Многочерпаковые электродраги представляют собой мощные пловучие агрегаты, работающие на россыпных месторождениях по добыче золота, платины и других полезных ископаемых. Режимы работы электроприводов основных механизмов драги изучены пока недостаточно. В настоящей статье в результате анализа построенных и снятых с натуры нагрузочных диаграмм предлагается возможная методика выбора мощности главного электродвигателя драги — двигателя ее черпаковой цепи.
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.
Определение мощности главного привода многочерпаковых электрических драг, т. е. привода их черпакового устройства, встречает следующие затруднения. 1. Недостаточная изученность физических свойств грунтов драгируемых россыпей приводит к тому, что усилие резания грунтов черпаками с необходимой степенью точности не может быть определено. Грунты, в основном, не являются однородными. Как следует из классификации грунтов для дражных работ (табл. 1), установленной в 1937 г., грунты могут содержать торф, пески, глины, щебень, песчаник, валуны, изверженные породы и другие компоненты, причем процентный состав их колеблется в широких пределах. Поэтому для подобных грунтов пользоваться физическими константами, полученными при испытании однородных грунтов, будет не совсем правильным. 2. При работе драги могут встречаться различные препятствия (крупные валуны, крепежный лес старых выработок и др.), которые вызывают перегрузки двигателя черпакового устройства. Длительность и величина перегрузок теоретически не могут быть учтены. Выявление характера подобных перегрузок и величины усилия резания может быть осуществлено с помощью нагрузочных диаграмм, снятых самопишущими электрическими измерительными приборами. Выбор типа привода черпакового устройства представляет меньшие затруднения.
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.
The power of the scraper winch engine is known to be determined based on the expression ... (see article). Thus, it is assumed that the scraper traction force is constant during the entire time of its operation, i.e., in essence, the choice of engine power for the scraper drive is carried out as in a long-term operating mode. In fact, the operating mode of the scraper winch drive should be classified as intermittent-short-term, since the periods of working and idle runs of the scraper alternate, which is evident from the load diagrams given below, taken by the author in the mines of the Cheryomkhov coal basin. Therefore, from the point of view of the operating mode, the choice of scraper winch engine power based on expression (1) can hardly be recommended. In this sense, it would be most appropriate, using load diagrams similar to the one given in the figure, to determine the drive power as root mean square. Unfortunately, this is practically almost impossible to implement, since the scraping conditions are so varied with respect to the angle of inclination of the plane of movement of the load, the nature of the scraped material, the length of the delivery route, etc., that in each specific case it would be necessary to have either load diagrams taken from nature, or a large number of load graphs recorded on tape, on the basis of which experimental coefficients could be derived.
As is known, the following resistances act during the movement of a loaded scraper: 1. resistance to movement of the material captured by the scraper, 2. resistance to movement of the scraper itself, 3. resistance to movement of the ropes, 4. resistance in the blocks and from the rigidity of the ropes, 5. resistance to scooping up the scraped material. During the movement of an empty scraper, only resistances (2), (3) and (4) act, resistances (1) and (5) are equal to zero. However, the pattern of change in the resistance to movement of the material captured by the scraper (hereinafter designated z₁) and the resistance to scooping up the scraped material (hereinafter designated z₅) during filling the scraper has not been studied in essence. Meanwhile, knowledge of this pattern is highly desirable from the point of view of overloading the scraper winch engine and, consequently, a more theoretically justified choice of the power of this engine. Based on existing data on the operation of scraper installations, in particular, on the existing coefficients friction and the values of the specific work of scooping, below we offer the following interpretation of the pattern of change during filling of the scraper of the two types of resistance indicated above.
