checksum: 60b25491101d92e63cc5a51a11c20976 (MD5) / Made available in DSpace on 2017-08-02T14:32:06Z (GMT). No. of bitstreams: 1 Matheus Vasconcelos Souza da Silva.pdf: 1229809 bytes, checksum: 60b25491101d92e63cc5a51a11c20976 (MD5) Previous issue date: 2017-08-01 / Nowadays, the level of business competition has substantially increased with the advent of globalization and the ease of crossing borders for countries. The technological advances and the high level of demand of markets have contributed with the new reality, demanding greater efficiency in the resource management every day. Companies all over the world face slower growth, loss of profit margin as well as internal and external competitors which no longer act as if the portion in expansion was big enough for everyone. One of the major factors for a company’s success in competitive markets is the cost competitiveness. It is critical to effectively and strategically manage internal and external factors that contribute to a competitive cost management. This research aims to contribute with the study of strategic cost management which is considered an instrument for the management of results in the Brazilian cement industries. The cement industry profile becomes even more critical when inserted in the scenario described above, of extreme competitiveness, high level of demand and considerable losses in the profit margins. It is an industry that requires large investments and it is subject to strong cost pressure. Therefore, the aim of this study is to identify whether the cement industries surveyed use the strategic. For a greater understanding and to enrich the theme, a field research has been carried out applying a questionnaire to executives who work in the finance and / or controlling area of the main Brazilian cement industries, in order to map and understand the context related to the issue of the study. This way, the question that permeates this research is: are the artifacts and the techniques from strategic cost management used as instruments of results management in cement industries? Thus, the research results illustrate that the companies surveyed use the artifacts and the techniques from GEC to manage their results, but with some room for improvement, leaving certain gaps open that could lead to better results / Nos tempos atuais, com o advento da globalização e a facilidade dos países em transpor fronteiras, elevou-se significativamente o nível de competição das empresas. O avanço tecnológico e o alto nível de exigência dos mercados contribuíram com a nova realidade, demandando a cada dia maior eficiência na gestão dos recursos. Empresas em todo o mundo enfrentam um crescimento mais lento, perda de margem de lucro, bem como concorrentes internos e externos que não agem mais como se o bolo em expansão fosse grande o bastante para todos. Um dos fatores preponderantes para o sucesso de uma empresa, em mercados competitivos, é a competitividade em custos. É fundamental gerenciar de forma efetiva e estratégica os fatores internos e externos que contribuem para uma gestão de custos competitiva. O presente trabalho busca contribuir com o estudo da gestão estratégica de custos. Esta vista como um instrumento para a gestão de resultados nas indústrias de cimento brasileiras. O perfil da indústria de cimento torna-se ainda mais crítico quando inserido no cenário mensurado acima, de extrema competitividade, elevado nível de exigência e perdas consideráveis nas margens de lucro. É uma indústria que requer grandes investimentos e está sujeita a fortes pressões dos custos. O objetivo, portanto, deste trabalho é identificar se as indústrias de cimento pesquisadas utilizam a gestão estratégica de custos como ferramenta de gestão de resultados. Para melhor compreensão e enriquecimento do tema, foi realizada uma pesquisa de campo que consiste em aplicar um questionário para executivos, que atuam na área de finanças e ou controladoria, das principais indústrias de cimento do Brasil, para mapear e entender o contexto relacionado à questão da pesquisa. Desse modo a questão que permeia esta pesquisa é: os artefatos e técnicas da gestão estratégica de custos são utilizados como instrumentos de gestão de resultados nas indústrias de cimento? Assim, o resultado da pesquisa, demonstra que as empresas pesquisadas utilizam os artefatos e técnicas das GEC para gestão de seus resultados, mas com alguns pontos de melhoria, deixando abertas algumas lacunas que poderiam propiciar melhores resultados

