Calculation of the magnetic field of a low-voltage busbars of a built-in transformer substation

The purpose of the work is to develop an analytical method for calculating the magnetic field near a low-voltage busbars of a 6(10)/0.4 kV transformer substation built into a residential building of an old building, which has no restrictions on the distance to the calculation zone. Using the Bio-Savar’s law and the principle of superposition, a mathematical model of the magnetic field of individual straight sections of the busbars has been constructed and an analytical method for calculating the magnetic field of a low-voltage busbars of a transformer substation has been developed, determining the induction of its magnetic field as a whole. The developed method for calculating the magnetic field has been verified, by means of experimental studies on the magnetic measuring stand of the institute of a full-scale laboratory model of a low-voltage busbars of a transformer substation with a power of 100 kVA, that confirmed the coincidence of the calculation results and the experiment with a spread of no more than 5 %. The character of the distribution of the magnetic field over a three-phase low-voltage busbars was determined, which is close to a dipole, which determines the possibility of its effective reduction by simpler active shielding systems with one compensation winding. Wide application of the developed methodology is planned in the creation of new methods and reduction means the magnetic field level of existing built-in transformer substations 6(10)/0.4 kV with a power of 100–1260 kVA to a level that is safe for the population.