Resistance change of contact groups of low-voltage electrical apparatus: Determining the laws

The main Russian and foreign manufacturers of low-voltage electrical devices - circuit breakers, fuses, magnetic starters, knife switches and packet switches are presented. The data of experiments for determining the resistance values of contact groups of low-voltage switching equipment are considered. The design features of the devices that determine the value of the resistances of the power circuits of low-voltage equipment are investigated and a classification is proposed depending on the design elements of the devices. A methodological approach and an algorithm for experiments and detailed analysis of the contact groups of devices are given. Experimental schemes for the study of contact groups are proposed. The data of the conducted experiments on the study of contact groups and the resistance values as a function of the flowing currents are shown. During the experiments it is revealed that the value of the resistance of the contacts changes depending on the value, type and time of exposure to current within +/-5 %. The laws that characterize the ratio of the resistance values of the structural components of devices (contact systems, thermal relay, coil of the maximum relay) have been revealed and defined. Empirical expressions and graphical dependences of the resistances of contacts and contact systems are obtained as a function of the magnitude of the rated currents of low-voltage contact equipment. The minimum sample size of the number of devices during experimental research is determined, sufficient to calculate the mathematical expectation of the resistances of the contact connections of the devices with a given accuracy. As a result of experimental studies, it is revealed that the resistance value of contacts and contact joints can increase during operation by 2-2.5 times. The established dependences of the change in contact resistance can be used to predict the technical state of electrical installations of intrashop low-voltage networks, to clarify the amount of electricity losses in shop networks up to 1 kV, and can also be used as an additional regulation for maintenance and scheduled preventive maintenance.

Analysis of XLPE cable parameters subject to thermo aging

Modern marine vessels use electrically driven rudders; cruise liners, gas carriers, tankers are equipped with Azipod systems manufactured by the Swedish-Swiss company ABB. Gondola-type propellers make it possible to break ice when the vessel is moving astern, therefore such vessels are used for work on the Northern Sea Route, in particular, when working on the Yamal LNG project. The 22MW Azipod propulsion system rotates 360° and enables difficult maneuvering without the assistance of tugs. When operating such propellers, powerful diesel generators are installed on the ship. For the transmission of electricity, ship cables are used, which are subject to increased requirements that meet the standard of the International Electrotechnical Commission. Modern marine vessels are equipped with XLPE or EPDM insulated cable lines; industrial production of these cables is carried out in the Russian Federation. In the course of the study, a method for auditing the state of insulation has been considered based on an assessment of the change in the tangent of the angle of dielectric losses in the process of thermal aging of the cable of the PvBPng(A)-HF brand. Measurements of the tangent of the dielectric losses' angle have been carried out with a Tangens-2000 insulation parameter meter.

Analysis of depolymerization of insulating compositions of electric motor windings based on ultrasonic radiation

This work is a continuation of the fundamental study on implementing an innovative method of repairing electric motors using ultrasound. A study of the method of dismantling windings based on ultrasound has been carried out for the purpose of energy efficiency, environmental friendliness and less time spent on the repair cycle of electric motors in terms of removing the stator winding. The investigated dismantling method is optimal for a number of technical issues in comparison with the existing methods for dismantling electric motor windings. In the work, the main focus is on the material of the winding insulation. Lacquer and compound types of insulation of industrial electric motors, which are the main ones everywhere, have been analyzed. The analysis of the impregnating electrical insulating compositions of the stator windings of electric motors and the influence of ultrasound on them during dismantling of the windings of electric motors at different levels of influence of forcing factors: duration and power of ultrasonic action, concentration and temperature of the working solution. The applied mathematical software systems for calculation and modeling guarantee the reliability and rationality of the results of the experiments obtained during the work. A system of equations has been modeled and models of the effect of useful factors relative to each other have been constructed, the results obtained have been optimized and the optimal parameters of both varnish and compound insulation systems have been identified. The optimal parameters of the investigated types of insulation show encouraging results on many important points: duration, energy consumption, environmental friendliness.

Investigation of the chemical composition of pumpkin pulp as a basis for soft drinks

