Study of the arc-electrode interaction in a SF₆self-blast circuit breaker

Abstract

To study the interaction between the electrode and the electrical arc in a SF6 self-blast circuit breaker, a coupling between experimental and theoretical approaches is proposed. The experimental approach allows physical variables such as the temperature just below the contact surface and the total metallic vapour mass in the electrical arc to be measured. The theoretical study is based on a hydrodynamic model for electrical arc modelling, which takes into account Joule heating, radiation and real-gas effects. The arc/electrode interaction model is built on an energy balance at the boundary between the gas flow (the arc) and the electrode (cathode or anode). The validation is obtained through comparisons between measured and calculated results.

Injectable chitosan-platelet-rich plasma implants to promote tissue regeneration:in vitroproperties,in vivoresidence, degradation, cell recruitment and vascularization

“…Chitosan-GP/blood implants were injected in a liquid format over surgically prepared cartilage defects where they solidified in situ and improved repair compared to bone marrow stimulation (microfracture) (Hoemann et al, 2005;Hoemann et al, 2007). Some of the mechanisms responsible for improved repair in vivo include increased recruitment of cells from the subchondral bone (Chevrier et al, 2007), increased transient vascularization and bone remodeling (Chevrier et al, 2007;Hoemann et al, 2007;Hoemann et al, 2010), promotion of a beneficial phenotype of alternatively activated macrophages (Hoemann et al, 2010) and increased osteoclast activity, leading to better repair tissue integration (Chen et al, 2011). The use of chitosan-GP/blood implants (BST-CarGel® a medical device from Smith and Nephew, MA, USA) in conjunction with microfracture was also found to be superior to microfracture alone in a randomized controlled clinical trial (Stanish et al, 2013;Shive et al, 2015), leading to the approval and distribution of this formulation for cartilage repair in several countries.…”

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

“…1 Copper and its alloys are widely used in contacts on account of their excellent thermal and electrical conductivity. 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.…”

The effects of metal vapour in arc welding

“…The importance of metal vapour in the arcs that are formed by erosion of the electrodes in circuit breakers has been demonstrated experimentally (e.g. [14]). Computational studies have been presented of the influence of electrode vaporization in high-voltage SF 6 [15,16] and low-voltage air circuit breakers [17] and of the evaporation of metal droplets ejected from the contacts in gas-blast circuit breakers [18].…”