Gramme ring dynamo

Small gramme dynamo, around 1878
Zenobe gramme reinvented Pacinotti's design in 1871 when designing the first commercial power plants, which operated in Paris in the 1870s. Another advantage of Gramme's design was a better path for the magnetic flux, by filling the space occupied by the magnetic field with heavy iron cores and minimizing the air gaps between the stationary and rotating parts. The gramme dynamo was the first machine to generate commercial quantities of power for