Spinning coils of copper wire -an armature - between magnets generates electric current. The more coils there are and the faster they spin, the more current is produced by the generator. A turbine, or water-driven engine, is one of several power sources that can be used to impart the spinning motion. A pipeline, or penstock, was built along the bottom of the original dam to lead the water to
the turbines in the Folsom Powerhouse, which were set at the lowest possible elevation to wring the maximum energy possible from the falling water.
Water from the American River was diverted through the East canal to the Power- house's forbay. From there it dropped through penstocks to
drive the turbines (A)
that, in turn, powered the generators (B).
Output was regulated at the control board (C).