Em agosto de 2001 havia, no Brasil, sete fábricas de cimento com licença para o co-processamento de resíduos industriais em seus fornos, em substituição à matriz energética, e 14 outras em vias de adquiri-la. Há mais de cinco anos, a Companhia de Cimento Ribeirão Grande conta com efetiva participação de uma mistura (blend) de resíduos industriais de diferentes correntes no processo. O clínquer co-processado é hoje o componente principal do cimento portland da fábrica, o qual manteve resistências mecânicas à compressão às idades de 1, 3, 7 e 28 dias sempre acima dos limites normativos mínimos exigidos. Para atestar a imobilidade dos componentes inorgânicos incorporados ao clínquer, utilizaram-se ensaios microscópicos e análises químicas por espectrometria de absorção atômica e de raios X em clínqueres industriais não co-processados e co-processados; testes de lixiviação em cimentos de laboratório; química mineral por microssonda eletrônica e microscopia eletrônica de varredura em clínqueres dopados com Zn, V e Pb. Os resultados levaram, em linhas gerais, às seguintes considerações: - A microestrutura dos clínqueres co-processados manteve-se preservada com a introdução do blend no sistema. - As matérias-primas e o combustível fóssil respondem por boa parte dos elementos traços presentes no sistema. O blend introduz aporte extra dos elementos traços presentes na composição, enriquecendo seletivamente o clínquer co-processado. - Há, de maneira geral, compatibilidade grande dos elementos traços com o clínquer, mesmo de elementos voláteis como cádmio e mercúrio. Já cobalto e, principalmente, chumbo, são os que se mostraram menos compatíveis. - Nos clínqueres experimentais, alita incorporou preferencialmente zinco e chumbo, e belita, vanádio. - Não houve solubilização significativa de nenhum elemento de relevância ambiental dos cimentos, atestando sua retenção nos retículos cristalinos dos minerais formadores do clínquer portland. A qualidade ambiental do clínquer portland co-processado deve abranger sua propriedade de reter elementos traços em solução sólida, a manutenção da integridade das relações texturais, e a garantia da imobilidade de componentes tóxicos no produto final, através de um controle sistemático dos clínqueres e também dos cimentos. / In August 2001, in Brazil, there were seven cement plants with and an increasing number of others on the way to get the permit to co-processing, i.e. burning industrial wastes in their kilns as substitutes for fossil fuels. For over five years now the Companhia de Cimento Ribeirão Grande has counted on partial substitution of a blend of different waste streams for fossil fuels in the burning process. Co-processed clinker makes up today the main component of their Portland cement, which has shown mechanical strengths at 1, 3, 7 and 28 days permanently above standardized minimal limits. In order to assess the immobility of trace elements incorporated to the clinkers, a methodology was used which comprised carrying out microscopy and chemical analysis by atomic absorption and X-ray spectrometry of both conventional and co-processed clinkers, leaching tests on laboratory cements prepared with co-processed clinkers, mineral chemistry by electronic microprobe and scanning electronic microscopy on experimental clinkers doped with Zn, V and Pb. The results led to the following general statements: - Co-processed clinkers showed sound microstructure just like conventional clinkers. - Raw materials – limestone, clay and iron ore – and fossil fuels account a great deal for the amounts of trace elements involved in the burning process. According to its composition, the blend enriches selectively co-processed clinkers. - A general compatibility of trace elements – even highly volatile ones such as Cd and Hg – in clinker was observed. Co and especially Pb, however, were comparatively incompatible. - Alite of experimental clinkers incorporated preferentially Zn and Pb while belite incorporated V. - No elements showed any significant solubility from laboratory cements, thus attesting retention of environmentally relevant trace elements in the crystal lattice of clinker mineral phases. Co-processed Portland clinker must present environmental quality by retaining trace elements in solid solution, while being able to keep sound textural relationships, and guarantee immobility of toxic components on the final product. This should be attested through a systematic control of clinkers and also of cements.

