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F.A. Muñoz Muñoz
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5 records found
1
Conference paper
(2026)
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M.S. Saleem, F.A. Muñoz Muñoz, Dennis van der Born, A.G.A. Lathouwers, P.T.M. Vaessen
Due to environmental concerns, there is a growing trend toward sustainable insulation gas alternatives for $\mathbf{S F}_{6}$. Understanding the dielectric behavior of these alternative gases is essential for ensuring component and system reliability. Normalized differential (NoDi) plots were employed to study the partial discharge (PD) performance of technical air, pure $\mathbf{C O}_{2}$, and $\mathbf{C O}_{2} / \mathbf{O}_{2}$ mixtures. The inception voltage, repetition rate, and mean charge were analyzed to evaluate the partial discharge behaviour. A high-frequency current transformer (HFCT)-based measurement system is used to detect partial discharge (PD) pulses. This setup enables detailed time-domain acquisition of fast-rising PD pulses by employing an HFCT installed around the connection to the ground electrode. With this setup, the PD characteristics of high-voltage side protrusions were examined for different gases; technical air, pure $\mathbf{C O}_{2}$, and $\mathbf{C O}_{2} / \mathbf{O}_{2}$ mixtures with different pressures. The results show that all gases have comparable inception voltages. The $\mathbf{C O}_{\mathbf{2}} / \mathbf{O}_{\mathbf{2}}(\mathbf{7 0 \%} / \mathbf{3 0 \%})$ investigated in this paper exhibits the lowest discharge magnitude among all the gas mixtures studied. For this reason, it seems to be a promising mixture for an $\mathbf{S F}_{6}$-free insulation option.
...
Due to environmental concerns, there is a growing trend toward sustainable insulation gas alternatives for $\mathbf{S F}_{6}$. Understanding the dielectric behavior of these alternative gases is essential for ensuring component and system reliability. Normalized differential (NoDi) plots were employed to study the partial discharge (PD) performance of technical air, pure $\mathbf{C O}_{2}$, and $\mathbf{C O}_{2} / \mathbf{O}_{2}$ mixtures. The inception voltage, repetition rate, and mean charge were analyzed to evaluate the partial discharge behaviour. A high-frequency current transformer (HFCT)-based measurement system is used to detect partial discharge (PD) pulses. This setup enables detailed time-domain acquisition of fast-rising PD pulses by employing an HFCT installed around the connection to the ground electrode. With this setup, the PD characteristics of high-voltage side protrusions were examined for different gases; technical air, pure $\mathbf{C O}_{2}$, and $\mathbf{C O}_{2} / \mathbf{O}_{2}$ mixtures with different pressures. The results show that all gases have comparable inception voltages. The $\mathbf{C O}_{\mathbf{2}} / \mathbf{O}_{\mathbf{2}}(\mathbf{7 0 \%} / \mathbf{3 0 \%})$ investigated in this paper exhibits the lowest discharge magnitude among all the gas mixtures studied. For this reason, it seems to be a promising mixture for an $\mathbf{S F}_{6}$-free insulation option.
Conference paper
(2026)
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L. Bolzonella, F.A. Muñoz Muñoz, Mohamed Agazar, Johann Meisner, M. Ghaffarian Niasar
Very Fast Transients (VFTs) are high-frequency, steep-fronted voltage impulses that occur in high-voltage power systems and advanced power electronic applications. VFTs possess short rise times down to a few nanoseconds and peak voltages up to hundred kilovolts, they can cause potential degradation and failure in system insulation, equipment, and measurement technology. High frequency ranges (above 300 MHz) and amplitudes render accurate measurements of voltage transients challenging, and existing literature lacks in standardization and traceability. VTT Technical Research Center of Finland developed a resistive divider designed for capturing puncture test waveforms with amplitudes of 600 kV and 5 ns rise time. In this paper, the divider is evaluated for rise time measurements of pulsed waveforms with rise times below 5 ns, identifying the effect of measurement environment and parasitics, and optimizing the design to improve the performance. After the analysis, the modified design is capable of measuring pulses with rise times as fast as 1 ns with an estimated voltage rating of 300 kV. Thermal management considerations are also performed to ensure the resistive components can withstand the pulsed energy losses.
...
Very Fast Transients (VFTs) are high-frequency, steep-fronted voltage impulses that occur in high-voltage power systems and advanced power electronic applications. VFTs possess short rise times down to a few nanoseconds and peak voltages up to hundred kilovolts, they can cause potential degradation and failure in system insulation, equipment, and measurement technology. High frequency ranges (above 300 MHz) and amplitudes render accurate measurements of voltage transients challenging, and existing literature lacks in standardization and traceability. VTT Technical Research Center of Finland developed a resistive divider designed for capturing puncture test waveforms with amplitudes of 600 kV and 5 ns rise time. In this paper, the divider is evaluated for rise time measurements of pulsed waveforms with rise times below 5 ns, identifying the effect of measurement environment and parasitics, and optimizing the design to improve the performance. After the analysis, the modified design is capable of measuring pulses with rise times as fast as 1 ns with an estimated voltage rating of 300 kV. Thermal management considerations are also performed to ensure the resistive components can withstand the pulsed energy losses.
Conference paper
(2026)
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F.A. Muñoz Muñoz, Dennis van der Born, M.S. Saleem, Maximilian Vogl, Elias Speinle, Maximilian Millisterfer
This study presents a comparative evaluation of electrical and optical partial discharge measurement systems in alternative insulating gases, namely CO2 and compressed air, within a metal-enclosed compartment. Five representative defect types were investigated over a range of pressures and voltage levels. The results show that the optical method consistently exhibits higher sensitivity and provides more comprehensive phaseresolved information, particularly at low discharge intensities where the electrical method frequently fails to detect PD activity.
