In this paper, the design and application of a circular microstrip antenna for partial discharge detection is presented. For this purpose, the truncated ground plane technique was applied for the bandwidth enhancement. In addition, aiming at an optimized structure, the computational simulations with several combinations of the antenna dimensional parameters were performed. In order to verify whether the developed antenna met the prerequisites (bandwidth and gain) for practical application in partial discharge detection, the optimized antenna was subjected to tests in an anechoic chamber. Finally, the antenna sensitivity was compared with the IEC 60270 standard method. For this purpose, the simultaneous tests were carried out in a partial discharge generator arrangement composed of an oil cell with point-to-plane and plane-to-plane electrode configurations. The developed antenna can detect apparent charge values higher than 30 pC and has an average gain greater than 2 dB along its bandwidth. The obtained results attested to the potential of the developed antenna for the development of UHF sensors for partial discharge detection in high-voltage equipment.

A new, bio-inspired printed monopole antenna (PMA) model is applied to monitor partial discharge (PD) activity in high voltage insulating systems. An optimized sensor was obtained by designing a PMA in accordance with the characteristics of the electromagnetic signal produced by PD. An ultra-wideband (UWB) antenna was obtained by applying the truncated ground plane technique. The patch geometry was bio-inspired by that of the Inga Marginata leaf, resulting in a significant reduction in size. To verify the operating frequency and gain of the PMA, measurements were carried out in an anechoic chamber. The results show that the antenna operating bandwidth covers most of the frequency range of PD occurrence. Moreover, the antenna presented a good sensitivity (mean gain of 3.63 dBi). The antenna performance was evaluated through comparative results with the standard IEC 60270 method. For this purpose, simultaneous tests were carried out in a PD generator arrangement, composed by an oil cell with point-to-plane electrode configurations. The developed PMA can be classified as an optimized sensor for PD detection and suitable for substation application, since it is able to measure PD radiated signals with half the voltage levels obtained from the IEC method and is immune to corona discharges.

This paper discusses the application of the first peak and cumulative energy methods to calculate the time difference of arrival (TDOA) of UHF signals emitted by a partial discharge source in order to locate it. We used a 200 × 200 × 97 cm3 dimensional arrangement composed of four UHF printed monopole antennas, which was bio-inspired by the Jatropha mollissima (Pohl) Baill leaf. In addition, an oil cell composed of a pair of immersed flat-tip electrodes was used as a source of partial discharge (PD). The oil cell was positioned at four different coordinates in order to determine the efficiency of source localization based on the signals detected by the antennas and the applied methods. Finally, we evaluated the effects of the addition of noise filtering techniques and the sampling error of the measuring instrument on the localization results. Both TDOA extraction methods converged to satisfactory location results considering the dimensional arrangement evaluated, resulting in absolute errors of 7.20 cm up to 9.00 cm and 5.40 cm up to 10.96 cm, regarding the real PD position, for the cumulative energy and first peak methods, respectively.

The adaptation of dielectric windows as metamaterial superstrate over a bio-inspired Printed Monopole Antenna (PMA) was evaluated in order to improve the detection sensitivity of Ultra High Frequency (UHF) sensors designed for Partial Discharge (PD) measurement. For this purpose, rectangular and circular Split Ring Resonators (SRR) structures were designed and evaluated aiming to achieve a metamaterial superstrate that improves the characteristics of the bio-inspired PMA as the gain, bandwidth, and radiation pattern. Measurements of the PMA with metamaterial superstrate were carried out in an anechoic chamber and compared to the simulations performed. The results show that the metamaterial superstrate insertion did not impact the original operating bandwidth, covering most of the characteristic frequency range of PD activity. Moreover, this insertion resulted in a mean gain enhancement of 0.7 dBi regarding the reference PMA, resulting in an antenna with better sensitivity for PD detection (mean gain of 3.61 dBi). The PMA-metamaterial set PD detection sensitivity was evaluated through laboratory tests with a point-to-plane PD generator setup and in field with measurements from a 230 kV current transformer. The developed PMA-metamaterial set was able to detect, successfully, the activity of PD for both tests, being classified as an optimized sensor for PD detection through dielectric windows.

In this study, a new technique for circuit breaker diagnosis, based on broadband microstrip antennas, is presented. The diagnosis is based on the electromagnetic signals radiated by electric arcs in circuit breaker poles during opening operations. From each measured signal, several parameters are calculated, such as arc duration and signal energy, which are then processed by a statistical analysis routine, providing information that allows a correlation between the radiated signals and the degradation of the breaker contacts to be established. A current injection system was used in order to produce electric arcs. The technique was tested using nine contact samples, with different degradation levels. With the obtained results, it can be verified that the proposed technique is able to provide information regarding contact degradation level, arc duration, arc reignitions, and mechanical defects. The proposed technique is a simple and non-invasive solution, since the antenna can be placed far away from the equipment under evaluation. The use of antennas is a low-cost solution to circuit breaker monitoring, and since it provides a continuous monitoring system, a database containing the evolution history of contact degradation may be available.

This paper presents a technique for circuit breaker radiometric monitoring using broadband printed monopole antennas. Considering that this work represents the continuity of a previous research, the antenna has been miniaturized using a bioinspired geometry based on the Acer Macrophyllum leaf. The monitoring system consists in measuring the signal radiated by electric arcs in circuit breaker poles during its switching operations. By analyzing these signals, it is possible to evaluate, non-intrusively, the equipment electric and mechanical status, providing important information to maintenance crews regarding the need for interventions. By performing laboratory tests, it was confirmed that the developed bioinspired PMA has adequate gain values, radiation pattern and frequency range to circuit breaker monitoring applications. Moreover, field tests on a 230 kV SF6 circuit breaker were carried out, from which the proposed technique applicability was confirmed. The proposed monitoring technique can be considered a continuous and non-invasive solution, since the antennas can be placed at a safe distance from the equipment under analysis, without compromising the insulation. In the substation, the technique has the potential to detect problems of electrical and mechanical nature, since important operational parameters can be detected, such as opening time and pole synchronicity