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Abstract(s)
A presença de humidade no interior de um transformador constitui um dos principais motivos de envelhecimento prematuro e consequentemente a perda de vida útil da máquina. Embora a presença de humidade dentro de um transformador possa ter origens diversas, a sua presença limita-se ao óleo isolante e parte ativa da máquina, existindo uma sistemática migração da humidade entre os isolantes sólidos - papel, cartão, madeiras – e o fluido isolante – óleo dielétrico, em função da temperatura de trabalho. O método comum e mais habitual de redução do teor de água é através do tratamento do seu óleo isolante, contudo, a médio, longo prazo, este processo não se revela eficaz. De forma a obter melhores resultados e de uma forma mais eficiente, a eliminação da humidade deve ser feita a partir dos isolantes sólidos do transformador que pela sua natureza higroscópica são capazes de reter grandes quantidades de água impregnada. Neste enquadramento, existe um método eficaz na remoção da humidade da atmosfera interior dos transformadores, chamado de Hot Oil Spray (H.O.S.). Uma técnica que tanto pode ser usada em ambiente industrial, assim como diretamente no local de instalação do transformador. Com o objetivo de tornar este método ainda mais eficiente e fiável, quer para garantia do bom estado pós intervenção do transformador de potência, assim como um melhoramento substancial na segurança dos técnicos, será proposto na presente dissertação, um sistema automatizado capaz de controlar, monitorizar e fazer um registo fiável das grandezas envolvidas durante todo o processo de secagem. Assim sendo, a presente dissertação apresenta um sistema desenvolvido com um microcontrolador de baixo custo, Arduino, e com materiais facilmente obtidos atualmente no mercado e criar um simples sistema de monitorização e controlo capaz de: ▪ Criar uma interface gráfica do sistema a comunicar com um microcontrolador; ▪ Apresentar em tempo real as principais grandezas envolvidas no processo HOS na interface gráfica criada; ▪ Fazer o registo automático dessas grandezas num cartão de memória, numa base temporal parametrizável. Este trabalho foi baseado num processo de secagem já implementado e amplamente desenvolvido na EFACEC e em que o registo das variáveis de controlo, nomeadamente, temperaturas, pressão, vácuo e quantidade de água, são ainda nos dias de hoje registados manualmente em folhas de papel por um operador. Este sistema foi instalado e validado com sucesso numa das máquinas de secagem instalada na fábrica da EFACEC, e usado na secagem de um transformador de potência, tendo sido registados todos os valores que foram depois usados no relatório final de reparação enviado ao cliente.
The presence of moisture inside a transformer is one of the main reasons for premature aging and consequently the loss of useful life of the machine. Although the presence of moisture inside a transformer can have diverse origins, its presence is limited to the insulating oil and active part of the machine, where there’s a systematic migration of moisture between the solid insulation - paper, cardboard, wood - and the insulating fluid - dielectric oil, depending on the working temperature. The most usual and common method for reducing the water content is by treating its insulating oil, however, in the medium to long term this process is not effective. In order to obtain better results and in a more efficient way, the moisture elimination must be made from the solid insulators of the transformer which by their hygroscopic nature are able to retain large amounts of impregnated water. In this embodiment, there is an effective method of removing moisture from the inner atmosphere of the transformers, called Hot Oil Spray (H.O.S.). A technique that can be used both in an industrial environment, as well as directly on site of installation of the power transformer. With the aim of making this method even more efficient and reliable, both to guarantee the good state after intervention, as well as a substantial improvement in the safety of the technicians, it will be proposed in this dissertation an automated system capable of controlling, monitoring and to reliably record the variables involved, during the entire drying process. Thus, the present dissertation presents a system developed with a low-cost Arduino microcontroller, and with materials easily obtained today in the market to create a simple monitoring and control system capable of: ▪ Create a graphical system interface to communicate with the microcontroller; ▪ Present in real time the main variables involved in the HOS process, in a graphical interface; ▪ Automatically record these variables into a memory card on a configurable time basis. This work was based on a drying process already implemented and widely developed at EFACEC and in which the recording of the control variables, namely, temperatures, pressure, vacuum and water quantity are still, until today, manually recorded on sheets of paper by an operator. This system was successfully installed and validated on one of the EFACEC factory-installed drying machines and used for monitoring the drying of a power transformer and register all values that were then used in the final repair report sent to the customer.
The presence of moisture inside a transformer is one of the main reasons for premature aging and consequently the loss of useful life of the machine. Although the presence of moisture inside a transformer can have diverse origins, its presence is limited to the insulating oil and active part of the machine, where there’s a systematic migration of moisture between the solid insulation - paper, cardboard, wood - and the insulating fluid - dielectric oil, depending on the working temperature. The most usual and common method for reducing the water content is by treating its insulating oil, however, in the medium to long term this process is not effective. In order to obtain better results and in a more efficient way, the moisture elimination must be made from the solid insulators of the transformer which by their hygroscopic nature are able to retain large amounts of impregnated water. In this embodiment, there is an effective method of removing moisture from the inner atmosphere of the transformers, called Hot Oil Spray (H.O.S.). A technique that can be used both in an industrial environment, as well as directly on site of installation of the power transformer. With the aim of making this method even more efficient and reliable, both to guarantee the good state after intervention, as well as a substantial improvement in the safety of the technicians, it will be proposed in this dissertation an automated system capable of controlling, monitoring and to reliably record the variables involved, during the entire drying process. Thus, the present dissertation presents a system developed with a low-cost Arduino microcontroller, and with materials easily obtained today in the market to create a simple monitoring and control system capable of: ▪ Create a graphical system interface to communicate with the microcontroller; ▪ Present in real time the main variables involved in the HOS process, in a graphical interface; ▪ Automatically record these variables into a memory card on a configurable time basis. This work was based on a drying process already implemented and widely developed at EFACEC and in which the recording of the control variables, namely, temperatures, pressure, vacuum and water quantity are still, until today, manually recorded on sheets of paper by an operator. This system was successfully installed and validated on one of the EFACEC factory-installed drying machines and used for monitoring the drying of a power transformer and register all values that were then used in the final repair report sent to the customer.
Description
Keywords
HOS Arduíno Transformador