https://iopscience.iop.org/article/10.1088/1361-6463/aab314/pdf

SF6-alternative gases for application in gas-insulated switchgear

The C5F10O gas mixture has great application prospects as a potential SF6 substitute gas. It is necessary to study the compatibility of the C5F10O gas mixture with copper and aluminum used in the electrical insulation equipment before the engineering application. In this paper, we studied the interaction of C5F10O/CO2 with copper and aluminum at various temperatures experimentally. The results show that the compatibility of copper with the C5F10O/CO2 gas mixture is obviously inferior to that of aluminum. Considering the temperature rise effect during normal operation of the equipment, it is found that the interaction between C5F10O/CO2 gas mixture and copper at 80 °C will lead to slight corrosion on the copper surface. The corrosion degree increased at the higher temperature. SEM shows that massive cubic grains will be formed on the copper surface at 150 °C–250 °C. No corrosion was observed on the aluminum surface at 150 °C ~ 250 °C, which is related to the protective effect of the oxide layer Al2O3 on the aluminum. The relevant results reveal the compatibility of the C5F10O/CO2 gas mixture with metal materials and provide an important reference for the engineering application of the C5F10O gas mixture.

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Experimental Study on Compatibility of Eco-Friendly Insulating Medium C 5 F 10 O/CO 2 Gas Mixture With Copper and Aluminum

Researchers have investigated the interruption properties of CO2 gas, including CO2 and O2 mixed gas. However, there has been no research on the passive resonance DC interrupting characteristics of CO2/O2 mixed gas. The objective of this paper is to learn the passive resonance DC interrupting properties of CO2/O2 mixed gas with superconducting fault current-limiting technology. A proposed passive resonance DCCB that includes a superconducting current-limiting module (SCLM) and a DC interrupting module (DCIM) connected in series was tested for DC voltages of 1.3, 3 and 10 kV and DC currents from 50 A to 10 kA. The experimental results show that the DCCB could successfully interrupt a 10 kA current in a 10 kV DC system. The response time of the DCCB was only 0.3 ms. After interruption, there was no overvoltage. The arcing time and the arc voltage of the SF6 gas and the CO2/O2 mixed gas were also compared experimentally. Experimental results show that CO2/O2 mixed gas may be a good substitute for the SF6 gas in passive resonance interruption. The CO2/O2 mixed gas passive resonance DCCB combined with the SCLM is an effective way to interrupt high short-circuit fault currents in medium-voltage and high-voltage DC systems.

A CO 2 /O 2 Mixed Gas DC Circuit Breaker With Superconducting Fault Current-Limiting Technology

Five-carbon perfluorinated ketone (C5F10O) has been reported as a remarkable eco-efficient replacement for SF6. To investigate its dielectric strength, thermodynamic properties and decomposition characteristics, accurate compositions of C5F10O discharge plasma are a prerequisite and can be studied by a chemical kinetic model considering non-equilibrium effects. Rate constants of C5F10O decomposition reactions are the basis for this model but have not been reported yet. Therefore, this paper is devoted to investigating the rate constants of C5F10O decomposition reactions at temperatures of 300–3500 K, relevant to electrical breakdown and arc-quenching in high-voltage electrical equipment. The rate constants and equilibrium constants as the function of temperature are computed using the transition state theory on the basis of energies and vibrational frequencies, calculated by the B3LYP/6-311G(d,p) method. The dominant reactions generating and/or consuming the species in C5F10O decomposition are also selected by contributions higher than 1%. The results in this paper show that (1) C5F10O decomposition reactions (except for R7) are endothermic and rate constants differ significantly between different reactions, mainly caused by activation energies; (2) at 1500 K and above, most rate constants fall in the region from 10−15 to 1030 cm3 mole−1 s−1 or s−1, making it so that the corresponding reactions cannot be neglected in C5F10O plasma models; (3) reactions R5, R11, R12, R14, R29, R32, R33 and R36 mainly contribute to the degradation of the insulating and arc-quenching performance of C5F10O; (4) reaction R2 plays the major role in C5F10O dissociation with the contribution more than 72.2% at temperatures of 300–3500 K. To verify the method adopted, thermodynamic properties (entropy, enthalpy and specific heat) of CF2, CF2CF2, CF3, CF–CF2 and CO are compared with those from NIST-JANAF tables and a good agreement is obtained. This work is expected to provide the input data for the calculation of non-equilibrium C5F10O discharge plasma compositions employing a chemical kinetic model.