Pumpkin fruits ( Cucurbita spp.) have a number of advantages and high technological potential, thanks to almost universal cultivation in a wide range of agro-climatic conditions, the ability to long-term storage, the content of dietary fibers, pectin and other polysaccharides, carotenoids, polyphenolic substances, vitamins, which cause a wide range of physiological orientation. In the process of researching the composition of local cultivars of pumpkin and the world experience of using Cucurbita spp. in the composition of food products, the need to use this ingredient in beverage recipes has been substantiated. The content of dry substances in the pumpkin samples is from 8.18 % ("Gribovskaya") to 11.6 % ("Orange bush"). The maximum sugar content is distinguished by the varieties "Winter Sweet" (6.87 %) and "Orange Bush" (7.40 %). The content of BAS-antioxidants is (without visible difference depending on the growing region): carotenoids from 1.3 mg/100 g in "Gribovskaya" to 2.0 mg/100 g - "Orange bush"; ascorbic acid - 8.7 mg/100 g in "Rossiyanka" to 14.2 mg/100 g - "Orange bush". Today all parts of the pumpkin fruit are used: the bark is a raw material for the production of feed flour and a substrate for the cultivation of lactobacilli, the seeds are traditionally used to produce pumpkin oil and flour, the pulp of the fruit is a raw material for juice-containing products, purees, carotenoid-containing and polysaccharide extracts, pectin, concentrates of first and second dishes, snack products, pasta, bakery, confectionery and meat products, etc.

Application of the linear method of discriminant analysis of reflectance spectra in the near infrared region for the species identification of fish of the Salmonidae family

It is well known that fish belonging to the Salmonidae family differ in their nutritional value. Anatomical and morphological features of different salmon species have a certain similarity; therefore, representatives of this family are most often falsified. Assortment falsification of products from fish of this family is usually carried out by replacing more valuable species with cheaper ones with a reduced nutritional value. Most often, counterfeiting of Atlantic salmon (salmon) by Far Eastern ones (chum salmon, pink salmon, chinook salmon, coho salmon) is found. Near infrared spectroscopy (NIR) is now increasingly used for identification and authentication of closely related organisms, in some cases being a rapid method replacing genetic analysis. We have obtained diffusion reflectance spectra of NIR radiation for three species of fish from the Northern Basin belonging to the salmon family. The best classification by fish species has been obtained by analyzing the NIR spectra of pre-dried fat-free muscle tissue samples. In case of wet samples, the observed differences are less significant, up to insignificant differences in individual values from neighboring clusters. The possibility of using the method of linear discriminant analysis of the NIR reflection spectra of muscle proteins for the species identification of fish has been shown.

Specialized sports nutrition products using protein hydrolysis compositions of collagen-containing fish raw materials

The development of specialized sports nutrition with components of collagen-containing fish raw materials is due to the shortage of domestic products of this group, the problem of fish waste processing, scientific data on bioactive peptides of marine origin. Low-molecular active peptides and protein-mineral compositions in the form of powder and liquid dietary supplements were obtained from the scales of sardine and sardinella by methods of deep hydrolysis. During the hydrolysis of raw materials, fermentolysis was carried out with the Alcalase 2.5L enzyme, thermohydrolysis - at temperatures of 130-140 °C. The chemical composition of the scales of two fish species, the products of its hydrolysis, and the amino acid composition of its proteins have been studied. The amount of low-molecular-weight peptides in hydrolysates of sardine scales was investigated by various methods of hydrolysis. Rational methods of hydrolysis of scales - enzymatic and enzymatic-thermal - have been substantiated. They make it possible to obtain protein supplements with protein content of 83.9-85.2 % with a proportion of active peptides with a molecular weight of less than 10 kDa 91.7-98.1 %. A technology for obtaining protein supplements from fish scales has been developed, and their amino acid composition has been studied. The presence of irreplaceable and ergogenic amino acids, accompanying nitrogenous compounds, valuable in sports nutrition, was shown in the peptide supplement. An increased content of calcium, phosphorus and magnesium in the protein-mineral dietary supplement being important for the musculoskeletal tissues of an athlete has been established. On the basis of protein supplements in dry and liquid forms with the addition of beekeeping products, the technology of chewing marmalade for sports nutrition has been developed. Bioproduct "Apikolltonus" belongs to the class of gainers with a protein content of 20.5 %, a carbohydrate of 41.6 % with an amino acid value of BCAA (isoleucine : leucine : valine) 2 : 1 : 1.5. A multicomponent bar for sports nutrition has been developed using protein hydrolysates of scales, flaxseed and apple cakes, and pine nuts. The bar is functional in terms of the content of calcium and phosphorus, dietary fiber, flavonoids, and vitamin E. Recommendations for the use of new sports nutrition products are substantiated.

Production technology and quality assessment of milk shakes for baby food with vitamin complex enrichment

Diversification of dairy products for baby food is a topical trend in the development of the dairy industry. In the process of producing an ultra-heat-treated (UHT) milkshake, milk with a mass fraction of fat 3.5 %, skim milk with a mass fraction of fat 0.5 %, fruit filling "Cherry" and a vitamin premix are used. The technological process of production includes the acceptance of raw materials, assessment of their quality in accordance with regulatory documents; heat treatment of raw milk; preparation of a normalized mixture; adding ingredients. The prepared mixture is sent for deaeration to a flow-through apparatus, then to a homogenizer, where it is subjected to ultra-pasteurization at a temperature of 136 ± 2 °C with a holding time of 4 ± 1 s. The final stage of cocktail production is packaging and intermediate storage. The resulting product was tested in the laboratory for organoleptic and physicochemical indicators. During the experiments, it has been found that the taste, smell, colour, appearance and consistency meet the requirements of state standards. The content of protein, fat, carbohydrates, calcium and titratable acidity are within acceptable values; the content of vitamins A, D, E, B is higher than the minimum values. The research results on safety indicators meet the requirements of technical regulations. Antibiotics, GMO-derived materials and preservatives are not found in the product. The energy value of the baby milk shake is 63.7 kcal (266.6 kJ/100 g of product).

