Papers by Author: J.C. Santos

Abstract: The objective of this work was to produce red ceramic glazed with dimension stone waste. The clay and residue were characterized for crystalline phases (XRD), chemical analysis (XRF) and particle size. Additives were added to the residue in order to reduce the melting point of 1280 oC to 980 °C, because 1100 °C is the temperature typically used in industrial sintering of coating ceramics. It was studied different compositions of glaze and analyzed its viscosity. The engobe and the glaze were applied on the red ceramic, previously pressed with 100x100x5 mm³ size, and sintered at 1100 oC for 1 h, in order to obtain the ceramic coating. These ceramics were analyzed for abrasion resistance, water absorption and chemical attack, according to NBR 13.818/1997, being classified as PEI 1, indicate for use in residential bathrooms and bedrooms without doors outwards, showing the potential use of dimension stone waste for flooring ceramics, mitigating environmental impacts in mineral industry.

Abstract: Our aim is to show some impacts on the differential protection of power transformers when using Non-Conventional Instrument Transformers associated with the IEC 61850-9-2 process bus. Described herein are a model for simulating the samples in the process bus, a proposed algorithm for differential protection of power transformers adapted from conventional differential relays so that it works according to the IEC 61850-9-2 standard, and a response analysis of the protection algorithm with the loss of the time synchronization signal in the process bus. Suggestions on parameters to be followed for safer operation of the process bus in these circumstances are also offered.