https://iopscience.iop.org/article/10.1088/1361-6463/aae8d5/pdf

Rate constants of C5F10O decomposition reactions at temperatures of 300–3500 K

/pdf/electrical-insulation-properties-of-the-perfluoroketone-37urulpj4w.pdf

Electrical insulation properties of the perfluoroketone C5F10O

C5F10O perfluoroketone (C5 PFK) is a practically non-toxic, synthetic fluid with high dielectric strength and global warming potential below the one of CO2 that is being considered as an alternative to SF6 in certain types of electrical equipment. For high voltage applications, the low vapor pressure of C5 PFK makes it more suitable for use in indoor applications. The electric insulation and current interruption performance were investigated: Under certain conditions, mixtures of C5 PFK, oxygen and carbon dioxide can achieve electric insulation performance similar to that of SF6, while the current interruption performance measured in a model circuit breaker is somewhat below that of SF6.

Mixtures of CO2 and C5F10O perfluoroketone for high voltage applications

An HVDC circuit breaker unit (1) with an interrupter branch (2) extending between a first node (3) and a second node (4) comprising a vacuum interrupter (5) connected to the first node (3), and a gas interrupter (6) connected to the second node (4) of the circuit breaker unit. The vacuum interrupter (5) is connected to the circuit breaker unit (1) at a third node (7) such that the gas interrupter (6) is electrically connected in series to the vacuum interrupter (5). A first movable contact member (11) of the vacuum interrupter (5) and a second movable contact member (12) of the gas interrupter (6) are operatable by at least one Thomson coil drive. An arrestor branch (8) comprising a first non-linear resistor (9)is connected to the first node (3) and the second node (4).

High voltage dc circuit breaker unit

Gas-insulated high voltage puffer breaker (1) comprising a puffer unit (3) with a movable piston (4) running in a puffer cylinder (5) and delimiting a puffer volume (6) A piston (4) and a first contact member (2) are attached to a piston stem (9) An electric arc is extinguishable in an arcing zone (13) when the first contact member (2) moves from a first position to a second position The puffer volume (6) is fluidly connected to a gas nozzle (12) by a gas channel (14) such that the puffer volume (6) comprises the gas channel (14) as well as a portion (15) of the puffer cylinder (5) The gas channel (14) is provided radially outside of the puffer (5) cylinder between a puffer cylinder wall (17) delimiting the puffer cylinder (5) and a wall structure (18) of the puffer unit (3)

High voltage puffer breaker and a circuit breaker unit comprising such a puffer breaker

Voltage–current characteristics of free burning arcs in SF6 and air have been known for decades. As the demand for an SF6-free solution is increasing, there is an accompanying need to determine arc parameters in the alternative gases. An unblown arc experiment has been established to determine the voltage–current characteristics of SF6 alternative gases, which have not yet been thoroughly studied. In this experiment, free burning arc measurements were performed in a number of gases under consideration of SF6 alternatives, including CO2 and mixtures of CO2/O2 with and without C4F7N or C5F10O additives at the concentrations of up to 10 %. Measurements were also performed in air and SF6 for comparison. Arc voltage was measured in each gas at pressures ranging from 1- to 5-bar absolute, and electrode separations ranging from 20 to $95 \mathrm {~mm}$ . Voltage–current characteristic measurements for air and SF6 show good agreement with previously published results. A linear relationship of the arc voltage to the arc length is shown as well as the fourth root dependence of the arc voltage on the gas pressure. It was shown that neither the O2 nor the fluorinated additives to CO2 have any significant influence on the voltage–current characteristic. The minimum arc voltage in all measured gases was slightly higher than in SF6, but the arc in SF6 was the least stable and had the highest elongations resulting in high-voltage peaks. The arc voltage in air had a similar minimum value to the CO2-based gases, but the arc was much more stable, resulting in lower effective voltage, especially at low currents.

Voltage–Current Characteristic of Free Burning Arcs in SF₆ Alternative Gas Mixtures

The present invention relates to a dielectric insulation or arc-extinction fluid comprising or essentially consisting of: a) a fluorinated organic compound FOC1 as a first fluid component A in mixture with b) a second fluid component B different from the said first fluid component A. According to the invention, said first fluid component A is a hydrochlorofluoroolefin.

Philipp Simka

Papers

Mixtures of CO2 and C5F10O perfluoroketone for high voltage applications

High voltage dc circuit breaker unit

High voltage puffer breaker and a circuit breaker unit comprising such a puffer breaker

Voltage–Current Characteristic of Free Burning Arcs in SF₆ Alternative Gas Mixtures

Dielectric insulation or arc-extinction fluid