Introduction and Survey: Physical and Network Phenomena

Predominant reaction products and dielectric breakdown properties of gas mixtures consisting of SF6 and ablation products of C2F4/BN in the temperature range of 300–3000 K

“…Figure 4 shows the impact of ionization cross section by electron on the predominant chemical species such as SF 6 , SF 2 , S 2 , CF 4 and BF 3 . The cross section σ BF3,i for BF 3 is larger than σ CF4,i(1) for CF 4 at the electron energy above 30 eV, but the cross section σ N2,i for N 2 is smaller than σ CF4,i (1) .…”

“…SF 6 circuit breakers interrupt the large alternating currents arising from electric power transmission system faults by utilizing the transient response of arc discharges established between electrical contacts. The circuit breaker must successfully operate during two periods: (i) the thermal recovery period that persists for several microseconds after the current zero at the end of the current wave, and (ii) the dielectric recovery period following the thermal recovery period [1,2].…”

“…During the thermal recovery period, the arc discharge behaves as a conductive medium and the arc temperature is rapidly cooled from more than 10 000 K to approximately 5000 K to reduce the electrical conductance of the arc, which is affected by the energy balance in the arc [1]. The thermodynamic, transport and radiative properties at the aforementioned high temperatures are very important to determine the arc transient behaviors [3].…”

“…In contrast, during the dielectric recovery period, the hightemperature gas at temperatures of several thousand kelvins or lower remains between the electrical contacts. While the gas at these temperatures no longer has electrical conductance, the gas must be maintained without dielectric breakdown against a transient recovery voltage induced by the electrical system [1]. The dielectric breakdown occurs due to electron production and loss through collision ionization and electron attachment processes in the gas.…”

Two-dimensional electron density characterisation of arc interruption phenomenon in current-zero phase

“…At the AC current-zero points, the electrical currents are interrupted temporarily. The power networks react to this temporary current interruption by transient recovery voltage (TRV) across the main contacts of the circuit breakers [5,6]. It has been conventionally considered that if a rising rate of the TRV is greater than a critical value, arc discharges are reignited immediately after the current zero due to ohmic heating of the residual plasmas, which is caused by the TRV application [7].…”