Magnetic field normalization in residential premises located above built-in transformer substations 6(10)/0,4 kV power 100-400 kVA

The purpose of the work is to define methods and means of screening, sufficient to reduce to a safe level the low frequency magnetic field in residential premises of old buildings, located above built-in transformer substations 6(10)/0,4 kV power 100–400 kVA at short distances to the premises. To achieve this goal, a modified method for synthesizing active shielding systems of the magnetic field for transformer substations at short distances from the substation to the floor of the premises, and its experimental verification was carried out on a full-scale physical model of a transformer substation power 100 kVA with a physical layout of the synthesized active shielding system. A synthesis of active shielding systems of magnetic field for transformer substations with a power of 100–400 kVA at short distances from the substation to the floor of the premises and an analysis of their effectiveness were carried out. It was determined that the normalization of the magnetic field on the floor surface for transformer substations with a power of 100 kVA using a synthesized active shielding system with one compensation winding is possible at distances of at least 1,15 m from the substation, and with two windings - at least 1,02 m. It was determined that normalization of the magnetic field on the floor surface for 400 kVA transformer substations using a synthesized active shielding system with two windings is possible only at a distance from the substation of at least 1,6 m. An analysis of the effectiveness of the combined use of active and passive shielding was conducted. It was determined that the combined use of synthesized two-channel active shielding systems and a passive flat electromagnetic shield made of 4 mm thick aluminum sheet allows reducing the magnetic field above the built-in transformer substation with a power of 100 to 400 kVA to the normative level while limiting the distance from the substation to the floor of the premises to at least 1,08 m and provides protection of public health from the effects of the low frequency magnetic field.