Self-Flow Generation Phenomena in a Gas Circuit Breaker Without Puffer Action

Study on the Arc Quenching Process in Gas Circuit Breakers

“…However, some reports have indicated that, as the arc's blocking of the entrance of the nozzle results in an increase in the pressure of the arc chamber, the interrupting capability at current zero is in fact increased. [1] This development reinforces arguments that the effect caused by the blocking of the nozzle should be included in any theoretical analysis of the arc quenching phenomenon. Despite this, it has so far proven difficult to include changes in the arc radius and the effects of the blocking of the nozzle during the arc quenching process in a heat analysis.…”

“…As is well known, three major effects should be included in the description of a thermal transfer; (1) the motion of the medium using thermal energy, (2) a thermal energy transfer using thermal conduction proportional to the thermal conductivity of the medium, and (3) the thermal energy transfer using radiation. These behaviors are described below: -+ div(PKM) = (1) p at at where, grad p -p ( u grad)Y (2) Mgrad (ph)+div(fi; + E-R(Tv p) (3) pressure, p gas density, = gas flow velocity/ K = mass flow A enthalpy of gas, E= electrical field strength, C = electrical conductivity T= gas temperature, R= energy loss by radiation 2.2 The simplified enthalpy arc model (modified) As an arc is a plasma that possesses a large amount of energy, the following assumption has been adopted: i) During the initial step, the arc has a cylindrical form with a length equal to the distance between two contacts, ii) Constant temperature channel, T independent of z, and of r over the channel area A(z), iii) the gas flows in a nozzle with nearly constant axial pressure gradient over the arc length. iv) The arc radius is limited during the stage where the pressure reaches the entrance of the nozzle, which then permits the arc characteristics such as arc temperature, arc energy and so on to be calculated using a numerical analysis based on the interaction between the heating caused by the arc and the cooling resulting from the gas flows.…”