Of the many variants of earth protection devices, the optimal one for distribution networks is the zero-sequence power direction relay with electronic contactless circuit.

The study of transients of a certain level or phase of voltage at moments of short-circuit at multiple repetition is complicated by a number of difficulties: 1) short-circuit must occur each time at a given phase of voltage network; 2) the time of the closed state of the circuit (network) must exceed the duration of the transient with the subsequent automatic recovery of network parameters; observation or photographing the beginning of the leading edge of the transient process becomes impossible, since the entire process is conducted mainly with the help of cathode oscilloscopes.

Power System Modeling. Correct and reliable construction of power supply system and distribution of electric energy, research of modes of these systems as a whole and individual elements in particular, simplification of calculations and selection of optimal parameters can be achieved by physical modeling ...

The Research Laboratory of Automation and Telemechanics in Mining (ATM) was organized in 1957 and was attached to the Department of Mining Electrical Engineering until 1960, after which it was transferred to the Department of Automation of Production Processes. Four main sections were established in the laboratory: automation of mine electric drive control; automation of mine electrical network devices; telemechanics, signaling and communication; high-frequency technology and electronic devices.

Electromagnetic slip clutches (EMC) are widely used in various drives: mechanisms with fan load torque (electric drives of induced draft fans at power plants), ship propeller shafts. In ship propeller shaft drives, EMCs are particularly widespread and their power outputs reach several thousand horsepower. Recently, EMCs have been used for other types of electric drives : excavators, drilling machines, metal-cutting machines, etc.

A power three-phase transformer with smooth voltage regulation under load has a common magnetic core M with division into nine limbs arranged in a plane. The three main limbs 2, 5 and 8 are used for winding the primary phase windings W₁. The six additional limbs 1, 3, 4, 6, 7 and 9 house the DC biasing windings Wd. Secondary phase windings W₂ are located on nine limbs: three on the main limbs 2, 5, 8 and two on additional limbs 1, 3, 4, 6, 7 and 9. The compensating winding W_k is wound on all additional limbs. Deep smooth regulation of the secondary voltage of the transformer is carried out by changing the value of the DC current in the six DC biasing windings Wd.

In engineering calculations of dynamics of automatic control systems, the problem of determining the region of permissible parameter changes usually arises. For linear systems it is possible to obtain such a region by repeated machine solution of the system equation of motion or with the help of indirect methods (frequency, integral criteria, etc.). For nonlinear systems, this problem is often reduced to the construction of the region of permissible changes in the forms of nonlinear couplings, so indirect methods are either not applicable at all, or have an algorithm that is too complicated for practical application. The method of multiple partial solutions for nonlinear systems is obviously possible only in a few special cases. A number of similar problems are reduced to the task at hand: determining the influence of neglected couplings and the legitimacy of this or that approximation, estimating the accuracy of the approximate solution of the system's equation of motion, etc.

On December 27, 1955 died a major Soviet scientist, head of the Department of Mining Electrical Engineering of the Leningrad Mining Institute, Honored Worker of Science and Technology of the RSFSR, Doctor of Technical Sciences, Professor Felix N. Shklyarsky. Shklyarsky was born in 1883. He graduated from two higher educational institutions: the St. Petersburg Mining Institute in 1911 and the St. Petersburg Electrical Engineering Institute in 1917. Then for a number of years he worked as an engineer in Donbass, holding the positions of mining supervisor, ventilation superintendent and mine superintendent.

Mining technology, atmospheric and natural conditions in which the deposit is exploited determine the special specificity inherent in open-pit mines. The influence, role and significance of mining specificity are so significant and regular that in many cases they determine the basic principles of construction and operation of local mine power distribution systems within the established boundaries of open-pit mining of a deposit. However, the following fundamental issues remain unresolved in the mine electric power industry of open-pit mining: 1) local mine power distribution systems and types of open-pit networks for specific mining conditions constructed within the maximum established boundaries of open-pit mining of a deposit; 2) the optimal number and location of open-pit power supply points for periodically moving electrified mining machines in free running mode; 3) organization of planned operation of power distribution devices in open-pit mines with inconstant working horizons, with a periodically moving mining front and gradual advancement of excavator faces; 4) classification of mine power distribution systems and devices of local importance. The author's present work is devoted to the listed fundamental issues. Open-pit mining occurs in special, unique and difficult conditions, as a result of which, without preliminary generalized study and research of mining specifics, it is impossible to create new, more advanced power distribution systems and electrical equipment for them, as well as rationally plan and operate mining and power engineering in open-pit mines.