The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

Predrag Osmokrovic - One of the best experts on this subject based on the ideXlab platform.

  • Reliability of three-electrode Spark Gaps
    Plasma Devices and Operations, 2008
    Co-Authors: Predrag Osmokrovic, Nebojša Arsić, Miloš Vujisić, Koviljka Stanković, Ćemal B. Dolićanin
    Abstract:

    Two types of three-electrode gas-insulated Spark Gaps have been investigated in this paper: one with the third electrode located inside the main electrode, and the other with a separate third electrode. Three types of insulating media have been used: vacuum, SF6 and N2. Additionally, three different electrode materials have been implemented: copper, steel and tungsten. The following characteristics have been tested experimentally: the influence of insulating gas parameters on Spark gap operation, the influence of the polarity of working and trigger voltages on Spark gap operation, and the influence of the rate of rise of the trigger voltage on Spark gap operation and the degree of Spark gap irreversibility. A theoretical model of the Spark gap is presented in the paper, which provides a basis for explaining experimental results depending on specific characteristics of the Spark gap.

  • Reliability of Three-Electrode Spark Gaps for Synthetic Test Circuits
    2007 IEEE 34th International Conference on Plasma Science (ICOPS), 2007
    Co-Authors: Nebojša Arsić, Predrag Osmokrovic, Miloš Vujisić, Koviljka Stanković
    Abstract:

    Summary form only given. Development of a three-electrode Spark gap, intended for use in synthetic circuits, is considered in this paper. Two types of three-electrode gas insulated Spark Gaps have been tested: one with the third electrode located inside the main electrode, an the other with a separate third electrode. A theoretical model which enables optimal design of the Spark gap has been presented. Application of the model to both types of Spark Gaps enabled their optimal sizing. The following characteristics have been determined experimentally: the influence of insulating gas parameters on Spark gap operation, the influence of the polarity of working and trigger voltages on Spark gap operation, the influence of the trigger voltage rate of rise on Spark gap operation, and the degree of Spark gap irreversibility under conditions of exploitation. Three types of insulating gas have been used: SF6, N2, and a mixture of 60% SF6 with 40% N2 Additionally, three different electrode materials have been implemented: copper, steel and tungsten. Spark gap switching and delay times have been measured as indices of Spark gap operation. The statistical analysis of the obtained results is presented in the paper. The testing showed that N? insulated Spark Gaps have better characteristics than those insulated by SF6, which may be explained by a higher concentration of free electrons in N2 compared to the electronegative SF6. It has been found that that both the switching time and its statistical dispersion increase as the trigger pulse rate of rise becomes higher, while the delay time and its statistical dispersion decreased. Behaviour of the switching time random variable indicated the appearance of irreversible changes in the SF6 insulated Spark gap with copper electrodes. Irreversibility of the Spark gap was not affected by either the Spark gap type or the triggering mode.

  • Triggered vacuum and gas Spark Gaps
    IEEE Transactions on Power Delivery, 1996
    Co-Authors: Predrag Osmokrovic, Nebojša Arsić, Z. Lazarevic, N. Kartalovic
    Abstract:

    This paper presents a comparative analysis of the characteristics for the gas insulated three-electrode Spark Gaps and vacuum insulated three-electrode Spark Gaps. The experimental part of this paper includes the testing of Spark gap models. Two Spark gap types were studied: one having the third electrode inside the main electrode and one having a separate third electrode, both being insulated by vacuum or gas (under pressure, providing the same operating voltage as for a vacuum insulated Spark gap). Both types of Spark Gaps were theoretically sized in the optimal way. Several characteristics are determined experimentally: the influence of the gas and vacuum insulation parameters on the Spark gap functioning, the influence of the rate of rise and injected energy of the triggering pulse on the Spark gap functioning, and the degree of Spark gap erosion vs. number of operations (long-time-stability). Two types of gases were applied: SF/sub 6/ gas, N/sub 2/ gas and three vacuum (residual) pressures: 10/sup -1/ Pa, 10/sup -4/ Pa, and 10/sup -6/ Pa. Three electrode materials were used: copper, steel and tungsten. The Spark gap switching time and delay time are measured. It was found that the switching time decreases with application of pressure decrease, and the statistical dispersion of switching time raises with the pressure decrease. By comparison of results obtained for the vacuum insulated Spark gap and the SF/sub 6/ or N/sub 2/ gas insulated Spark gap, it was found that the vacuum Spark gap has a slightly shorter switching time and a significantly higher corresponding statistical dispersion.

