Аналіз, характеристика та розрахунок параметрів електродів в процесі розмикання контактів

Анотація

Analysis, characterization and calculation of the parameters of electrodes in the process of opening the contacts

1. A.   Mrachkovskyi, M. Chembay

Modern domestic switching devices have low reliability and service life when used in specific operating conditions. So, the life of these devices is 0.5-3 years, and is much lower than their technical resource.

In the manufacture of electrical apparatus, about 65% of the cost of materials is made on the basis of silver contacts. Such contact materials are noted not only by high cost, but also low corrosion resistance when operated in aggressive environments.

Since silver is not extracted in our country, and in the conditions of a significant rise in the cost of noble metals, there is an urgent need to create environmentally friendly and erosion-resistant composite contact materials.

Experimental part of laboratory research of switching devices was carried out in the categories of application АС-3 and АС-4 on specialized stands. The analysis of thermal processes in switching devices was carried out by the method of solving the nonlinear heat conductivity problem of a semi-infinite body, taking into account energy expenditure. The processing of research results was carried out using mathematical statistics using computer technology.

The purpose of the study is to analyze and characterize the factors in the process of opening the contacts and to calculate the parameters of the electrodes.

Material of contact-details of switching devices with heterogeneous microstructure has increased electroresistance stability. In order to determine the temperature regime of the contact-details of the relay at current switching, the heat equation of the spherical coordinates was solved. The depth of the material's melting contact details depends on the energy of the arc, the physical-mechanical properties of the contact material, the time of burning the arc and is determined after mathematical transformations.

The estimation of the maximum surface temperature of the contact parts is derived from the equation of the thermal energy balance on the electrodes; the theoretical data from the determination of the value of electrical erosion of the contact parts, taking into account the electrophysical and mechanical properties of the contact materials, make it possible to determine the service life of the contact details, which coincides with the experimental data obtained when testing devices on switching stability.

Conclusions and perspectives. When opening the electrodes, conditions for the rapid heating of contact areas may be created, as their nature depends on many factors and the mathematical expression of such processes may have some errors.