Experimental and theoretical investigation of an enclosed free burning arc in SF₆

Abstract

The behaviour of a free burning SF6 arc in a two-volume cylindrical chamber, which simulates the initial arcing in a modern high voltage auto-expansion circuit breaker, has been investigated both experimentally and theoretically. Arc voltage and pressure variations at four strategically chosen locations in the chamber were measured for electrode gap lengths of 30, 40 and 50 mm in the peak current range from 5 to 20 kA of a positive half-cycle alternating current at 50 Hz. A simplified model for free burning arcs in an enclosure was developed by radially integrating the governing equations under the assumptions of a uniform radial temperature profile and a variable radial profile of the axial velocity (equation (1)) in the arc. The effects of Lorentz force, Ohmic heating, radiative energy transfer, and turbulence enhanced momentum exchange are taken into account. The computed arc voltage and pressure variation in the chamber agree with the experimental results within the estimated range of uncertainty.

A comparison of three radiation models for the calculation of nozzle arcs

“…The arcs in rotating arc/hybrid circuit breakers often burn freely. In order to test the suitability of the model of Zhang et al for such arcing situations, simulations were carried out for the high current free burning SF 6 arc in the arcing arrangements of Yan et al [24]. The computed results suggest that the model of Zhang et al is less successful in modelling this type of arc.…”

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

“…This current shape was used to minimize contact erosion and gas decomposition during the opening phase. A similar experimental approach was used by Yan et al [11].…”

Electrical and thermal conductivities of high-temperature CO2–CF3I mixture and transient conductance of residual arc during its extinction process

“…Moreover the following assumptions (a) and (b) were made: (a) LTE is established in the arc and (b) the arc has an axis-symmetry distribution of temperature. The assumption of the LTE was adopted on the basis of three reasons: (i) most research works also use the thermodynamic and the transport properties derived under the LTE to study the arc extinction phenomena at pressures of 0.1 MPa or higher [21,26,27,[54][55][56][57][58][59], (ii) the present study was aimed at finding out the effect of CF 3 I addition on an arc extinction and (iii) the assumption of the LTE facilitated the calculation procedure in comparison with that for a two-temperature arc.…”