Em agosto de 2001 havia, no Brasil, sete fábricas de cimento com licença para o co-processamento de resíduos industriais em seus fornos, em substituição à matriz energética, e 14 outras em vias de adquiri-la. Há mais de cinco anos, a Companhia de Cimento Ribeirão Grande conta com efetiva participação de uma mistura (blend) de resíduos industriais de diferentes correntes no processo. O clínquer co-processado é hoje o componente principal do cimento portland da fábrica, o qual manteve resistências mecânicas à compressão às idades de 1, 3, 7 e 28 dias sempre acima dos limites normativos mínimos exigidos. Para atestar a imobilidade dos componentes inorgânicos incorporados ao clínquer, utilizaram-se ensaios microscópicos e análises químicas por espectrometria de absorção atômica e de raios X em clínqueres industriais não co-processados e co-processados; testes de lixiviação em cimentos de laboratório; química mineral por microssonda eletrônica e microscopia eletrônica de varredura em clínqueres dopados com Zn, V e Pb. Os resultados levaram, em linhas gerais, às seguintes considerações: - A microestrutura dos clínqueres co-processados manteve-se preservada com a introdução do blend no sistema. - As matérias-primas e o combustível fóssil respondem por boa parte dos elementos traços presentes no sistema. O blend introduz aporte extra dos elementos traços presentes na composição, enriquecendo seletivamente o clínquer co-processado. - Há, de maneira geral, compatibilidade grande dos elementos traços com o clínquer, mesmo de elementos voláteis como cádmio e mercúrio. Já cobalto e, principalmente, chumbo, são os que se mostraram menos compatíveis. - Nos clínqueres experimentais, alita incorporou preferencialmente zinco e chumbo, e belita, vanádio. - Não houve solubilização significativa de nenhum elemento de relevância ambiental dos cimentos, atestando sua retenção nos retículos cristalinos dos minerais formadores do clínquer portland. A qualidade ambiental do clínquer portland co-processado deve abranger sua propriedade de reter elementos traços em solução sólida, a manutenção da integridade das relações texturais, e a garantia da imobilidade de componentes tóxicos no produto final, através de um controle sistemático dos clínqueres e também dos cimentos. / In August 2001, in Brazil, there were seven cement plants with and an increasing number of others on the way to get the permit to co-processing, i.e. burning industrial wastes in their kilns as substitutes for fossil fuels. For over five years now the Companhia de Cimento Ribeirão Grande has counted on partial substitution of a blend of different waste streams for fossil fuels in the burning process. Co-processed clinker makes up today the main component of their Portland cement, which has shown mechanical strengths at 1, 3, 7 and 28 days permanently above standardized minimal limits. In order to assess the immobility of trace elements incorporated to the clinkers, a methodology was used which comprised carrying out microscopy and chemical analysis by atomic absorption and X-ray spectrometry of both conventional and co-processed clinkers, leaching tests on laboratory cements prepared with co-processed clinkers, mineral chemistry by electronic microprobe and scanning electronic microscopy on experimental clinkers doped with Zn, V and Pb. The results led to the following general statements: - Co-processed clinkers showed sound microstructure just like conventional clinkers. - Raw materials – limestone, clay and iron ore – and fossil fuels account a great deal for the amounts of trace elements involved in the burning process. According to its composition, the blend enriches selectively co-processed clinkers. - A general compatibility of trace elements – even highly volatile ones such as Cd and Hg – in clinker was observed. Co and especially Pb, however, were comparatively incompatible. - Alite of experimental clinkers incorporated preferentially Zn and Pb while belite incorporated V. - No elements showed any significant solubility from laboratory cements, thus attesting retention of environmentally relevant trace elements in the crystal lattice of clinker mineral phases. Co-processed Portland clinker must present environmental quality by retaining trace elements in solid solution, while being able to keep sound textural relationships, and guarantee immobility of toxic components on the final product. This should be attested through a systematic control of clinkers and also of cements.

