Exploring the Decomposition Products of 1,3,3,3Tetrafluoropropene and Perfluoro-(3-methylbutan-2-one) Gas Mixtures in Medium -Voltage Electrical Switchgear as Alternatives to SF6

In this work, binary and ternary gas mixtures of 1,3,3,3-tetrafluoropropene, HF0234ze(E), and perfluoro-(3-methylbutan-2-one), CF3C(0)CF(CF3)2 with CO, and synthetic air, are presented as alternatives to SF6 in medium-voltage electrical equipment. They were used in four medium voltage switchgear cubicles replacing SF6 gas, and after a period of time, under permanent 30 kV AC voltage, gas mixture samples were extracted and analyzed on the same day using a validated methodology' based on gas chromatography (GC) coupled to mass spectrometry (MS) and thermal conductivity (TCD). CF4 (tetrafluoromethane), C2F6 (hexafluoroethane), C,F6 (hexafluoropropylene), C3FIF7 (1,1,1,2,2,3,3-heptafluoropropane), CHF, (difluoromethane), and the cis and trans-C3H2F4 (1,3,3,3 tetrafluoropropene) have been identified as decomposition products in these gas mixtures. In addition, a quantity of water has been observed, as well as CO in one of the cubicles. The most abundant decomposition products identified in gas mixture samples (C3HF7 and C3F6) together with water and CO content have been quantified using commercial gas mixture reference standards. The toxicity and global warming of the analyzed compounds are evaluated to determine the most adequate gas mixture among those studied as a candidate to substitute SF6.This work was supported the Basque Country Government (project Elkartek KK-2017/00090

Thermal and Non-Thermal Plasma for Destruction of Pollutants

Wastewater remediation has become a global concern; thus, thedevelopment of innovative advanced oxidation processes (AOPs)for wastewater treatment is still a major challenge. Advanced oxidationprocesses (AOPs) are innovative tools that involve an introductionof energy (e.g., chemical, electrical and radiative) intothe reaction zone to generate highly reactive species, especiallyhydroxyl radicals (HO?). In this sense, plasma technology is includedamong AOPs and considered as a promising remediationtechnology for water remediation. Developed since 1987, thetechnique is environmentally friendly, simple and effective for decomposingtoxic organic compounds in raw water or wastewater. In view of these facts, applications of atmospheric pressureelectrical plasma technologies for water treatment attract the increasinginterest and emerge as technological opportunities for theplasma community.Fil: Litter, Marta Irene. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentin

Inhibition effect of solid products and DC breakdown characteristics of the HFO1234Ze(E)-N2-O2 ternary gas mixture

HFO1234ze(E) is an environmentally friendly SF6 substitute gas with prominent application potential. To suppress the generation of the HFO1234ze(E) solid decomposition products, which may cause great hazards to the gas–solid insulation strength, a gas mixing scheme screening method based on the reactive force field (ReaxFF) molecular dynamics (MD) simulation was innovatively proposed. The simulation results show that the inhibitory effect of O2 on the formation of HFO1234ze(E) solid products is better than those of CO2 and CF4. Further study shows that when O2 accounts for 3.33% of the gas mixture, the solid precipitate content is reduced by 48%. The experimental study shows that an O2 content of 3.33% can inhibit the generation of solid products by more than 50%. Besides, compared with HFO1234ze(E)-N2, the DC breakdown voltage of HFO1234ze(E)-N2-O2 is slightly increased, and the breakdown voltage dispersion degree and continuous breakdown voltage drop rate are decreased. This work gives a feasible solution for the suppression of HFO1234ze(E) solid decomposition products and provides an efficient method for solving similar problems of environmentally friendly insulating gas in C/F/O/N systems

Surface Treatments to Reduce Leakage Current in Homojunction In0:53Ga0:47As PIN Diodes for TFET Applications

In the field of low power electronics, Tunnel field-effect transistors (TFETs) are gaining momentum due to aggressive voltage scaling. To enable scaling of power supply while maintaining a high Ion, a steep subthreshold slope and low I0 are required. A TFET operates as a gated PIN diode under reverse bias with the intrinsic region as the channel. This study focuses on minimizing I0 in a III-V homojunction PIN diode. I0 or leakage current is the current owing in a PIN diode under reverse bias, that forms the o-state current (Vgate = 0 V) in a TFET. Various surface treatment combinations were performed to study surface leakage, of which, BCB and HCl were the most eective passivation and clean, respectively. For the first time, in this study, electrical characterization of sub-micron PIN diodes was performed

AC volume breakdown and surface flashover of a 4% NovecTM 4710/96% CO2 gas mixture compared to CO2 in highly nonhomogeneous fields

AC pre-discharge currents, breakdown, and flashover voltage measurements are reported in a 10 mm needle-plane arrangement in a 4% NovecTM 4710/96% CO2 gas mixture and compared with CO2 for pressures up to 8.8 bar abs. Flashover measurements were performed on different solid dielectrics (Al2O3_filled epoxy resins, PTFE (Polytetrafluoroethylene) and PE (polyethylene)) for different roughness surface finishes. The effect of fixed conducting needles at various positions on electrical strength is reported. A strong nonlinear behaviour as function of gas pressure was observed for all the studied parameters (gas, needle position, solid insulator, insulator roughness). The non-linear behaviour is attributed to the inception and quenching of glow corona, in the interval between inception and breakdown or flashover voltages. It is found that a 4% concentration of NovecTM 4710 in CO2 has a breakdown/flashover voltage ≈ 1.14 higher than CO2. The glow corona-induced stabilization effect is seen for pressures between 2 and 5 bar abs for all the studied parameters. The peak flashover voltage and its associated pressure of the different insulators are strongly dependent on surface roughness. At 8.8 bar abs, the flashover voltage level obtained with various materials was ordered as follows: PTFE > PE-UHMW > Epoxy > HDPE(High-density polyethylene)