  • numerical and experimental design of three electrode Spark gap for synthetic test circuits
    IEEE Transactions on Power Delivery, 1994
    Co-Authors: Predrag Osmokrovic, Z. Lazarevic, N Arsic, D Kusic
    Abstract:

    The development of a three-electrode Spark gap used with a synthetic circuit for circuit breaker testing is considered in this paper. Two types of three-electrode gas insulated Spark Gaps have been tested: a Spark gap with a third electrode being inside the main electrode, and a Spark gap with a separate third electrode. Both types of Spark Gaps were theoretically sized in the optimal way. Several characteristic are determined experimentally: (1) the influence of the gas insulation parameters on the Spark gap functioning, (2) the influence of the working and triggering voltages polarities on the Spark gap functioning, (3) the influence of the triggering voltage rate-of-rise on the Spark gap functioning and (4) the degree of Spark gap erosion vs number of operations. Three types of gases were applied: SF/sub 6/ gas, N/sub 2/ gas and a mixture of 60% SF/sub 6/ with 40% N/sub 2/. Also, three electrode materials were used: copper, steel and tungsten. The Spark gap switching time and delay time are measured. The statistical analysis of results is presented. >

  • Triggered three-electrode Spark Gaps
    Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference, 1
    Co-Authors: Predrag Osmokrovic, Nebojša Arsić, N. Kartalovic
    Abstract:

    Comparative analysis of the characteristics for the gas insulated three-electrode Spark Gaps and vacuum insulated three-electrode Spark Gaps is presented in this paper. The experimental part of this paper includes the testing of Spark gap models. Two Spark gap types were tested: one having the third electrode inside the main electrode and one having a separate third electrode, both being insulated by vacuum or gas (under pressure, providing the same operating voltage as for a vacuum insulated Spark gap). Both types of Spark Gaps were theoretically sized in the optimal way. Several characteristic are determined experimentally: (1) the influence of the gas and vacuum insulation parameters on the Spark gap functioning and (2) the influence of the rate of rise and injected energy of the triggering pulse on the Spark gap functioning. Two types of gases were applied: SF/sub 6/ gas, N/sub 2/ gas and three vacuum (residual) pressures: 10/sup -1/ Pa, 10/sup -4/ Pa, and 10/sup -6/ Pa. Also, three electrode materials were used: copper, steel and tungsten. The Spark gap switching time and delay time are measured.

Pan Yuan - One of the best experts on this subject based on the ideXlab platform.

  • modeling of switching delay in gas insulated trigatron Spark Gaps
    Journal of Applied Physics, 2012
    Co-Authors: Lee Li, Cai Li, Qi Xiangdong, Lin Fuchang, Pan Yuan
    Abstract:

    Based on the gas discharge theory involving distorted E-field enhancement, a physical model is proposed to estimate the switching delay for gas-insulated trigatron Spark Gaps with a trigger pin inside the main electrode. Two discovered breakdown modes, i.e., fast-breakdown mode (FBM) and slow-breakdown mode (SBM), can be unified in this model. Raether criterion can distinguish these two modes. If the main E-field and enhanced E-field near the trigger pin tip are great enough, FBM forms easily. Otherwise, if streamer development needs to rely on the second ionization process and relevant distorted E-field enhancement, the breakdown of the main gap would turn into SBM. The enhanced E-field near the trigger pin tip may affect the threshold main E-field of FBM. The distorted E-field enhancement may affect the switching delay length of SBM.