Degree Project Advanced Level - Business Administration, Linnaeus Business School at Linnaeus University, Business Process and Supply Chain Management, 4FE02E, Spring 2010.   Authors: Muhammad Rizwan ul Haque, Ahmed Nawaz Shaikh, Kamonmarn Jaenglom, Zaheer Tariq Tutor: Petra Andersson   Title: Supplier Selection Process Improvement through Six-Sigma DMAIC (A case of Lafarge Pakistan Cement Limited)   Background: Cement industry is considered to be an intensive supplier base industry. Cement manufacturing involves several types of suppliers ranging from general utilities to large plant equipments. Also, supply chain performance is significant topic in many cement organisations. The supply chain department at Lafarge Pakistan Cement Limited (LPCL) wants to inspect and improve their supplier selection process. The intended objective of this inspection is two folded. First, LPCL wants to develop a competitive supplier base out of bulk suppliers available in the market that would result in competitive advantage over its competitors. Second, they want to improve their supplier selection process so that there would be low variance and exclusion of unnecessary activities that would ultimately help in achieving the cost, quality and service enhancement objectives.   Research question: How can the existing supplier selection process at Lafarge Pakistan Cement Limited (LPCL) be improved by applying Six-Sigma DMAIC?   Methodology: This thesis is a descriptive case study and was conducted with a deductive approach. Data was collected through interviews, discussions and questionnaire. The scientific credibility of this thesis was secured by using many sources, avoidance of assumptions, studying a common process and following standardized steps of supplier selection. Conclusion: The existing process of supplier selection at LPCL was defined and mapped to understand the process characteristics and capabilities. The existing process was then analysed to identify problem areas, variations and unnecessary activities. Corrective actions were recommended to deal with problem areas and an improved supplier selection process for LPCL was suggested with process coordination and control measures. Suggestions for future research: Based on the findings of this thesis, we suggest that the further research for LPCL could be done in the area of sourcing and suppliers relationship management. Sourcing; a study could examine the sourcing policy at LPCL on purchasing practises of products. It would also be interesting to focus more on this area which leads to excellent cost reduction. Using scenario method could compare and analyse regional, national and worldwide sourcing. Supplier Relationship Management; a study could investigate supplier relationship management that leads to creating a competitive advantage for LPCL through the development of supplier performance monitoring and supplier development programme. More details could continuously move towards cost reduction, increased reliability and risk mitigation, transparency of supplier costs and quality, and enhanced efficiency of sourcing process.

Made available in DSpace on 2016-08-31T13:33:38Z (GMT). No. of bitstreams: 1 CassadraNA_DISSERT.pdf: 6154828 bytes, checksum: 2ad89fa53878aa550ba1ccac38d663ba (MD5) Previous issue date: 2013-11-28 / The Brazil is a developing nation, where economic growth is directly proportional to the consumption of the various energy sources. Thus, the trend is that demand for energy will become greater than the supply, generating a great concern about the possible lack of energy. Given this reality, government policies direct efforts to diversify the country's energy matrix. However, generate more power is not enough: there is a need, in addition to the diversification of energy sources, save on use and eliminate waste. Within this context, the industrial sector is considered the highest energy consumption, where the main source is electricity consumed. In the specific case of the cement industry, electricity accounts for the second largest source of consumption and its use is practically all for the driving force, which in turn, has a high potential for energy efficiency. Thus, in order to analyze the energy performance of a cement industry by eliminating the waste of electricity, studies have been conducted and identified points of improvements in water supply system of a cement factory with a capacity of 10 million bags of cement per year. As part of the research and energy efficiency solutions, has deployed a new automation project, which provided the achievement of improvements in the operation, control, supervision and system measurements and their electrical parameters. These improvements were made possible due to the development and application of logical control for the level of general water tank and deployment of new technologies and to control the drive of centrifugal pumps. Results showed that the activation of the centrifugal pumps through frequency inverters is more efficient than the direct drive type match and / or soft-start. How to control the level of the general reservoir, it was evident that the Control type Proportional, Integral and Derivative maintains the level of the general constant reservoir and pump operation in continuous, without increasing power consumption. Thus, it has become the most suitable for achieving energy efficiency in the factory Water Supply System / O Brasil representa uma nação em