Inductive Sensor for Measuring High Frequency Partial Discharges Within Electrical Insulation
ABSTRACT Partial discharges are not only a consequence but a symptom of insulation degradation in electrical equipment. Partial discharges are revealed outside the insulation as very narrow high-frequency pulses that were superimposed to the grid frequency high-level voltages or currents and thus are fairly hard to detect. This paper presents an application of a new inductively coupled sensor that allows these signals to be measured in an accurate inexpensive manner. The sensor model and its frequency and geometry-dependent behavior are studied to increase the probe sensitivity as much as possible. Its measuring capability in real insulation systems that were subjected to high partial discharge activity will be tested.
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ABSTRACT: Partial discharge (PD) detection is a widely extended technique for electrical insulation diagnosis. Ultrahigh-frequency detection techniques appear as a feasible alternative to traditional methods owing to their inherent advantages such as the capability to detect PDs online and to locate the piece of equipment with insulation problems in substations and cables. In this paper, four antennas are thoroughly studied by means of their theoretical and experimental behavior when measuring electromagnetic pulses radiated by PD activity. The theoretic study of the band of frequencies in which the pulse emits and the measurement of the parameters S11 are complemented with the frequency response and wavelet transform of a set of 500 time signals acquired by the antennas, and the results are analyzed in detail.IEEE Transactions on Instrumentation and Measurement 05/2013; 62(5):932-941. · 1.71 Impact Factor
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ABSTRACT: Active magnetic bearing (AMB) systems support rotating shafts without any physical contact, using electromagnetic forces. Each radial AMB uses two pairs of electromagnets at opposite sides of the rotor. This allows the rotor to float in the air gap, and the machine to operate without frictional losses. In active magnetic suspension, displacement sensors are necessary to detect the radial and axial movement of the suspended object. In a high-speed rotating machine equipped with an AMB, the rotor bending modes may be limited to the operating range. The natural frequencies of the rotor can cause instability. Thus, notch filters are a useful circuit for stabilizing the system. In addition, commercial displacement sensors are sometimes not suitable for AMB design, and cannot filter the noise caused by the natural frequencies of rotor. Hence, implementing displacement sensors based on the AMB structure is necessary to eliminate noises caused by natural frequency disturbances. The displacement sensor must be highly sensitive in the desired working range, and also exhibit a low interference noise, high stability, and low cost. In this study, we used the differential inductive sensor head and lock-in amplifier for synchronous demodulation. In addition, an active low-pass filter and a notch filter were used to eliminate disturbances, which caused by natural frequencies. As a consequence, the inductive displacement sensor achieved satisfactory linearity, high sensitivity, and disturbance elimination. This sensor can be easily produced for AMB applications. A prototype of these displacement sensors was built and tested.Sensors 07/2014; 14(7):12640-12657. · 2.05 Impact Factor
Conference Paper: A Partial Discharges acquisition and statistical analysis software[Show abstract] [Hide abstract]
ABSTRACT: Partial Discharges (PDs) are responsible for unexpected failures in power system equipment, so their measurement is a fundamental tool for electrical equipment maintenance. In order to characterize PDs activity, some statistical magnitudes are necessary. For this purpose, PDs acquisition and processing is an important tool for critical decisions related to power systems. In this paper, the main difficulties and challenges facing PDs detection, acquisition and processing are presented. Results will be compared to a commercial PDs detection system.Instrumentation and Measurement Technology Conference (I2MTC), 2012 IEEE International; 05/2012