Direct current is primarily sourced from DC generators such as solar panels and permanent magnet DC motors. Alternating current is generated through mechanical generators such as induction and synchronous motors. It is regarding power distribution and transmission systems. Alternating current is the preferred current for power transmission from power plants to the utilities.
Low voltage direct current transmission was developed by Thomas Edison. However, transferring high currents allows heat to build up in the transmission wires, transmission cables needed to be thicker to dissipate heat, since resistance was a big problem, So, Edison's LVDC idea ultimately failed.
Transferring smaller amounts of current at high voltages negates heat build-up while transferring more power, which makes AC essential. AC is much easier to step up and down in voltage using a transformer than DC, better used for long-distance power transmissions and high-power applications.
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