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Date submitted2019-05-05
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Date accepted2019-07-03
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Date published2019-10-23
Scraper Face Conveyors Dynamic Load Control
- Authors:
- E. K. Eshchin
The task of controlling the dynamic loading of scraper face conveyors (SC) is considered and the unsatisfactory state of loading of mechanical and electrical components of the SC is recorded. The possibility of the appearance of a self-oscillatory nature of the entire system load due to the peculiarities of the movement of the traction chain along the lattice frame of the SC is indicated. The property of the system is noted – the cyclic nature of the loading of the circuit during movement, which causes energy exchange processes between the mechanical and electromotive components of the conveyor (when using the head and tail electric drives) through the common cable network of the power supply system of the SC. A high level of dynamic loading of the electromechanical system causes the problem of eliminating the self-oscillating operating mode of the SC that generates it which is proposed to be solved by changing the angular rotation speeds of the SC drive sprockets. Angular speeds can be changed by applying frequency control of asynchronous electric motors. The efficiency of setting the frequency of electric motor stator currents of the head and tail drives of the conveyor is established in proportion to the frequency of rotors rotation to eliminate self- oscillating modes of operation in the main operating mode. The possibility of reducing the starting shock values of the electromagnetic moments of electric motors is considered. The results of the calculation of the start-up and liquidation of the self-oscillating operating mode are presented on the example of the scraper face conveyor Anzhera-34. The results of calculations of the start-up modes and the main operational transportation of coal in an uncontrolled mode of operation and after the introduction of control are compared, based on which it is concluded that it is advisable to use active control of the dynamic loading ofSC.
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Date submitted1951-07-05
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Date accepted1951-09-25
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Date published1952-03-26
Testing of an electric motor with moisture-resistant insulation of a submersible motor-pump with a capacity of Q = 100 m³/hour at a pressure of H = 100 m
- Authors:
- L. F. Shklyarskii
This work was completed in 1950 as a joint venture between the Department of Mining Electrical Engineering of the Leningrad Mining Institute and one of the coal trusts. The electric motor of a submersible motor-pump designed for pumping water from wells in the conditions of the Leningrad coal deposit was tested. Both the pump and the electric motor are completely immersed in water during operation, which significantly distinguishes the design of this motor-pump from all existing ones, in which the electric motor is installed at the top of the wellhead and connected to the pump submerged in water by means of a long shaft (motor-pumps of the ATN type, etc.). The electric motor is made with moisture-resistant insulation of an open type without a hermetic shell.
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Date submitted1950-07-21
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Date accepted1950-09-18
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Date published1951-04-30
Testing the electric motors with new moisture-resistant insulation of submersible motor-pumps with a capacity of Q = 30 m3/hour
- Authors:
- L. F. Shklyarskii
The present work is the result of creative collaboration of the Department of Mining Electrical Engineering of the Leningrad Mining Institute with one of the coal trusts. Electric motors of two submersible motor-pumps were tested. The design data of both motor-pumps are absolutely identical. Only their electrical parts differ slightly: the stator of the electric motor of one of them (motor-pump No. 7) has slightly larger slot dimensions than the stator of the electric motor of the other motor-pump (motor-pump No. 9). Therefore, 16 wires are laid in each slot of the stator of the electric motor of motor-pump No. 7, and 11 wires are laid in the electric motor of motor-pump No. 9. The main data of the submersible motor-pumps with a star connection of the stator winding of the electric motor are as follows: electric motor power on the shaft Pn = 9.2 kW; voltage Un = 380 V; revolutions n = 2900 rpm. Three-phase asynchronous short-circuited electric motor (Fig. 1); pump capacity Qn = 30 m3/hour; pump head Na = 50 m. The total height of the motor-pump is 1400 mm, the height of the electric motor is 930 mm, the diameter of the unit is 183 mm. The electrical and mechanical parts of the submersible motor-pumps are manufactured by the assembly and mechanical workshops of the trust. Submersible motor-pumps of the proposed design, used for pumping water from wells, compare favorably with those currently existing in the following features.