The influence of contacts erosion on the SF₆arc

Abstract

In circuit breakers, high temperature arcing may lead to material erosion at the contacts. In this paper, numerical investigations have been performed in order to study the arc behaviours under the influence of copper vapours contamination in a simple Laval nozzle. The arc is assumed to be in local thermodynamic equilibrium. The erosion rate is estimated by considering the energy balance processes at the contact surface. Computations have been performed by a commercial computational fluids dynamics package (PHOENICS). The effects of contact polarity have also been investigated. It has been found that the presence of copper vapours cools down the arc temperature at the region close to the contacts. However, at current zero, the copper vapours concentration is very low. Post arc simulation has been performed in order to determine the critical rate of rise of recovery voltage (RRRV). Good agreement has been achieved with the experimental measurement of RRRV. It has been predicted that the contact erosion has a negligible effect on the interruption capability of the breaker.

Prediction of the critical reduced electric field strength for carbon dioxide and its mixtures with copper vapor from Boltzmann analysis for a gas temperature range of 300 K to 4000 K at 0.4 MPa

“…2 Copper vapor inevitably enters the arcing chamber due to ablation of the contacts, and it may change the composition and properties of the arc and hot gas in the post-arc period. 3 However, the influence of copper vapor on the interruption capability and dielectric breakdown properties is still not clear. 1 SF 6 has excellent insulation and arc-quenching capabilities.…”

Simulation of the Influences of the Pressure Ratio and Cu Vapour on SF6Arc Characteristics

“…The Prandtl mixing length model is used in Ref. [9], which is also known as the zero equation model [11] . Although the computational cost of the zero equation model is economical, the turbulence parameter needs to be adjusted for a given geometry of the nozzle.…”

Changes of Electrical Conductivity and Temperature Caused by Electrode Erosion for Atmospheric Plasma Systems

“…Zhang et al [6] investigated the effects of electrode vapor on the behavior of a steady-state arc in a supersonic nozzle. Liau et al [7] performed a numerical simulation of a SF 6 arc with copper vapors within a Laval nozzle. Chevrier et al [8] studied the arc-contact interaction in * E-mail: yjkim@skku.edu; Fax: +82-31-290-7448 a SF 6 self-blast circuit breaker with the model, which is macroscopic and is based on an energy balance at the boundary between the electrical arc and the electrode.…”