Arc Erosion Behavior Research Articles

Polarity effect of unsymmetrical material combination on the arc erosion and contact resistance behavior

The arc duration, material transfer, contact morphology, surface composition, and contact resistance of dissimilar contact combinations of palladium to silver were experimentally examined with a breaking inductive load from 0.5 to 4.0 A for 6/spl times/10/sup 4/ operations in air at atmosphere pressure. The test results have led to the conclusion that polarity significantly affects are erosion and electrical contact resistance behavior. By utilizing results from a previous study, it is known that cathode materials have significant influence on are erosion, i.e., through material transfer, arc duration, and erosion patterns. Contact resistance, however, is dominated by the anode material due to surface contamination, specifically anode oxidation in the late gaseous phase. Also, evidence is found in this work that material transfer between two electrodes greatly influences are erosion and contact resistance behavior.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Static gap erosion of Ag-CdO electrodes

The arc erosion behavior of Ag-CdO electrodes has been investigated by static gap discharge experiments. By recording the breakdown voltage of each discharge, and thus the interelectrode gap distance, the erosion depth was continuously monitored. Based on the experimental data and a simple model, the mechanisms of erosion at different levels of arc energy were identified. When struck by low-energy arcs, the electrode erosion was found to be mainly due to vaporization, but when struck by high-energy arcs the electrode erosion was by melting and ablation. The efficiency of erosion was estimated to be 0.003 to 0.009, which suggests that most of the arc energy is dissipated in the interelectrode atmosphere and by conduction into the electrodes, and that only a small fraction of the arc energy actually causes electrode erosion. >

Metallurgical aspects of silver-based contact materials for air-break switching devices for power engineering

The properties of the contact materials Ag/CdO, Ag/SnO/sub 2/, Ag/Ni, Ag/C, and Ag/W are discussed on the basis of the metallurgical processes occurring due to the interaction of an electric arc with the contact material. In the case of Ag/CdO and Ag/SnO/sub 2/, the arc erosion behavior is characterized by the interplay between decomposition of the oxide component (energy consumption) and viscosity effects due to the oxide particles in suspension in the silver melt. With Ag/Ni the process of dissolution and reprecipitation of the Ni appears to be the dominant factor. The switching behavior of Ag/C is largely governed by the combustion reaction between the graphite particles and the oxygen of the atmosphere. The erosion resistance of Ag/W and Ag/WC, respectively, is mainly brought about by the high melting point of the W or WC component. By means of selected examples taken from the authors' research work and field experience, it is pointed out how the contact properties are influenced by the metallurgical mechanisms involved. It is shown that every material with a special advantage in one particular property also has a pronounced disadvantage in some other properties.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Comparison of the Inherent Arc Erosion Behaviors of Silver-Cadmium Oxide and Silver-Tin Oxide Contact Materials

Powder metallurgically produced silver-cadmium oxide and silver-tin oxide materials with equal volume percentages of oxide were electrically tested to evaluate and compare the effects of the different oxides on the arc erosion behaviors. The silver-tin oxide material had less steady-state erosion, better weld resistance, and higher contact resitance compared to silver-cadmium oxide. The eroded surface structures were examined and used to explain these quantitative results. The arc-affected erosion surfaces of the silver-tin oxide material consisted of silver, tin oxide, and porosity distributed across the contact surface, yielding Iow weld strengths but high contact resistance. The silver-cadmium oxide eroded surfaces had large elevated oxide-depleted areas which yielded Iow contact resistance but higher weld strengths. Theories of how these 'eroded surface structures developed under the given conditions are presented for the silver-cadmium oxide and the silver-tin oxide materials.