high-voltage power line високовольтна лінія електропередачі кабельні системи електрообігріву підлог роботи без зняття напруги 504.06 537.85 621.315 active shielding of the magnetic field assessment of compliance with the normative level built-in substation built-in transformer substations cable electric heating system of the floors calculation method current conductor electric heating cable systems of the floors external magnetic field high-voltage overhead power line live-line maintenance living space magnetic field magnetic field near wires magnetic field of a group of electricity networks modeling and measurement multi-dipole mode reducing the magnetic field residential building residential premises urban transformer substation work on wires without removing the voltage активное экранирование магнитного поля