Performance Prediction Method Considering Shock Wave in Nozzle for High-Voltage Circuit Breaker

Interrupting-performance indexes that reflect the physical properties of gas flow are proposed for a breaker terminal fault of a high-voltage circuit breaker. A method of evaluating the shock wave and flow velocity was developed that uses a theoretical equation of supersonic flow which takes into account the nozzle’s shape and stagnation pressure. The predicted flow velocities and positions at which the shock wave forms have strong correlations with the test results

Particle composition of high-pressure SF6 plasma with electron temperature greater than gas temperature

Numerical computation was performed to derive particle compositions of high-pressure SF6 plasmas in which the electron temperature Te is greater than the gas temperature T g. The effective excitation temperature Tex for each of particles was proposed to express the distribution of particles in excited states. Furthermore, the relation equations for chemical equilibrium in a two-temperature plasma were developed on the basis of the second law of thermodynamics. At fixed Tg in the range of 6000-9000 K, the increasing Te from 9000-20 000 K encourages the dissociation and ionization of particles, causing the composition of SF6 plasma at 0.1 MPa to differ markedly from the composition under the condition of thermal equilibriu

Deviation from local thermal equilibrium in SF6 post-arc channel exposed to transient recovery voltage

Summary form only given. This paper describes the influence of applied electric field on properties of a SF6 post-arc channel. First, electrical conductivity, enthalpy and mass density of electron and heavy particles in a SF6 plasma were calculated as a functions of Te and Tg. Secondly, using this data, time variations in Te and Tg were computed in an SF6 plasma to which high electric field was applied. The calculated results revealed that applied electric field increased T e and caused deviation from local thermal equilibrium. Finally, time evolution of electrical conductivity σ of SF6 plasma exposed to electric field was also calculated. It was found that σ was enhanced by increasing Te particularly at initial temperature ranges 3000-3500 K and 5500-6500

Dominant spectra of background radiation in an SF6 post-arc channel

Composition of background spectra radiated from a SF6 post-arc channel after current zero was investigated. The radiation intensity of the background spectra at a wavelength of 455 nm around zero current was measured. The post-arc temperature was estimated from the intensity ratio of two spectral lines at 426.0 and 442.7 nm of iron used as an electrode material. The emission coefficients of not only the continuous spectra but also the S2 spectra due to the B3 Σu--X3Σg - transition were theoretically calculated as a function of temperature in the range of 3000-6000 K. The results indicated that the background spectra mainly consist of continuous spectra at temperatures above 4500 K, and of S2 spectra at temperatures below 4500 K. The temperature dependence of the calculated emission coefficients of the background spectra agreed fairly well with that of the measured radiation intensit