desenvolvimento, onde seu crescimento econômico é diretamente proporcional ao consumo das diversas fontes de energia. Assim, a tendência é que a demanda por energia se torne maior que a oferta, gerando uma grande preocupação com a possível falta de energia. Diante dessa realidade, as políticas governamentais direcionam esforços para diversificar a matriz energética do país. No entanto, gerar mais energia não é suficiente: existe a necessidade de, além da diversificação das fontes de energia, economizar no uso e eliminar o desperdício. Dentro deste contexto, o setor industrial é considerado o de maior consumo de energia, onde a principal fonte consumida é a eletricidade. No caso específico da indústria cimenteira, a energia elétrica corresponde a segunda maior fonte de consumo e seu uso é praticamente todo destinado à força motriz, que por sua vez, apresenta alto potencial de eficiência energética. Assim, com o objetivo de analisar o desempenho energético de uma indústria de cimento através da eliminação do desperdício de energia elétrica, foram realizados estudos e identificados pontos de melhorias no Sistema de Abastecimento de Água de uma cimenteira com capacidade de 10 milhões de sacos de cimento por ano. Como parte da pesquisa e soluções de eficiência energética, foi implantado um novo projeto de automação, que proporcionou a realização de melhorias na operação, controle, supervisão e medições do sistema e suas respectivas grandezas elétricas. Essas melhorias foram possíveis, devido ao desenvolvimento e aplicação de lógicas de controle para o nível do reservatório de água geral e implantação de novas tecnologias e controle para o acionamento das bombas centrífugas. Os resultados comprovaram que o acionamento das bombas centrífugas através de inversores de frequência é mais eficiente que os acionamentos tipo partida direta e/ou soft-start. Quanto ao controle do nível do reservatório geral, ficou evidenciado que o Controle tipo Proporcional, Integral e Derivativo mantém o nível do reservatório geral constante e a operação da bomba em regime contínuo, sem aumentar o consumo de energia elétrica. Dessa forma, o mesmo tornou-se o mais indicado para obtenção de Eficiência Energética no Sistema de Abastecimento de Água da fábrica

Resource recovery is an attractive alternative to the waste disposal problem. The chief by-product of this process, refuse derived fuel (RDF) can be co-fired in traditional coal burning facilities. The cement industry is a potential user of RDF. This study, based on a test burn done at Texas Industries Inc. in Midlothian, Texas, demonstrated the technical, environmental, and economic feasibility of using RDF fuel in a cement kiln. Technically, the cement showed no deleterious effects when RDF was substituted for coal/natural gas at 20% by Btu content. Environmentally, acid rain gases were reduced. Economically, RDF was shown to be a cost effective fuel substitute if a resource recovery facility was erected on site.

El presente trabajo de investigación tiene como objetivo analizar el desempeño financiero de las principales empresas cementeras de Perú, Chile y Colombia que cotizan en bolsa durante los años 2015 al 2019. Para ello se utilizarán la metodología de análisis Du Pont, se determinará el Valor Económico Agregado (EVA) y el riesgo de quiebra usando el modelo Z de Altman. Este trabajo de investigación tiene como propósito identificar la condición financiera de las empresas más representativas de cada país seleccionado, tomando como base sus estados financieros, donde se evaluará sus principales indicadores y aplicará modelos para determinar la salud financiera de estas empresas y como se relacionan con la realidad económica de cada una con sus respectivos países. El sector cementero en los países objeto de estudio, representa uno de los principales medidores del comportamiento económico de cada país, ya que este sector está muy relacionado con las actividades de construcción tanto privada como pública en beneficio de la población. Es un sector altamente competitivo, ya que la inversión en infraestructura siempre ha constituido un pilar en el desarrollo tanto de países emergentes como desarrollados, resultando interesante la búsqueda de mercados rentables, la optimización de procesos y estrategias de reducción de costos para obtener una mayor y mejor rentabilidad. Así también, el presente análisis busca ser una guía para inversionistas, donde se pueda determinar qué país logra brindar las mejores condiciones económicas y financieras para obtener un mejor retorno de la inversión. / The objective of this research work is to analyze the financial performance of the main cement companies in Peru, Chile and Colombia that are listed on the stock market during the years 2015 to 2019. For this, the Du Pont analysis methodology will be used, the Economic Value will be determined Aggregate (EVA) and bankruptcy risk using Altman's Z model. The purpose of this research work is to identify the financial condition of the most representative companies of each selected country, based on their financial statements, where their main indicators will be evaluated and models will be applied to determine the financial health of these companies and how they relate to the economic reality of each one with their respective countries. The cement sector in the countries under study represents one of the main measures of the economic behavior of each country, since this sector is closely related to both private and public construction activities for the benefit of the population. It is a highly competitive sector, since investment in infrastructure has always been a pillar in the development of both emerging and developed countries, making it interesting to search for profitable markets, process optimization and cost reduction strategies to obtain greater and better profitability. Also, this analysis seeks to be a guide for investors, where it can be determined which country manages to provide the best economic and financial conditions to obtain a better return on investment. / Trabajo de investigación

