Direct current was supplanted by alternating current (AC) for common commercial power in the late 1880s because it was then uneconomical to transform it to the high voltages needed for long-distance transmission.

• 19世纪80年代晚期,直流电在商业电源方面被交流电(ac)所取代,因为当时要把它变换为远距离输送所需的高压电很不经济。