I would like to share with you 75 jubilee celebration of a talented scientist and one of my teachers of which you did not know, my Mother Dyna P. Karavashkina,
Many years ago we two undertook a study which, as you will make sure, still remains actual, because today contact sparking remains one of the main problems of electric engineering. Semiconductors only in some cases are able to substitute contacts, but not in case when we need to switch the circuit fully off. ;-)
Now I would like to suggest to your attention the paper written after materials of that old discovery,*Phenomena at electric contacts breaking direct-current inductive loads*
This paper is devoted to theoretical and experimental study of physical nature of unstable discharges arising in contact gaps when opening inductive load. We revealed that despite conventional opinion, showering arcs are alternating relaxations. Each of them consists of two stages: monotonous exponential growth of voltage related to the charging of parasitic capacitance of gap which is shunted by metallic bridges, and of high-frequency high-voltage oscillation process related to the high-frequency spark process within the gap. With it, metallic bridges are produced in each period of unstable discharges. We analyse the conditions and stipulate the physics of processes of such bridges formation. We established that the cause of bridge formation is the electric pressure in high-voltage oscillation process preceding the monotonous period of unstable discharge. The second cause are plasma jets able to strap even larger gaps than those typical for unstable discharges. The experimental results obtained after this theoretical study fully corroborated the described pattern of physical processes in showering arcs. On the basis of developed method to obtain the dynamic curve of breakdown voltage and noting the experimentally corroborated physics of processes, we have successfully carried out the work on practical protection of relay contacts working under inductive load, and presented the result of this protection.
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Hopefully, this study will be of your interest. It will be my pleasure if someone, having looked through our work, will get to see the world wider and more versatile, and that problems of physics are not confined to Lorentz transformation, Schwarzschild sphere and Schroedinger equation. ;-) Here also are very many subjects for development.
Best to you all,
Sergey B. Karavashkin
Head Laboratory SELF187 apt., 38 bldg. Prospect Gagarina Kharkov 61140 Ukraine
Phone: +38 (057) 73706624 e-mail: email@example.com , firstname.lastname@example.org