Under detta arbete har klinkertillverkningen hos en cementfabrik studerats. Arbetet behandlar möjligheter till förbättring, duglighet och måluppfyllelse för medelvärde och variation. En minskad variation bidrar till en jämnare kvalitet vilket i sin tur har en positiv påverkar på cementmalning, energi och kvalitet. De främsta orsakerna till variationen i klinkerns kvalitet är kvaliteten på råmjöl och aska från bränslen. Arbetet stöds av teorier som handlar om offensiv kvalitetsutveckling, förändring, ledarskap och kommunikation. Vid datainsamling och dataanalys har både kvalitativa och kvantitativa metoder tillämpats. Den insamlade materialet har hämtats från cementfabrikens egna databaser. Det slutsatser som kan dras utifrån denna studie är att klinkertillverkningsprocessen inte är statistisk jämvikt och innefattar stora mängder data som avviker från fabrikens målvärden. Askans effekt på klinkerns kalkmättnad beräknades till ca 17% av den totala variationen. Olika syn på kvalitetsbegreppet kan anses bidra till oönskad variation. / During this work, the clinker production at a cement factory has been studied. The work deals with opportunities for improvement, ability, and goal fulfillment for mean value and variation for the lime saturation factor in the clinker. A reduced variation offers a more even quality, which can have a positive impact on cement grinding, energy consumption, and quality. The main reasons for variations in the quality of the clinker are the quality of raw meal and ash from fuels. The work is supported by theories that deal with quality management, change, leadership, and communication. In data collection and data analysis, both qualitative and quantitative methods have been used. The collected material has been retrieved from the cement factory's own databases. The conclusions that can be drawn from this study are that the clinker manufacturing process is not stable and low process capability. The effect of the ash on the lime saturation of the clinker was calculated to be about 17% of the total variance. Different views on the concept of quality can also contribute to unwanted variation.

Under detta arbete studeras en av Europas mest moderna cementfabriker med kapacitet att producera runt 2,6 miljoner ton cement per år. Syftet med examensarbetet är att beskriva variationen i utfallen av råmjöl och identifiera vilka orsaker till variation som är möjliga att minska. Oavsiktliga variationer av kvalitet i råmjölet kan resultera i bristande klinkerkvalitet, som i sin tur kan medföra en betydande intäktsförlust. Arbetet utgår från teorier om offensiv kvalitetsutveckling, Six sigma, processledning och cementproduktion. En metodkombination av kvantitativa och kvalitativa metoder har tillämpats för datainsamling och dataanalys, där den kvantitativa datainsamlingen baserats på historiska data från referensorganisationen. De slutsatser som redogörs för, är att processen som studeras har möjlighet till att prestera i världsklass. Huvudsakliga bidragande orsaken är metoden för styrning där systemet saknar styrgränser som leder till överstyrning. Även materialvariation vid byten av råmaterialslimpor är en betydande orsak till variansen i råmjölet. Förutsatt att styrsystemet kopplas på för tidigt efter ett genomfört limpbyte kan effekten av ett limpbyte förvärras. Vidare tyder resultaten på att 80% av den totala variationen i råmjölets kalkmättnad skapas av limpbyten. / During this work, one of Europe's most modern cement factories is studied, with the capacity to produce around 2.6 million tons of cement per year. The purpose of the thesis is to describe the variation in the outcome of raw meal and identify which causes of variation are possible to reduce. Involuntary variations in the quality of the input raw meal can result in a lack of clinker quality, which in turn can result in a significant loss of revenue. The work is based on theories relating to Total Quality Management, process management and cement production. A method combination of quantitative and qualitative methods has been applied for data collection and data analysis, where the quantitative data collection is based on historical data gathered from the reference organization. The conclusions outlined are that the process being studied has the opportunity to perform world-class. The main contributing factor is the method for control where the system lacks control limits that lead to over compensation. Also, material variation in the case of changes of raw material piles is a significant cause of the variance in the raw meal. Provided that the control system is switched on prematurely after a raw material pile change has been carried out, the effect of the change can be worsened. Furthermore, the results indicate that 80% of the total variation in the raw meal’s lime saturation is created by raw material pile changes.

