Análise da imunidade de fontes de computador frente a distorções harmônicas e afundamentos de tensão

Abstract

Power supplies for electronic devices are increasingly a significant segment of total load in power systems, many of which can impact on the power quality, as well as can suffer from the disturbances present in it. Thus, many standards and recommendations been and are being developed to improve the compatibility between power systems and electronic devices, including standards that define limits for harmonic distortions and voltage sags. In this bias, this work shows some standards and recommendations pertinent of harmonic distortion, as well standards for immunity tests of devices submitted to voltage sags. In face this, experimental tests were realized with computers power supplies in controlled environment laboratory, where the basic parameters were recorded to permit detailed analysis of the power condition under different voltage excitations. Thus, in first step was checked the compatibility and immunity this equipment under test up high levels of voltage harmonic and posteriorly, this phenomena associated to voltage sag up 50% of the nominal voltage. Based on temperature, output voltage (DC), consumption current and function of power supplies, this work proves that this device can supported harmonic voltage distortion much larger than commons limits recommended (up 10 times more). Beside was certificated that the power supplies with power factor corrector (PFC) supported much more high voltage distortion levels, besides to have better performance and consumption less harmonic current than traditional design of power supplies. The results show that different waveform can affect the performance of load, principally when occur concomitantly the voltage sags, however any failure was observed for this case. From this work is feasible to think that the regulations, principally those concern the harmonic distortion, need more frequently studies and updates, considering the existence of many models of devices, in addition the better design in it. Also stay clear the necessity more investigation with different kinds and topology of power supplies for the comprehensive evaluation their performance, besides to evaluate the compatibility with the standards and recommendations, considering that the present harmonic distortion limits can be considerate much severe as to the evaluated objects.