Nebojša Arsić - One of the best experts on this subject based on the ideXlab platform.

  • Reliability of three-electrode Spark Gaps
    Plasma Devices and Operations, 2008
    Co-Authors: Predrag Osmokrovic, Nebojša Arsić, Miloš Vujisić, Koviljka Stanković, Ćemal B. Dolićanin
    Abstract:

    Two types of three-electrode gas-insulated Spark Gaps have been investigated in this paper: one with the third electrode located inside the main electrode, and the other with a separate third electrode. Three types of insulating media have been used: vacuum, SF6 and N2. Additionally, three different electrode materials have been implemented: copper, steel and tungsten. The following characteristics have been tested experimentally: the influence of insulating gas parameters on Spark gap operation, the influence of the polarity of working and trigger voltages on Spark gap operation, and the influence of the rate of rise of the trigger voltage on Spark gap operation and the degree of Spark gap irreversibility. A theoretical model of the Spark gap is presented in the paper, which provides a basis for explaining experimental results depending on specific characteristics of the Spark gap.

  • Reliability of Three-Electrode Spark Gaps for Synthetic Test Circuits
    2007 IEEE 34th International Conference on Plasma Science (ICOPS), 2007
    Co-Authors: Nebojša Arsić, Predrag Osmokrovic, Miloš Vujisić, Koviljka Stanković
    Abstract:

    Summary form only given. Development of a three-electrode Spark gap, intended for use in synthetic circuits, is considered in this paper. Two types of three-electrode gas insulated Spark Gaps have been tested: one with the third electrode located inside the main electrode, an the other with a separate third electrode. A theoretical model which enables optimal design of the Spark gap has been presented. Application of the model to both types of Spark Gaps enabled their optimal sizing. The following characteristics have been determined experimentally: the influence of insulating gas parameters on Spark gap operation, the influence of the polarity of working and trigger voltages on Spark gap operation, the influence of the trigger voltage rate of rise on Spark gap operation, and the degree of Spark gap irreversibility under conditions of exploitation. Three types of insulating gas have been used: SF6, N2, and a mixture of 60% SF6 with 40% N2 Additionally, three different electrode materials have been implemented: copper, steel and tungsten. Spark gap switching and delay times have been measured as indices of Spark gap operation. The statistical analysis of the obtained results is presented in the paper. The testing showed that N? insulated Spark Gaps have better characteristics than those insulated by SF6, which may be explained by a higher concentration of free electrons in N2 compared to the electronegative SF6. It has been found that that both the switching time and its statistical dispersion increase as the trigger pulse rate of rise becomes higher, while the delay time and its statistical dispersion decreased. Behaviour of the switching time random variable indicated the appearance of irreversible changes in the SF6 insulated Spark gap with copper electrodes. Irreversibility of the Spark gap was not affected by either the Spark gap type or the triggering mode.

  • Triggered vacuum and gas Spark Gaps
    IEEE Transactions on Power Delivery, 1996
    Co-Authors: Predrag Osmokrovic, Nebojša Arsić, Z. Lazarevic, N. Kartalovic
    Abstract:

