COMPARISON OF THE BEHAVIOR OF SF6 AND N2 BLAST ARCS AROUND CURRENT ZERO.

The behavior of SF//6 and N//2 blast arcs is theoretically investigated as the arc current is ramped down to zero from a high current steady state, followed by the application of a rate of rise of recovery voltage (RRRV). A one dimensional model based on the conservaiton equations of mass, momentum and energy is used to represent the acrc. Axial profiles of arc area, temperature, electric field, plasma velocity, power loss and time constant are reported for one current slope and its critical RRRV. Conclusions are drawn concerning turbulent arc cooling, the location of the arc interrupting zone, the critical post-zero current and the comparative interruption capabilities of N//2 and SF//6 blast arcs.