Sistema de aquisição de dados para monitoramento de transformadores de distribuição.

Abstract

In this work, a data acquisition system for three-phase transformers distribution is presented. The system is able to measure and analyze waveforms of voltage and current, calculate its RMS values, harmonic values, total harmonic distortion, demanded power, power factor and temperature in the transformer housing. The measured data is transferred via wireless network with ZigBee protocol, to a personal computer, where na software interface was developed to center and present the data in the form of numerical and graphical presentations. The data acquisition system uses a microcontroller PIC18LF4520, a three-phase power meter ADE7880 and a wireless transceiver XBee-Pro. The data is measured and sent continuously, allowing a user, in distance, monitor the electrical variables inherent in the distribution transformer, and can thus evaluate the energy characteristics provided by the equipment. The system was characterized, developed and validated in the laboratory with linear and nonlinear loads, and then installed in a transformer located at Laboratório de Alta Tensão. The developed system has presented percentage deviations relative to the Electric Power Quality Analyzer, higher in measurements of current signals of nonlinear loads and lower in measurements of voltage signals.The system can be used not only to monitor distribution transformers, but also any other equipment that fits in their limits of maximum current and voltages.