In a vacuum arc-suppression device, the contacts diverge in a negative pressure environment where the air density is very low. For exapmle, vacuum interrupter of Tavrida Electric contain high vacuum (10-6 Pa). The free path of a molecule reaches 50 m, and the free path of an electron reaches 300 m. Under such conditions, the electrical breakdown between the electrodes is difficult due to the absence of charge carriers. The breakdown voltage of a 1 mm long gap in vacuum reaches 100 kV. The process of combustion and extinguishing of the arc in a vacuum at alternating current is as follows. When the contacts open, the contact pressure continuously decreases and the transient resistance of the contacts increases and tends to infinity at a pressure equal to zero. Even at low currents at the moment of opening the contacts because of the release of large amounts of heat contact material melts and a liquid metal bridge is formed, which under the influence of high temperature heats up
Today, few publications devoted to the problems of the electric power industry do not touch upon the concept of "SMART GRID," which literally translates as "smart grid. This concept implies a new technology for controlling the power system , starting from the energy producer and ending with its end consumers. That is why the first term "SMART" is also regarded as an acronym for "Self Monitoring Analysis and Reporting Technology," and why we will use the term "SG" instead for short. The tasks solved by "SG" are traditional - energy saving and uninterrupted energy supply. Such tasks were set before, but the possibilities of its realization with the advent of such means of communication as the Internet have become truly revolutionary.