The manuscript of the translation of the article by the Swedish mineralogist Thorburn Bergman, made at the Nerchinsk mines in 1780 by A.M.Karamyshev and E.E.Barbot de Marney, kept in the Main Library of SPGGI, is examined in detail for the first time. The manuscript is the first work in Russian devoted to the soldering tube, in the terms of the 18th century - an "experimental fifka". A full bibliographic description of the manuscript is given and the circle of persons whose fates are connected with this manuscript is indicated.
The article continues the series of publications in "Notes of the Leningrad Mining Institute" and interdepartmental thematic collections, aimed at popularizing the collection of the Rare Books Department (RBD) of the Main Library (ML) of LGI, the oldest mining-technical library of the country, and attracting attention to rare and valuable editions of works of both Russian and foreign authors of all those interested in the history of geological knowledge.
The extraction of minerals, especially metal ores, from ancient times has been associated with a number of labor-intensive processes, such as dredging, raising the fossil to the surface, and since the middle of the 17th century, the ventilation of mines.
A nonlinear inductive shunt can be used to protect the longitudinal-capacitive compensation units: CPCs from overvoltages when the current in the circuit increases. Strict calculation of network operation modes with the installation of longitudinal CPC compensation in this case is quite a difficult task ...
Installations of longitudinal-capacitive compensation CPC for prevention of undesirable modes sometimes it is expedient to shunt by inductive nonlinear element ...
Voltage losses due to the large length of mine distribution networks, prevent the normal operation of electric drives of mining machines and mechanisms. One of the effective means of compensation of voltage losses, and hence a means of ensuring normal operation of electric motors in such networks, is longitudinal capacitive compensation. Its application, however, is complicated by self-excitation of induction motors. The effect of self-excitation can be so significant that normal operation of electric motors, despite compensation of voltage losses, will be impossible ....
When an unloaded transformer is switched on through the capacitors of the CPC longitudinal compensation unit, undamped resonant oscillations can occur in the circuit. The frequency of these oscillations is usually 1/3 of the mains frequency (in case of subharmonic resonance) or equal to the mains frequency (in case of ferroresonance of voltages). Resonant oscillations are known to be accompanied by a sharp increase in transformer magnetizing current and overvoltages both on the CPC itself and on the transformer ...
The installation of longitudinal compensation (LCC) of voltage losses in the distribution network of the mining site was first tested in production conditions at one of the sites of the Kirov mine of the Slantsy Combine in 1964. In the experimental operation of the CPC proved the feasibility and efficiency of automatic voltage regulation by series capacitors in the network of the site. Inclusion of the longitudinal compensation unit allows to get voltage increase at the longwall face distribution point by 20-25% at engine starts and by 10-15% at nominal load ...
Issues of automatic voltage regulation in local electrical networks are an important part of the overall problem of complex mechanization and automation of production processes in the mining industry. Stable voltage level is necessary for stable operation of automatic devices, more complete utilization of natural mechanical properties of electric drives, reduction/loss of electric energy in local distribution networks.