    This paper presents a comparative analysis of the characteristics for the gas insulated three-electrode Spark Gaps and vacuum insulated three-electrode Spark Gaps. The experimental part of this paper includes the testing of Spark gap models. Two Spark gap types were studied: one having the third electrode inside the main electrode and one having a separate third electrode, both being insulated by vacuum or gas (under pressure, providing the same operating voltage as for a vacuum insulated Spark gap). Both types of Spark Gaps were theoretically sized in the optimal way. Several characteristics are determined experimentally: the influence of the gas and vacuum insulation parameters on the Spark gap functioning, the influence of the rate of rise and injected energy of the triggering pulse on the Spark gap functioning, and the degree of Spark gap erosion vs. number of operations (long-time-stability). Two types of gases were applied: SF/sub 6/ gas, N/sub 2/ gas and three vacuum (residual) pressures: 10/sup -1/ Pa, 10/sup -4/ Pa, and 10/sup -6/ Pa. Three electrode materials were used: copper, steel and tungsten. The Spark gap switching time and delay time are measured. It was found that the switching time decreases with application of pressure decrease, and the statistical dispersion of switching time raises with the pressure decrease. By comparison of results obtained for the vacuum insulated Spark gap and the SF/sub 6/ or N/sub 2/ gas insulated Spark gap, it was found that the vacuum Spark gap has a slightly shorter switching time and a significantly higher corresponding statistical dispersion.

  • Triggered three-electrode Spark Gaps
    Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference, 1
    Co-Authors: Predrag Osmokrovic, Nebojša Arsić, N. Kartalovic
    Abstract:

    Comparative analysis of the characteristics for the gas insulated three-electrode Spark Gaps and vacuum insulated three-electrode Spark Gaps is presented in this paper. The experimental part of this paper includes the testing of Spark gap models. Two Spark gap types were tested: one having the third electrode inside the main electrode and one having a separate third electrode, both being insulated by vacuum or gas (under pressure, providing the same operating voltage as for a vacuum insulated Spark gap). Both types of Spark Gaps were theoretically sized in the optimal way. Several characteristic are determined experimentally: (1) the influence of the gas and vacuum insulation parameters on the Spark gap functioning and (2) the influence of the rate of rise and injected energy of the triggering pulse on the Spark gap functioning. Two types of gases were applied: SF/sub 6/ gas, N/sub 2/ gas and three vacuum (residual) pressures: 10/sup -1/ Pa, 10/sup -4/ Pa, and 10/sup -6/ Pa. Also, three electrode materials were used: copper, steel and tungsten. The Spark gap switching time and delay time are measured.

  • Numerical and experimental design of vacuum three-electrode Spark gap for synthetic test circuits
    Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference, 1
    Co-Authors: Nebojša Arsić, Predrag Osmokrovic, D. Kostic
    Abstract:

    The development of vacuum three-electrode Spark gap used with a synthetic test circuit is considered in this paper. Two types of three-electrode vacuum insulated Spark Gaps have been tested: a Spark gap with a third electrode being inside the main electrode, and a Spark gap with a separate third electrode. Both types of Spark Gaps were theoretically sized in the optimal way. Testing of the numerical design of the Spark gap was carried out experimentally. Three electrode materials were used: copper, steel and tungsten. The Spark gap switching time and delay time are measured.

Yang Gou - One of the best experts on this subject based on the ideXlab platform.

  • experimental study on surface properties of the pmma used in high power Spark Gaps
    AIP Advances, 2017
    Co-Authors: Ruoyu Han, Weidong Ding, Yunfei Liu, Yang Gou
    Abstract:

    This paper studies the surface properties of the Polymethylmethacrylate (PMMA) insulator samples used in high power Spark Gaps. Experiments on surface morphology, surface profile, surface chemical composition and surface leakage current were performed. Metal particles ejected in tangent direction of discharge spots were researched on the sample surface. Three kinds of distinct bands were found on the surface after 1500 shots: colorless and transparent sinking band, black band, and grey powdered coating band. The thickness of the coating band was tens of microns and the maximum radial erosion rate was about 10 μm/C. Surface content analysis indicated that the powdered coating was a mixture of decomposed insulator material and electrode material oxides. In addition, leakage current significantly depended on water content in the chamber and presented an U-shape curve distribution along the insulator surface, in keeping with the amount of powdered coating due to shock waves. Possible reasons of the surface pr...

