CC BY
3ТЕХНИЧЕСКИЕ НАУКИ (TECHNICAL SCIENCE)
УДК 1
Jumaeva D.J.
Doctor of Technical Sciences, Professor, Institute of General and Inorganic Chemistry Laboratory of Colloid Chemistry and Industrial Ecology
(Uzbekistan, Tashkent)
Toirov O.Z.
Doctor of Technical Sciences, Professor, Head of Department "Electrical Machines" Tashkent State Technical University (Uzbekistan, Tashkent)
Darxonova Sh.
Master Student of the Department "Electrical Machines" Tashkent State Technical University (Uzbekistan, Tashkent)
Joldasbaeva G.
Master Student of the Department "Electrical Machines" Tashkent State Technical University (Uzbekistan, Tashkent)
FUNCTIONS AND OPERATION CONDITIONS OF BENDING CABLES USED IN THE MINING INDUSTRY
Abstract: this article provides information about the functions of flexible cables used in the mining industry, as well as their use and properties.
Keywords: cable, polymer, mining, industrial, electrical, dynamic voltage/
In the mining industry, cables are used to distribute electricity and power mining-powered electric vehicles. In the mining industry, when mining mines, the electrical equipment moves towards the front of the work. Therefore, supply cables should be laid after cutters, combines, and so on. Cables experience dynamic loads, which can be divided into: Impact loads (accidental) - the impact of the rock as a result of loads resulting from the collapse of the rock, equipment impact, collision with mobile vehicles, etc., which leads to damage to the fiber insulation of the shell, periodic loads - repeated forces during the operation of the cable. These forces can cause the cable sheath to fail, causing the sheath or insulation to cut and puncture, and the insulation to break or rupture [1-4].
Cutting and puncturing of the sheath or insulation occurs as a result of the cable hitting the sharp edges of pieces of coal or stone. If the cable accidentally touches the sharp edges of the conveyor scrapers, the cable may be cut due to careless shocks with the work tool. Practice shows that such damage is the most common and dangerous. When the cable is pulled behind the mechanisms, the current-carrying fibers break or the insulation breaks. When the cable is pulled, various rocks may be left behind. In this case, if the cable continues to be pulled, significant voltage forces will occur, which can lead to disconnection of the entire cable or damage to the insulation. Crushing of cable insulation can occur when coal or rock falls, when the cable is moved by combines or other mechanisms. Depending on the magnitude of the loads caused by the explosion, the insulation may be completely or partially damaged. Figure 1 below shows an overview of flexible cables.
As it slides along the mining array, the cable inevitably takes on a wave-like shape, forming rings of different sizes. Under normal conditions, due to the elastic properties, these rings are corrected when tightened. However, if a large amount of rock falls into the loop formed while pulling the cable, the ring, which cannot be straightened, is tied to a special shaped knot under the influence. In this case, the cable insulation often cracks and the wires entering the fiber are severed, leading to a short circuit between the fibers [5-6]. Thus, the complex effects of torsional bending forces on mine cables can lead to mechanical damage or a significant reduction in service life, leading to failure of these cables. Even in the presence of minor mechanical damage, the wear of the cables is accelerated due to the ingress of moisture and dust into the damaged areas. Therefore, the mining industry has high requirements for high-voltage flexible cables in terms of mechanical strength, resistance to bending, bending. The climatic resilience characteristics of the cables are given in Table 1 below.
Table 1. Climate flexibility of cables
Climate index Designation
The climate is average У
2) In moderately cold climates УХЛ
wet-tropical ТВ
Dry, tropic ТС
Dry, wet-tropical Т
General climate О
For dry and water В
Location category
Outdoors 1
On the open air porch 2
Without heating system in indoor buildings 3
Buildings with heating system 4
Buildings with high humidity 5
The electrical and mechanical properties are related to the characteristics of the rubbers (Table 2). This type of rubber is produced on the basis of its composition with synthetic rubbers, which slightly increases the heat resistance of the rubber and reduces the corrosion of copper fiber. As a vulcanization activator, phenol-formaldehyde resins increase the vulcanization rate and heat resistance with sturam. These rubbers have operating temperatures up to 65°C. Necessary plastics is provided by means of softeners: kerosene, oil, Vaseline. The concentration of softeners, in addition to the required elasticity, sets the vulcanization rate.
Table 2. Electrical strength of rubbers
Types of rubber Epr,kB/M
(NK) 21
Synthetic isoprene (SKI-3(3D)) 17
Synthetic butadione (SKD) 20
Butadiene (SKS) 26
Butyl rubber 22-23
Ethylene-propylene (SKSP(T)) 25
Moisture resistance depends on the type of rubber, i.e. non-polar rubbers (NK, SKB, SKI) have less moisture permeability than polar rubbers. The amount of rubbers in these rubbers is 40-50%. Moisture absorption affects the type of filler, for example, the addition of talc reduces moisture absorption, but at the same time reduces the elasticity, so talc is added to the total volume of the filler in 50:70 oily compositions. Fillers are used in the same way as rubber for normal use.
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Dilnoza Jumayeva, Izzat Eshmetov, Berdah Jumabaev, Anvarkhodja Agzamkhodjayev Carbon adsorbents on the basis of brown coal of Angren for cleaning industrial wastewater, Journal of Chemical Technology and Metallurgy, 51, 2, 210-214 (2016). Dilnoza Jumaeva, Akmal Abdurakhimov, Khodjiakbar Abdurakhimov, Nigora Rakhmatullaeva, Olimjon Toirov, Energy of adsorption of an adsorbent in solving environmental problems, E3S Web of Conferences, 288, 01082 (2021), SUSE-2021, https://doi.org/10.1051/e3sconf/202128801082
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