Thomson scattering diagnostics of SF 6 gas-blasted arcs confined by a nozzle under free-recovery conditions

Tomita²,

Inada

et al. 2017

PPT

Abstract. This paper briefly introduce research work examples of non-equilibrium studies in switching arcs. In understanding arc behavior, one often assumes local thermodynamic equilibrium (LTE) condition in the arc plasma. However, actual arc plasmas are not completely and not always in LTE state because of strong temperature change temporally and spatially, and high electric field application etc. Recently, we have a collaboration work in numerical simulations and experimental approaches for decaying arcs without LTE assumption. First, our numerical model is presented for decaying arcs without chemical equilibrium assumption. Secondly, two experimental methods are introduced for measuring electron density in decaying arcs without LTE assumption: Laser Thomson Scattering method and the Schack-Hartmann method. Finally, comparison results is shown between the LTE simulation, the chemically non-equilibrium simulation, and the above experimental measurements.

Section: Laser Thomson Scattering Methodsmentioning

confidence: 99%

Section: Laser Thomson Scattering Methodsmentioning

confidence: 99%

Section: Experimental Approaches: Electron Density Measurement Withoumentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Non-equilibrium Studies in Switching Arc Plasmas in Japan

Tomita²,

Inada

et al. 2017

PPT

“…For the experiment, we use a DC current source and a power semiconductor, insulated gate bi-polar transistor (IGBT) to control current and voltage for the arc plasmas with an accuracy in time. Previously, the arc behavior and electron density in the arcs in the gas flow were measured in detail by using a laser Thomson scattering (LTS) under free recovery condition of the arcs [1], [2]. In addition to these, the arc behavior has been observed using a high speed video camera for visible light from the arc.…”

mentioning

confidence: 99%

Evaluation on current interruption ability of CO2 and SF6 using current and voltage application highly controlled by power semiconductors

Nakano

Murai

2015 3rd International Conference on Electric Power Equipment – Switching Technology (ICEPE-ST)

et al. 2015

Self Cite

Abstract-This paper reports a new simple test technique to evaluate current interruption ability of arc quenching gases. In the test, current and voltage applied to the arc was controlled using a insulated gate bipolar transistor (IGBT). Switching the IGBT enables us to produce free recovery conditions for a fundamental arc decay in nozzles. In addition to this, a voltage was intentionally applied to the free recovery arcs between the electrodes by switching-off IGBT again at the specified delay time t d . This applied voltage is called quasi transient recovery voltage (quasi-TRV). We can evaluate successful interruption or interruption failure by measuring the current between the electrodes after quasi-TRV application. We compared the interruption ability of SF6 and CO2 through this developed technique. The experimental results show that a residual arc in SF6 gas flow decays four times more rapidly than that in CO2 gas flow. Influence of observation holes in the nozzles used in the experiments was also investigated, showing less influence of observation on the arc behavior.

Numerical thermofluid simulation of a decaying arc behavior in CO₂/O₂/C₅F₁₀O (C5‐PFK) considering more than nona‐atomic molecules

Demura

IEEJ Transactions Elec Engng

Uesugi

et al. 2019

Self Cite

The present article describes numerical thermofluid simulation results on decaying arc behavior in 80%CO 2 + 10%O 2 + 10%C 5 F 10 O (C5-PFK) gas considering molecules constituted with more than 9 atoms in a nozzle space on the assumption of local thermodynamic equilibrium (LTE) condition. The gas mixture 80%CO 2 + 10%O 2 + 10%C 5 F 10 O (C5-PFK) is one of the candidate alternatives for SF 6 in a gas circuit breaker. First, we calculated 80%CO 2 + 10%O 2 + 10%C 5 F 10 O (C5-PFK) arc characteristics only by considering less than 8-atom molecules. However, it seems possible to produce more than nona-atomic molecules in the low-temperature region in 80%CO 2 + 10%O 2 + 10%C 5 F 10 O (C5-PFK) arcs. The present work further calculated the equilibrium composition of this gas mixture at 0.1 MPa with taking account more than nona-atomic molecules. Furthermore, their thermodynamic and transport properties were also computed with collision integrals between species considered. Using these properties, the arc temperature and gas flow fields were calculated using two-dimensional LTE model for a free recovery condition from dc 50 to 0 A. Results showed that a similar temperature decay was obtained for arcs in the 80%CO 2 + 10%O 2 + 10%C 5 F 10 O (C5-PFK) gas mixture to that for arcs in 100%CO 2 gas.