Effects of bioactive compounds upon the deterioration of the chilled mechanically deboned poultry meat during storage

Mechanically deboned poultry meat is a valuable protein containing raw material widely used for the production of meat products. However, it does not have a high resistance to oxidation; therefore, various antioxidants including those of natural origin are used in its composition. The article provides information on the advisability of using rosemary extract and dihydroquercetin to stabilize lipids and interrupt hydrolytic and chain oxidative processes in mechanically deboned poultry meat. The permissible storage time for mechanically deboned poultry meat using the rosemary extract and dihydroquercetin in a chilled state is 96 hours. Research has been carried out on the oxidative processes of the fatty complex of mechanically deboned poultry meat during the refrigerated storage period. Antioxidants prevent the accumulation of peroxides: in the samples with their use, the peroxide number reaches critical values on 6-7 day of storage, without their use - on 3 day of storage. For all samples, a gradual increase in the acid number has been observed; however, for samples without antioxidants its values reach a critical level on the 4 day of storage, with the use of antioxidants - on the 7 day. The active formation of secondary oxidation products has begun from the second day of storage and reached the limit of permissible values in samples without antioxidants after 3 days of storage. In samples with antioxidants, the thiobarbituric number reaches a critical value on the 6 day. It has also been shown that the use of antioxidants contributes to the preservation of sensorial indicators (colour, odour) improving the quality of products. The efficiency of using the rosemary extract and dihydroquercetin as inhibitors of the oxidation of mechanically deboned poultry meat has been confirmed.

Fatty acid composition of yogurt drink based on mare's milk

In accordance with the local climatic conditions and folk traditions in the Republic of Bashkortostan, dairy horse breeding occupies a leading position. Mare's milk is a unique raw material for the production of a wide variety of highly nutritious, complete and easily digestible food products. Scientists recommend mare's milk as a medicinal and dietary product. The paper presents a yogurt recipe developed on the basis of a composition using mare's milk. The composition received patent No 2677219 ( Composition…, 2019 ). It is known that mare's milk fat is rich in polyunsaturated fatty acids, which are of particular physiological importance for the human body. There is a need to ration and ensure a constant intake of polyunsaturated fatty acids of the ω-3 family with food. The purpose of this work is to study the fatty acid composition of yoghurt. To obtain a fermented milk product, milk from Bashkir mares was used as raw material. The production and research of prototypes of yoghurt were carried out on the basis of the Faculty of Food Technologies of the Bashkir State Agrarian University. The determination of the fatty acid composition of the yoghurt sample took place in the accredited testing laboratory centre "Federal Research Centre for Nutrition and Biotechnology" (Moscow). The use of mare's milk allows one to change the fatty acid composition of the finished fermented milk product. Analysis of the fatty acid composition of the sample has showed that it has a high content of oleic, γ-linolenic, α-linolenic and arachidonic acids.

Development of flour confectionery products with reduced sugar content

The search for equivalent flavoring sugar substitutes of a non-sugar nature is an urgent direction in the development of the technology of flour confectionery products. In the course of research, a gingerbread recipe has been developed with a partial replacement of the prescription sugar with a 15 % solution of sucralose in glycerin, which most closely correspond to the organoleptic characteristics (taste, smell, texture) of traditional flour confectionery products. The results of the organoleptic evaluation of coded prototypes of gingerbread with the involvement of experts have shown that a decrease in sugar concentration by 25 % does not lead to a statistically significant change in organoleptic parameters in comparison with control samples. Substitution of more than 30 % sugar leads to an increase in the plasticity of the dough complicating the operation of the dosing mechanisms; at the same time, the taste of the products changes (these changes are noted during the tasting assessment); their consistency becomes denser. In the process of research, the stability of the quantitative and qualitative properties of gingerbread during storage has been proved. Experimental samples of gingerbread with 25 % reduced sugar content retain all the indicators established by GOST for their storage for 90 days without statistically significant changes. The decomposition of sucralose in the manufacture of the dough is 0.1 %, in the baking process - 2.6 %, during storage for 120 days - 6.7 % (of the loaded product). The developed recipe allows enterprises to expand the range of confectionery products with reduced sugar content.