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The eco-friendly insulating medium C6F12O has good insulation properties, and it has the prospect to be used in medium and low voltage switchgear. The compatibility between C6F12O and the sealing material commonly used in gas-insulated equipment [nitrile butadiene rubber (NBR)] needs to be studied before C6F12O could be put into practical use. In this paper, the compatibility test between NBR and C6F12O is carried out. Scanning electron microscopy and x-ray photoelectron spectroscopy are used to detect the surface morphology and element changes in NBR before and after the test. At the same time, the interaction between C6F12O and NBR is simulated based on molecular dynamics, and the solubility parameters, diffusion coefficient, and radial distribution function are calculated. The test results show that the NBR surface is damaged by C6F12O for a long time and a large number of raised cracks and F elements appear on the NBR surface. At the same time, the calculation results show that the solubility parameter of SF6 and C6F12O is 18.730 and 14.267 (J/cm3)1/2, respectively. The diffusion coefficient of C6F12O in NBR (13.500 × 10−7 cm2/s) is higher than that of SF6 (10.333 × 10−7 cm2/s), which reveals that C6F12O is easier to diffuse in NBR. Both C6F12O/NBR and SF6/NBR have hydrogen bonding force, but the interaction between C6F12O and NBR is stronger than that of SF6. These results can provide theoretical and technical reference for the material selection and design of C6F12O gas insulated equipment. [ABSTRACT FROM AUTHOR]

C6F12O has the potential to be used in gas-insulated equipment because of its excellent insulation performance and low global warming potential value. In order to study the effect of O2 on the decomposition characteristics of the C6F12O/CO2 gas mixture, power frequency breakdown experiments were conducted on a C6F12O/O2/CO2 gas mixture with different O2 mixing ratios. The decomposition products of the C6F12O gas mixture after multiple breakdowns were analyzed qualitatively and quantitatively by gas chromatography-mass spectrometry. The effects of the O2 mixing ratio, breakdown times, and effective gas production rate on the decomposition characteristics of the gas mixture were investigated. The results show that the main decomposition products are CF4, C2F6, C3F6, C3F8, C4F10, C5F12, C3F7H, and CF2O, and the addition of O2 will promote the formation of the above several decomposition products. Except for C3F6, the concentrations of other decomposition products tend to increase and then decrease with the increase in the O2 mixing ratio. The concentrations of CF4, C2F6, C3F6, and C3F8 increase with the times of breakdowns. The effective gas production rates of CF4, C2F6, and C3F8 show a trend of increasing and then decreasing in the process of adding O2 to the C6F12O/O2/CO2 gas mixture. This study provides a reference for the industrial application of the C6F12O/O2/CO2 gas mixture. [ABSTRACT FROM AUTHOR]

Dissolved gas analysis (DGA) is an effective technique to evaluate the operation status of the power transformer, and to guarantee the safe operation of the power system. Using density functional theory (DFT), we proposed the application of Pd-doped SnS2 (Pd-SnS2) monolayer as a sensing material to detect H2 and C2H2 in transformer oil. The electronic and geometric structures of Pd-doping behavior on SnS2 were also analyzed to give insight into the physicochemical property of the active surface. The adsorption configuration, density of state (DOS), frontier molecular orbital theory as well as recovery property of the adsorption systems were comprehensively studied to estimate the suitability of our proposed material for sensing application. Our calculations showed that Pd-doping exerts some deformations on the SnS2 monolayer and leads to the narrowed bandgap of such surface. Meanwhile, Pd-SnS2 monolayer has stronger adsorption performance upon C2H2 compared to H2. And the desirable interaction with C2H2 makes it possible for application of a resistance-type sensor given the good electrical response and recovery property. Our calculations are meaningful to suggest novel sensing material for application in the field of electrical engineering. [ABSTRACT FROM AUTHOR]