...
This study presents a comparative evaluation of electrical and optical partial discharge measurement systems in alternative insulating gases, namely CO2 and compressed air, within a metal-enclosed compartment. Five representative defect types were investigated over a range of pressures and voltage levels. The results show that the optical method consistently exhibits higher sensitivity and provides more comprehensive phaseresolved information, particularly at low discharge intensities where the electrical method frequently fails to detect PD activity.
Journal article
(2025)
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M. Rom, Helko E. van den Brom, E. Houtzager, R. van Leeuwen, D. van der Born, G. Rietveld, F. Muñoz
Accurate and reliable characterization of current transformer (CT) performance is essential for maintaining grid stability and power quality in modern electrical networks. CT measurements are key to effective monitoring of harmonic distortions, supporting regulatory compliance and ensuring the safe operation of the grid. This paper addresses a method for the characterization of CTs across an extended frequency range from 50 Hz up to 150 kHz, driven by increasing power quality issues introduced by renewable energy installations and non-linear loads. Traditional CT calibration approaches involve measurement setups that offer ppm-level uncertainty but are complex to operate and limited in practical frequency range. To simplify and expand calibration capabilities, a calibration system employing a sampling ammeter (power analyzer) was developed, enabling the direct measurement of CT secondary currents of an unknown CT and a reference CT without any further auxiliary equipment. The resulting expanded magnitude ratio uncertainties for the wideband CT calibration system are 10 ppm (k=2) up to 10 kHz and less than 120 ppm from 10 kHz to 150 kHz; these uncertainties do not include the uncertainty of the reference CT. Additionally, the operational conditions and setup design choices, such as instrument warm-up duration, grounding methods, measurement shunt selection, and cable type, were evaluated for their impact on measurement uncertainty and repeatability. The results highlight the significance of minimizing parasitic impedances at higher frequencies and maintaining consistent testing conditions. The developed calibration setup provides a robust foundation for future standardization efforts and practical guidance to characterize CT performance in the increasingly important supraharmonic frequency range.
...
Accurate and reliable characterization of current transformer (CT) performance is essential for maintaining grid stability and power quality in modern electrical networks. CT measurements are key to effective monitoring of harmonic distortions, supporting regulatory compliance and ensuring the safe operation of the grid. This paper addresses a method for the characterization of CTs across an extended frequency range from 50 Hz up to 150 kHz, driven by increasing power quality issues introduced by renewable energy installations and non-linear loads. Traditional CT calibration approaches involve measurement setups that offer ppm-level uncertainty but are complex to operate and limited in practical frequency range. To simplify and expand calibration capabilities, a calibration system employing a sampling ammeter (power analyzer) was developed, enabling the direct measurement of CT secondary currents of an unknown CT and a reference CT without any further auxiliary equipment. The resulting expanded magnitude ratio uncertainties for the wideband CT calibration system are 10 ppm (k=2) up to 10 kHz and less than 120 ppm from 10 kHz to 150 kHz; these uncertainties do not include the uncertainty of the reference CT. Additionally, the operational conditions and setup design choices, such as instrument warm-up duration, grounding methods, measurement shunt selection, and cable type, were evaluated for their impact on measurement uncertainty and repeatability. The results highlight the significance of minimizing parasitic impedances at higher frequencies and maintaining consistent testing conditions. The developed calibration setup provides a robust foundation for future standardization efforts and practical guidance to characterize CT performance in the increasingly important supraharmonic frequency range.
Conference paper
(2025)
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T. Plantfeber, M.S. Saleem, F. M. Muñoz, D. van der Born, A. Lathouwers, P. Vaessen
As the world moves towards S F6-free insulation technologies, understanding the dielectric behaviour of alternative gas mixtures is becoming increasingly important. Detailed characterization of partial discharge (PD) behaviour within conventional measurement circuits is constrained by distortion of the fast transient signal, limiting the effective measurement bandwidth. This study presents a novel measurement circuit that omits the traditional coupling capacitor and instead leverages the inherent capacitance of the gas-insulated structure to establish a more compact and sensitive detection path. The improved setup enables detailed time-domain acquisition of fast-rising PD pulses using a high-frequency current transformer (HFCT). Using this system, the corona discharge characteristics of a CO2 / O2(7 0 % / 3 0 %) gas mixture are experimentally investigated at pressures of 0.2,0.3 and 0.4 MPa. Phase-resolved PD patterns are analysed to assess the influence of gas pressure on PD inception voltage, charge magnitude, and pulse repetition behaviour.
...
As the world moves towards S F6-free insulation technologies, understanding the dielectric behaviour of alternative gas mixtures is becoming increasingly important. Detailed characterization of partial discharge (PD) behaviour within conventional measurement circuits is constrained by distortion of the fast transient signal, limiting the effective measurement bandwidth. This study presents a novel measurement circuit that omits the traditional coupling capacitor and instead leverages the inherent capacitance of the gas-insulated structure to establish a more compact and sensitive detection path. The improved setup enables detailed time-domain acquisition of fast-rising PD pulses using a high-frequency current transformer (HFCT). Using this system, the corona discharge characteristics of a CO2 / O2(7 0 % / 3 0 %) gas mixture are experimentally investigated at pressures of 0.2,0.3 and 0.4 MPa. Phase-resolved PD patterns are analysed to assess the influence of gas pressure on PD inception voltage, charge magnitude, and pulse repetition behaviour.