Before the adoption of alternating current (AC), very large direct-current dynamos were the only means of power generation and distribution.
Large power generation dynamos are now rarely seen due to the almost universal use of alternating current for power distribution.
AC came to dominate due to the ability of AC to be easily transformed to and from very high voltages and the resultant low power transmission losses when power is distributed over large distances.
Sebastian Ziani de Ferranti established Ferranti, Thompson [after Alfred Thompson] and Ince in 1882 to market his Ferranti-Thomson [after Sir William Thomson] Alternator.
Ferranti went on to design the Deptford power station for the London Electric Supply Corporation in 1887 using an alternating current system.
On its completion in 1891, it supplied high-voltage AC power that was then ‘stepped-down’ for consumer use on each street.
This image is of the Ferranti 1000kW alternator (156 rpm) installed and photographed at Deptford power station in 1895.