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Development of high accuracy current transducers with microprocessed re-excitement mesh


This project proposes to identify magnetic materials, cutting methods, heat treatments, detection and control systems which will enable the construction of high accuracy and low cost AC/DC current transducers. For current detection, commercial magnetic field sensors will be evaluated (for Hall or magnetoresistive effect). Various magnetic materials of high permeability will be characterized for verification of the quality of national and imported magnetic material and of the possibility of reversing the harmful effects of the cutting process by heat treatments. It will be possible to construct a data base of the various magnetic materials. One of the innovative proposals is in the implementation of a microprocessed re-excitement mesh which will permit the use of lower cost magnetic materials, making its commercialization on the Brazilian market easier. The conclusions of this study will lead to the gradual development of more accurate current transducers The principal motivation, in the medium term, is to develop small, low cost current alligator clips which can be attached to an oscilloscope. New configurations to increase the sensitivity of the transducers and extend their frequency response will be tested. The transducers’ magnetic circuit will be optimized by means of simulation using the Finite Element Method, to optimize both the linearity and the sensitivity of the transducer. Magnetic circuits with more than one non-magnetic spacer will also be studied, aiming for the construction of bipartite current transducers. A study will also be made of methods for the linearization, calibration and compensation of the thermic variations of the transducers with the aim of implementing algorithms in microprocessors. Experiments will be carried out to verify the effect of high intensity current transitories on the calibration of the transducers. Immediately after, the possible methods of correction such as demagnetization, will be investigated. Finally, some studies on the effects of mechanical cuts on the magnetic properties of the nuclei will be investigated. (AU)