Resumo:
The electric power sector plays an essential role in society. As the power transformer, the equipment that represents the greatest strategic importance and the greatest investment. The failure of a power transformer causes huge financial losses, paralyzing even an entire city, leaving the population without access to the basic needs and inoperative plants. For this reason, power transformers must be in unceasing functioning monitoring.
The ageing of power transformers is directly related to the degradation of the insulating system mainly composed of paper and insulating oil. Although the both materials ageing, one of the major concerns of the companies is related to the insulating paper, when the insulating oil is degraded, it is possible to regenerate or replace it, while the paper in degradation implies long stops of the equipment and high costs for exchanging the insulating paper. For this reason, investment in high-performance insulating paper has been the best option for extending the useful life of power transformers.
In this postgraduate work, a dielectric coating on the surface of the insulating paper using a material based on SiO2 (silicon dioxide) was added to the insulating paper Nomex® type E56, manufactured by the company DuPont, improving the hydrophobicide of Nomex® type E56 paper, to improve the dielectric and mechanical properties, as well as its resistance to thermal and electrical degradation.
The obtained results were not satisfactory and, aiming to obtaining a Nomex® E56 paper covering with better performance characteristics, the studies continued with the precursor solution with polyvinylidene fluoride (PVDF) alteration.
After chemical, physical, dielectric and mechanical tests, it was demonstrated that the results were obtained right after the dielectric paper covering was utilized in power transformers.
