Vol 89, No 12 (2018)

To monitor the electromagnetic situation in different spheres of domestic service and industry under the conditions of uncertainty of frequency ranges and behavior of spatial distribution of electromagnetic field, an approach based a map showing the admissible time of in which a human being can remain in various zones of the studied space has been suggested. The map is on the basis of the results of a limited number of measurements and electromagnetic field simulations taking into account the simultaneous effect and amplification of the resulting action of several electromagnetic radiation sources. The principles of the creation of point and cylindrical pictures of electromagnetic radiation danger using the transformation of distributions of electric field, magnetic field, and energy flux density parameters have been considered. The transformation is on the basis of the systematization of approaches to determine the admissible stay time in different zones of the space under study. The structure and performance of a basic modification of integrated characterization of electromagnetic radiation danger (i.e., a technological module) have been presented. A technique that implements the suggested approach to characterization of the electromagnetic situation using the technological module has been given taking into account the possibility of a simultaneous effect of different components of the electromagnetic field.

A review and analysis of existing systems and technical facilities of local heating of facilities in the power industry and agroindustrial and housing and communal services, including those based on nanostructured multielectrode composite electric heaters, are presented. The electrophysical and physical-mechanical parameters of insulation were defined, which make it possible to use the electric heaters in corrosive media and wet conditions. A calculation methodology of antifreezing systems using nanostructured multielectrode composite electric heaters is presented using the example of heating vertical gutters. The weight coefficients of ingredients of current-conducting composite material for implementation of conditions of self-regulation of electric heater to providing its energy-efficient functioning are determined.

The fundamentals of diagnosing the technical condition of electrical plants in a real-time environment are disclosed. The key provisions of the theory of technology-related risks caused by the hazardous effect of current on people and objects in the form of accidents, electrical shocks, and fires are formulated. The concept of “integral risk” is introduced, its mathematical model developed, and a classification of risks provided. It is proposed to assess an integral risk as the product of the occurrence probability of a hazardous technology-related situation and its effect (outcome). It is supposed that the technology-related safety and efficiency of onsite electrical plants can be controlled by establishing the interaction among the components of the man–machine system, including a man (MN), electrical plant (EPL), and environment (ENV). The fundamentals of the technique of identifying and predicting risks with ambiguous information are considered, and the software implementation of this technique by logical linguistic modeling and the fuzzy logic apparatus is provided. A system approach to optimizing the integral operating risk of the MN–EPL–ENV system is formulated.

Using an asynchronous motor with a frequency converter makes it possible to provide desired operating factors of electric drive. At the same time, using known types of frequency converters of domestic and import manufacture for low-power electric drives in most cases is inadvisable due to their high cost and complicated control system, as they use pulse-width modulation (PWM). In such cases, it is possible to use converters of vector-algorithmic type, which have a low cost due to a simplified control system and a special method of arrangements of the power part and the control system of the device. When developing and testing these converters, there is an acute problem of reducing the cost for manufacturing test samples. For this reason, at the initial stage of development, it is necessary to carry out simulation using computer simulation tools. The original circuit of vector-algorithmic converter is considered in this work, and the simulation results of characteristics of the developed electric drive in the MATLAB Simulink software environment are presented. General conclusions and recommendations on using the developed vector-algorithmic converter are presented.

This article considers the current state and development prospects of the fundamentals of the electrical safety theory. The concept of electrical safety is refined. It is found out that, according to the system of labor safety standards, it coincides in content with the concept of an electrical safety assurance system. It is noted that this concept can be defined in various ways that describe electrical safety as a certain state in which human beings interact with areas of their life and activities. The list of fundamental tasks solved in the theory that has been laid out is formulated. Ten tasks are distinguished, and subtasks are distinguished in some of them. The attained solution level for each task is indicated. The current state of electrical safety theory allows setting up optimal engineering electrical safety assurance systems on particular sites and ensure the highest level of electrical safety at given costs.