Theoretical analysis and experimental study were conducted to clear the partial discharge (PD) between moving charged metal particles and electrodes in insulation oil under flow state and AC condition. The rise time of the PD pulse current is tens of nanoseconds, which is not affected by velocity and voltage. The dominant frequency component of the ultra-high-frequency (UHF) signal due to charged metal particle movement is near 0.39 GHz, which is independent from velocity and voltage. The magnitudes of PD UHF signals are discontinuous and the time of occurrence of PD depends on the trajectories of charged metal particles. PD &-U-N maps clearly indicate that the phase information of the PD UHF signal on the maps is similar regardless of flow velocity and AC condition, but the voltage intensifies the PD and the flow velocity weakens the PD. The trajectories of charged metal particles in the horizontal transformer oil tract were investigated through stress analysis of charged metal particles under flow state and AC voltage. When charged metal particles move along the oil tract under the oil flow, reciprocating oscillation simultaneously occurs in the vertical direction. [ABSTRACT FROM AUTHOR]

Endogenous volatile organic compounds (VOCs) in human exhaled gases can reflect human health status and be used for clinical diagnosis and health monitoring. Acetone is the sign VOC gases of diabetes mellitus. In order to find a potential material for the detection of acetone in the application of the clinical diagnosis of diabetes mellitus. The adsorption properties, including adsorption energy, adsorption distance, charge transfer, density of states, electron localization function and electrons density difference, of acetone on BN monolayer doped with Ni were comprehensively investigated based on density functional theory. The results show that there could be chemisorption between acetone and Ni-BN monolayer and Ni-BN monolayer is probably suitable gas sensitive material for the detection of acetone in the application of diabetes mellitus monitoring and clinical diagnosis., (© 2023 IOP Publishing Ltd.)

Using first-principles theory, this paper investigates the sensing behavior of the Ru-doped PtSe 2 (Ru-PtSe 2 ) monolayer for two dominant gases, namely, H 2 and C 2 H 2 , in the transformer oil to explore its potential as a gas sensor to evaluate the operation status of the electrical transformers. Ru-doping prefers to go through the S 1 site with the largest E b of -3.71 eV. Chemisorption is identified in the H 2 and C 2 H 2 systems with E ad obtained as -0.83 and - 2.09 eV, respectively, indicating the stronger performance of the Ru-PtSe 2 monolayer upon C 2 H 2 adsorption. Meanwhile, the obvious improvement of bandgap in the C 2 H 2 system suggests the potential of Ru-PtSe 2 monolayer as a resistance-type gas sensor for C 2 H 2 detection. Moreover, the applied biaxial strains ranging at 1-5% give rise to various Q T and E g in two systems, indicating the tunable sensing response of the Ru-PtSe 2 monolayer for gas detection with modulated strains. Our calculation proposes a novel 2D sensing material for H 2 and C 2 H 2 detection, which would be beneficial to stimulate more edge-cutting research in the gas sensing field as well., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Dissolved gas analysis (DGA) in transformer oil is a workable approach to evaluate the operation status of transformers. In this paper, we proposed a Cu-doped Se-vacancy MoSe 2 (Cu-MoSe 2 ) monolayer as a promising sensing material for DGA based on first-principles theory. Three typical dissolved gases, namely, CO, C 2 H 2 , and C 2 H 4 , are the representatives to investigate the potential of the Cu-MoSe 2 monolayer upon their adsorption and sensing. Our results indicate that Cu-doping causes strong n-doping for the Se-vacancy MoSe 2 monolayer, and the Cu-MoSe 2 monolayer exhibits strong chemisorption the three gas molecules, with a calculated adsorption energy ( E ad ) of -1.25, -1.06, and -1.16 eV, respectively. Such strong interactions lead to remarkable changes in the electrical conductivity of the Cu-MoSe 2 monolayer, allowing its application as a resistance-type sensor. Besides, work function (WF) analysis shows the potential of the Cu-MoSe 2 monolayer as a promising field-effect transistor sensor as well. It is our hope that our work can stimulate more leading-edge studies of the TM-doped MoSe 2 monolayer for sensing applications in many fields., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)