Summary: This article presents the basic problems of the transmission of electricity by direct current at the end of the 19th century. It also provides important facts on the beginnings of three-phase current technology, which made it possible to organise the pioneering 175 km transmission of electricity from Lauffen to Frankfurt am Main for the International Electrotechnical Exhibition of 1891, symbolically opening the era of three-phase current in transmission technology, which continues to this day.