Electrical Power Production Systems 103
directly to the shaft of a three-phase generator, which produces the electrical
power. Water is channeled in from a higher level down into a spiral set of
blades on the turbine. The force of water flowing onto these blades causes
a rotation of the turbine in the desired direction. The water that flows past
the turbine blades is then channeled into a lower-level lake or reservoir
area. The angle of the turbine blades can be adjusted to control the speed
of rotation of the turbine. Since rotational speed must remain constant to
produce a 60-Hz frequency, the blade-angle adjustment and the amount
of water channeled onto the blades must be adjusted continuously. Also,
varying amounts of force are required to turn the turbine so that different
amounts of power are delivered by the turbine to rotate the generator. As
the load demand delivered by the generator increases, the power input to
the turbine must be increased accordingly. This control is accomplished by
adjusting the angle of the blades and the amount of water channeled into
the blades. The adjustments are automatically accomplished by servocon-
trol systems.Figure 4-14. Cutaway drawing of a hydroelectric power section at a main unit
showing equipment arrangement (Courtesy Allis-Chalmers Co.)