Το κεφάλαιο 1 αποτελεί εισαγωγή του αναγνώστη σε θέματα που αφορούν τα ηλεκτρικά κινητήρια συστήματα. Αρχικά πραγματοποιείται μια σύντομη ιστορική αναδρομή και περιγραφή της εξέλιξης αυτών, ενώ στη συνέχεια παρουσιάζονται οι θεματικές ενότητες που αποτελούν τη συμβολή της παρούσας διατριβής όπως ο έλεγχος των κινητήριων συστημάτων και η διάγνωση σφαλμάτων σε αυτά. Τέλος, υπογραμμίζονται οι στόχοι που ορίστηκαν και εκπληρώνονται στο πλαίσιο της εργασίας αυτής. Στο κεφάλαιο 2 γίνεται μια γενική περιγραφή των σταδίων παραγωγής τσιμέντου, παρουσιάζεται η χαρακτηριστική ροπής-στροφών του κλιβάνου με βάση τη διαθέσιμη βιβλιογραφία, αναλύονται λεπτομερώς οι τοπολογίες συστημάτων μετάδοσης που εγκαθίστανται σε κλιβάνους μικρής και μεγάλης παραγωγικής δύναμης, αναδεικνύονται οι προδιαγραφές που υφίστανται κατά την επιλογή των ηλεκτρικών κινητήριων μηχανών και τέλος τονίζονται οι απαιτήσεις του ελέγχου των κινητήριων μηχανών, έτσι όπως τίθενται από τη βιομηχανία τσιμέντου. Στο κεφάλαιο 3 περιγράφεται το μαθηματικό μοντέλο που αναπτύχθηκε και χρησιμοποιήθηκε για την προσομοίωση της λειτουργίας του συστήματος και το οποίο απαρτίζεται από τα επιμέρους μοντέλα του κλιβάνου, του συστήματος μετάδοσης της κίνησης, των τριφασικών ασύγχρονων μηχανών, των ηλεκτρονικών μετατροπέων ισχύος καθώς και του ελέγχου των κινητήριων μηχανών. Στο κεφάλαιο 4 περιγράφονται τα υποσυστήματα του υπό κλίμακα συστήματος με σκοπό την εξομοίωση, που κατασκευάστηκε στο εργαστήριο με στόχο την επαλήθευση των αποτελεσμάτων της προσομοίωσης στον ηλεκτρονικό υπολογιστή. Στο κεφάλαιο 5 γίνεται λεπτομερής αναφορά στις υφιστάμενες τεχνικές ελέγχου των τριφασικών ασύγχρονων μηχανών και στις εφαρμογές αυτών σε μονά και διπλά κινητήρια συστήματα. Στη συνέχεια πραγματοποιείται σύγκριση δύο εκ των επικρατέστερων μεθόδων ελέγχου διπλών κινητήριων συστημάτων και παρουσιάζονται ενδεχόμενες δυσλειτουργίες αυτών λαμβάνοντας υπόψη τα αποτελέσματα που προέκυψαν από την προσομοίωση του συστήματος και τα οποία πιστοποιούνται μέσω της πειραματικής διαδικασίας αλλά και της διαθέσιμης βιβλιογραφίας. Στη συνέχεια προτείνεται ένας καινοτόμος υβριδικός έλεγχος που, όπως αποδεικνύεται μέσω προσομοίωσης αλλά και πειραματικών αποτελεσμάτων, αντιμετωπίζει αποτελεσματικά τις προαναφερθείσες δυσλειτουργίες οδηγώντας σε ομαλή λειτουργία του συστήματος. Στο κεφάλαιο 6 προτείνεται, αντί των υφιστάμενων μεθόδων που περιλαμβάνουν την εγκατάσταση επιταχυνσιομέτρων, τη χρήση ακουστικών σημάτων και άλλων παρόμοιων μεθόδων, η χρήση της ηλεκτρικής κινητήριας μηχανής (τριφασικής ασύγχρονης μηχανής στην προκειμένη περίπτωση) ως αισθητήριο μέσο για τη διάγνωση μηχανολογικών σφαλμάτων στις οδοντώσεις γραναζιών. Συγκεκριμένα, εξετάζεται η επίδραση των εν λόγω σφαλμάτων στο φάσμα συχνοτήτων του φασικού ρεύματος και της ηλεκτρομαγνητικής ροπής της τριφασικής ασύγχρονης μηχανής, αποδεικνύεται η δυνατότητα διάγνωσης του σφάλματος ανιχνεύοντας την ύπαρξη πολλαπλών αρμονικών στο φάσμα τόσο του φασικού ρεύματος όσο και της ηλεκτρομαγνητικής ροπής. Στο κεφάλαιο 7 γίνεται μια εκτίμηση σε ό,τι αφορά τη συμβολή της διδακτορικής διατριβής, το κεφάλαιο 8 περιλαμβάνει μία ανά κεφάλαιο περίληψη της παρούσας διατριβής ενώ το κεφάλαιο 9 περιέχει τη