  • Experimental study on surface properties of the PMMA used in high power Spark Gaps
    AIP Publishing LLC, 2017
    Co-Authors: Ruoyu Han, Weidong Ding, Yunfei Liu, Yang Gou
    Abstract:

    This paper studies the surface properties of the Polymethylmethacrylate (PMMA) insulator samples used in high power Spark Gaps. Experiments on surface morphology, surface profile, surface chemical composition and surface leakage current were performed. Metal particles ejected in tangent direction of discharge spots were researched on the sample surface. Three kinds of distinct bands were found on the surface after 1500 shots: colorless and transparent sinking band, black band, and grey powdered coating band. The thickness of the coating band was tens of microns and the maximum radial erosion rate was about 10 μm/C. Surface content analysis indicated that the powdered coating was a mixture of decomposed insulator material and electrode material oxides. In addition, leakage current significantly depended on water content in the chamber and presented an U-shape curve distribution along the insulator surface, in keeping with the amount of powdered coating due to shock waves. Possible reasons of the surface property changes were discussed. Electroconductive oxides of low valence states of Cu and W produced by the reactions between electrode materials and arc plasmas were considered to be the cause of dielectric performance degradation

Ruoyu Han - One of the best experts on this subject based on the ideXlab platform.

  • note erosion of w ni fe and w cu alloy electrodes in repetitive Spark Gaps
    Review of Scientific Instruments, 2018
    Co-Authors: Ruoyu Han, Weidong Ding, Aici Qiu, Junping Tang
    Abstract:

    A pair of W–Ni–Fe and W–Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W–Cu electrode surface to polygons while the W–Ni–Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W–Ni–Fe electrodes increased to ∼3 μm while that of W–Cu electrodes reached ∼7 μm at the end of the test. The results reveal that the W–Ni–Fe alloy has a better erosion resistance and potential to be further applied in Spark Gaps.

  • experimental study on surface properties of the pmma used in high power Spark Gaps
    AIP Advances, 2017
    Co-Authors: Ruoyu Han, Weidong Ding, Yunfei Liu, Yang Gou
    Abstract:

    This paper studies the surface properties of the Polymethylmethacrylate (PMMA) insulator samples used in high power Spark Gaps. Experiments on surface morphology, surface profile, surface chemical composition and surface leakage current were performed. Metal particles ejected in tangent direction of discharge spots were researched on the sample surface. Three kinds of distinct bands were found on the surface after 1500 shots: colorless and transparent sinking band, black band, and grey powdered coating band. The thickness of the coating band was tens of microns and the maximum radial erosion rate was about 10 μm/C. Surface content analysis indicated that the powdered coating was a mixture of decomposed insulator material and electrode material oxides. In addition, leakage current significantly depended on water content in the chamber and presented an U-shape curve distribution along the insulator surface, in keeping with the amount of powdered coating due to shock waves. Possible reasons of the surface pr...

  • Experimental study on surface properties of the PMMA used in high power Spark Gaps
    AIP Publishing LLC, 2017
    Co-Authors: Ruoyu Han, Weidong Ding, Yunfei Liu, Yang Gou
    Abstract:

    This paper studies the surface properties of the Polymethylmethacrylate (PMMA) insulator samples used in high power Spark Gaps. Experiments on surface morphology, surface profile, surface chemical composition and surface leakage current were performed. Metal particles ejected in tangent direction of discharge spots were researched on the sample surface. Three kinds of distinct bands were found on the surface after 1500 shots: colorless and transparent sinking band, black band, and grey powdered coating band. The thickness of the coating band was tens of microns and the maximum radial erosion rate was about 10 μm/C. Surface content analysis indicated that the powdered coating was a mixture of decomposed insulator material and electrode material oxides. In addition, leakage current significantly depended on water content in the chamber and presented an U-shape curve distribution along the insulator surface, in keeping with the amount of powdered coating due to shock waves. Possible reasons of the surface property changes were discussed. Electroconductive oxides of low valence states of Cu and W produced by the reactions between electrode materials and arc plasmas were considered to be the cause of dielectric performance degradation