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Ekaterina S. Lyuminarskaja

Bauman Moscow State Technical University

DETERMINATION OF TRANSIENT RESISTANCE LOW-URRENT ELEKTRICCONTACTS IN DUSTY CONDITIONS THE CONTACT SURFACES

Abstract: Introduction. Now on transport, in automotive, aviation, space, householdand other vehicles the tiny mechanically managed switches are widely used. The small weightand small dimensions belong to their benefits. However bad contact connection can lead tofailure of devices on which work of all difficult technique depends. In household appliances itwill not lead to serious problems, but for transport failure of contact system can lead tocatastrophic consequences. The most important indicator of reliability of microswitches is non-failure operation of work. Failures of microswitches arise because of the thermal, electric,mechanical and chemical phenomena in a transitional zone of electric contacts. Now big
distribution was gained by low-current contacts. Refusals and failures in such contacts appeargenerally because of hit in intercontact space of dust and other pollution, formation of the filmswhich are not collapsing in case of short circuit of contacts, sudden change of force of pressingof contacts because of breakdown of an elastic element or an expansion spring.

In article the mathematical model of contact systems in case of failure on the exampleof modern electronic microswitches of rod type is provided.

Purpose. Creation of mathematical model of contact systems at failure on the exampleof modern electronic microswitches of rod type, research of operation of microswitches inactual practice operation.

Methodology. Theoretical methods of research with use of personal electroniccomputer were applied to achievement of an effective objective. The theory of contactinteraction of rough surfaces, the theory of electric contacts, methods of linear algebra, etc. havebeen used. The program complexes Mathcad, ANSYS were used. In case of pilot studiesmethods of mathematical statistics were applied.Results. In article the technique of determination of transitional resistance of low-current electric contacts considering possible dust content of contact surfaces, formation of
films on surfaces of contacts and change of parameters of a roughness of contact surfaces as aresult of plastic deformations is offered. For the studied contacts dependence of probability offailure on concentration of particles of dust is received.

Practical importance. The technique described in article allows to determine thetransitional resistance of electric contacts both during the normal work, and at failure.

Conclusion. Development of mathematical models of contacts at failure gives thechance to estimate reliability of connections in actual practice of work, to choose keyparameters of switching elements taking into account possible pollution, and also to developnew and to specify the available techniques of detection of failures.

Keywords: electrical contact, the transition zone, transition resistance, microswitch,switchin.

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