διαθέσιμη βιβλιογραφία που χρησιμοποιήθηκε στην παρούσα εργασία κατά τη σειρά αναφοράς της στο κείμενο. / This thesis deals with the modeling, the control and the diagnosis of mechanical faults in a dual ac drive with common mechanical load. Chapter 1 constitutes an introduction of the reader to the electrical drive systems. Initially, a short historical retrospection of these systems is realized, while afterwards the thematic units that constitute the contributions of the present thesis, which can be summarized as the control of a dual cement kiln drive and the diagnosis of mechanical gear faults using the ac motor as a sensor, are presented. In chapter 2 the specifications and the operational characteristics of the kiln drive system are presented based on the industrial requirements and the existing references. Particularly the torque – speed characteristic load curve of the kiln, the advantages of upgrading the dc drives with ac ones, the parameters which determine the decision of installing a single or a dual transmission system and the need of uninterrupted operation of the kiln drive are underlined. In addition the step by step development of a simulating model of the under study system in the Matlab/Simulink environment is presented in chapter 3. Particularly the equations of motion for the kiln and the transmission system, the dynamic model equations of the asynchronous motor, the power electronics converters and the control strategy based on the Direct Torque Control have been incorporated in the Matlab/Simulink environment through which a theoretical investigation is realized. Moreover, the design and the development of an under scale laboratory simulating system of the kiln drive has been realized and the characteristics of the design specifications of the laboratory system are presented in chapter 4. Using the theoretical model developed in the Matlab/Simulink environment and the laboratory simulating system, a comparison of the existing control methods used for the electric drive systems (speed control and torque control) is being presented (chapter 5), focusing at specific malfunctions which can be caused by the application of these controls at a dual cement kiln drive. Taking into account these malfunctions, a novel hybrid control method is being presented whose operation is based on the application of a parallel-hybrid speed and torque control, simultaneously at both electric motors. In this way an equal load distribution can be achieved, obviating at the same the appearance of mechanical malfunctions. In chapter 6, the fault diagnosis of electromechanical drives is referenced, focusing on the identification of mechanical faults appeared in the pinion/girth gear coupling using the ac motor as a sensor. The proposed diagnostic method is based on the detection of multiples of the defective frequency at both phase current and electromagnetic torque frequency spectrum. The effectiveness of the proposed method is verified using experimental results from the laboratory simulating system, operating as a single drive. Finally, chapter 7, 8 and 9 include an estimation of the thesis contribution, a summary and the reference part respectively.