The dissertation is devoted to the actual scientific and practical task of normalization of the electromagnetic environment of the working zone at the testing sites of electric machines of electrical repair enterprises.
Modern production is characterized by a dense location of electrotechnical equipment, which polluted the space of the industrial environment with electromagnetic fields of industrial frequency. The greatest attention is paid to electric motors. First, this is due to their prevalence and location at the workplace, and secondly, they are one of the main sources of electromagnetic radiation in the workplace. In the process of motor operation, the level of the fields may vary and exceed the normalized performance. Studies of the last 50 years show that prolonged stay of workers under the influence of excessive indices of magnetic field induction leads to an increased risk of oncological diseases due to impaired functioning of cells and organs of a person. Therefore, the actual task is to consider and apply protection measures against over-norm indicators of magnetic fields in the production environment.
To solve this problem, the research has been carried out on the real equipment. Taking into account the maximum value of the magnetic field induction value B = 0.2 microTl for the maximum permissible level, it is established that the safe distance for low power motors is up to 0,65 m, and for high power motors - more than 2 m. As a result, an analytical dependence was obtained between the effect of the magnetic field induction of the power of the asynchronous motor and the distance to it.
Due to the fact that the electrical equipment in real conditions situated very densely, a laboratory-research bench using a computer-measuring complex was developed. The mentioned equipment allowed to determine the influenced value of the induction magnetic field during different power frequencies and the mode of operation of the asynchronous motor. It is established that during the change in the load on the shaft on the clamps of the asynchronous motor and the FC the magnitude of the induction magnetic field increases by more than 2 times, which is due to the increase of switching currents, and for a regulated electric drive with an increase in the frequency of the supply voltage from 30 to 50 Hz values the induction of the magnetic field increases by an average of 2,8 times.
During the research, it was found that the value of induction magnetic field affects the operating time, namely, prolonged use of electric machines leads to an increase in the dangerous distance around them. Solving this problem requires consideration of the energy processes occurring in asynchronous motors. Therefore, a method was developed for determining the electromagnetic parameters of asynchronous motors and power consumption.
The performed calculations showed that the power consumption varies within 10-15%, which leads to a change in the pattern of the propagation of magnetic field induction around the asynchronous motor. Therefore, the use of protective screens was proposed, which allowed to obtain a database for mathematical planning of the experiment under the scheme of rotatable central composite planning. The received magnetic field distribution model takes into account the power, the distance to the asynchronous motor and the coefficient of screening of the protective screen, and it is an effective tool for determining the measures for protecting workers from the dangerous effects of electromagnetic fields. It has been determined that the use of screens of grid structure allowed to reduce the level of magnetic field around working asynchronous motors by 55% and, thus, reduce the safe distance to the workplace from 25 to 45% depending on the power. Based on the calculations, an algorithm was developed for selecting the measures and means for mapping and predicting the propagation of the magnetic field induction from asynchronous motors.
