Another type of electromechanical regulator is the
carbon-pile device. This type of regulator is used
in generator systems with outputs in excess of 50 A
and provides smoother regulation compared with the
vibrating contact regulator. Carbon-pile regulators
consists of a variable resistance in series with the
generator’s shunt wound fi eld coil. The variable resistance
is achieved with a stack (or pile) of carbon discs
(washers). These are retained by a ceramic rube that
keeps the discs aligned.