The application of variable frequency drives in medium-power hoisting installations enables significant improvement in reliability indicators and enhancement of the system's dynamic characteristics. …

Analysis of materials on the accident rate shows that the cause of failure of electric motors of mining machines is mainly damage to the insulation of stator windings (80%), much less often - rotor cells (11%), even less often mechanical damage (9%). This allows us to outline the main ways to reduce the accident rate of electric motors of mining machines. Improvement of their operational reliability and increase of service life can be achieved by: 1) improving the thermal regime of electric motors by intensifying their cooling; 2) increasing the heat and moisture resistance of insulation; 3) improving protection; 4) creating “constant power” drive systems ...

When automating mine load hoisting with asynchronous drive the main difficulties arise usually at the end of hoisting, when static resistances variable in magnitude and sometimes in sign are combined with low speeds.In order to obtain relatively rigid mechanical characteristics of the drive, necessary to ensure a stable low speed during the movement of lifting vessels in unloading curves, several methods have been proposed and partially tested in recent years.

Advantages of automatic hoisting consisting in increase of productivity, increase of reliability of work and safety, and also release of labor of a highly skilled machinist and a great spread in the Soviet Union of hoisting installations with asynchronous motors make the problem of automation of hoisting with asynchronous drive very actual. The solution of this problem has been started since 1932-1933. However, despite the twenty-year period since the first studies on this issue, the problem has not been completely solved so far. The reason for this lies in the unfavorable mechanical properties of the induction motor, which make it difficult to automate the lifting, as well as in the known one-sidedness of the solutions offered so far, based, as a rule, on the use of mechanical shoe brakes during the deceleration period. In spite of numerous researches, conducted mainly by V. B. Umansky and V. S. Tulin, it is impossible to create a good solution. S. Tulin, it has not yet been possible to create good stroke controllers acting on the mechanical brake of a hoisting machine. And if the automation of starting the hoisting machine is solved today, the question of controlling the hoisting machine during deceleration requires theoretical and experimental study. The analysis of operation of various systems of hoisting automation, based on comparison of mechanical characteristics of various braking devices, allows us to critically evaluate these systems and outline new directions in solving the problem of automation of freight hoisting with asynchronous drive.

In conditions of coal mines regulation of centrifugal pumps is either not applied at all, or is carried out by a gate valve, which leads to deterioration of efficiency of the pumping unit and, consequently, to overconsumption of energy for drainage. As the survey data of a number of mines show, the nominal head of the installed pumps often significantly exceeds the head required to overcome static and dynamic resistances at the nominal capacity of the pumping unit. This, in turn, in order to avoid inadmissible overloading of the drive motor, leads to the need for prolonged operation of pumps with the gate valve closed, i.e. with significant unproductive losses. According to A. I. Veselov, the gauge nominal head of the installed pumps often significantly exceeds the head required to overcome the geodetic height of discharge, and the capacity of pumps is selected with a large reserve. Referring, for example, to the mines of Kizelovsky district, A. I. Veselov writes: “The largest dewatering installations of the mines named after V. I. Lenin and M. I. Lenin. V. I. Lenin and M. M. Volodarsky mines work with an excessive head reserve, and hence, of course, low efficiency of the unit. Lenin mine at the main pumping stations has an excessive installed capacity of pumps, which is equal to almost five times the normal inflow.