Determination of the conductor resistance during their explosion in vacuum under conditions of skinning the current

The work is devoted to the investigation of the features of the conductor explosion in a vacuum under the conditions of skinning the current, and specifically, the effect of the magnetic field nonlinear diffusion wave spreading over the exploded conductor on its electrical properties. Experiments on the explosion of conductors were carried out on the IMRI-5 pulse power generator. The exploded conductor was soldered to the cathode and mechanically clamped between the plates on the anode. In the experiments, we used two types of conductors, cylindrical and flat (foils). Cylindrical conductors were of two types: copper (0.5 mm in diameter) and aluminum (0.44 mm in diameter). Foils were also of two types: copper with a thickness of 300 microns and aluminum with a thickness of 200 microns. The foil width varied from 1 to 3 mm. The length always remained 30 mm. To calculate the circuit inductance and calculate the corrections for the real conductor inductance, we used a load that was either a copper foil 600 μm thick and 1 cm wide, or a copper conductor with a diameter of 2 mm (short circuit mode).

Development of Drone Mounted BLDC Motor Stator using Multi Stacked Structure of Cartridge

Received:11 november 2020; Accepted: 27 December 2020; Published online: 05 April 2021 Abstract: Drones are used in agriculture and external control, utilizing cameras, various sensors, and autonomous flight functions. However, it is difficult to fly for a long time because of flying with heavy equipment. Therefore, it is necessary to increase the flight time through lightening of the drone itself and efficient control of the BLDC motor. That is, it is necessary to improve the motor itself, which accounts for most of the energy consumption in drone flight. Stator fabrication of existing BLDC motors is done by winding copper wires through individual processes on the stator core through an automated process. However, in the case of an ultra-small BLDC motor, the stator core has a small size and is manufactured using a thin-diameter copper conductor, and thus has a lot of problems in the automation process. Therefore, in this paper, the multi-division coupling structure method of individual teeth of the stator was applied through a new type of BLDC motor stator design. That is, the cartridge type BLDC motor stator was applied to improve and reduce the BLDC motor stator method. Through this, the performance limit of the BLDC motor was improved by combining individual teeth with multiple cartridges. The cartridge type BLDC motor is manufactured by stacking several cartridges on each tooth. Therefore, various performances can be produced according to the connection state of the cartridges

On specific short circuit parameters of 12 vautomobile electric systems

Introduction. The data presented in the article show that the problem of differentiating primary and secondary short circuits is very important. The purpose of the article is to develop a scientifically grounded research method for copper conductors of automobile electric systems showing signs of a short circuit to identify the cause of its damage in a fire investigation. Materials and methods. The research was conducted with the help of JSM-6390LV scanning electron microscope having an energy dispersive microanalysis unit attached, DuraScan 20 microhardness tester, and Fluke Ti400 infrared thermal imager. Results and discussion. It is experimentally proven that the microhardness of a copper conductor subjected to a primary short circuit differs from that of a copper conductor subjected to an overcurrent or external high temperature. Images of microhardness measurement areas of a copper conductor subjected to a primary short circuit are provided. The results of an energy dispersive analysis and characteristic diagnostic features allowing to establish the cause of the copper conductor damage in case of fire (primary or secondary short circuit) are provided. The temperature of the copper conductor is measured for short circuits that entail sparking and an arc. The applicability of the computational method for determining the conductor temperature in the event of a short circuit is experimentally proved. Conclusions. A differentiation method is proposed for telling primary short circuits from secondary ones arising in copper conductors of automobile electrical systems. It is shown that the microhardness testing method can supplement the scanning electron microscopy method. The results provided in the article can be used by specialists to study copper conductors extracted from burned vehicles in order to identify the mechanism of their damage and, eventually, the cause of the car fire.

Неупругое растяжение медного однопроволочного проводника при неограниченных местных деформациях и положительной температуре

Results of experimental and desktop studies of the single-wire copper conductor deformation under the overcurrent action are given in the article. The conductor was studied using the JSM-6390L reflection electron microscope. A mathematical model of the stress-strain state of the copper bar in tension and under a temperature below 700 °С has been developed on the basis of the classical nonlinear problem of the structural mechanics. The mechanical forces in a single-wire copper conductor, which cause neck formation during overcurrent flow, have been determined. The mathematical model has been simplified to simple analytical dependences providing their use in forensic fire and technical investigations.

Solving the problem of exploitation of transformers with corrosive sulfur by oil desulfurization using a strong inorganic base and organic solvent

Most power transformer failures are associated with the presence of corrosive sulfur compounds in mineral insulating oil, of which dibenzyl disulfide (DBDS) is the best known and most widespread corrosive sulfur compound. The oil of failed transformers usually contained DBDS, a compound with a pronounced affinity for the formation of copper (I) sulfide (Cu2S). Copper (I) sulfide is a compound that does not dissolve in oil, conducts electricity, and can be deposited on the paper insulation or copper conductor of the transformer. Created conductive paths between the windings can initiate turn-to-turn breakdown and failure of the transformer. Several technological procedures have been developed as a solution to oil corrosivity. The application of desulfurization technology developed by the Electrical Engineering Institute "Nikola Tesla" enables the efficient removal of DBDS and aging products from mineral insulation oils.