Electromagnetic induction and eddy current effect: When alternating current passes through a single-core cable, an alternating magnetic field is generated around the cable. If this cable passes through a steel pipe, since the steel pipe is a conductor, the alternating magnetic field will generate electromagnetic induction inside the steel pipe, and then eddy currents will be produced in the steel pipe. Eddy currents are generated by Den cirkulära rörelsen av fria elektroner i ett stålrör under påverkan av ett magnetfält . Denna process förbrukar elektrisk energi och får stålröret att värma upp . Om det finns överdriven värme kan det orsaka säkerhetsproblem som bränder .
Magnetic fields with opposite current directions cancel each other out: If multiple cables in the same circuit (such as three phase lines and one neutral line in a three-phase four-wire system) are run through the pipe together, due to their opposite current directions, the generated magnetic fields will cancel each other out, and thus no significant eddy currents will be produced inside the steel pipe. However, since single-core cables have only one conductor, the magnetic field De genererar kan inte avbrytas av andra ledare, så virvelströmeffekten kommer att vara mer uppenbar .
