Free POLYTECHNIC notes on the internet for the first time by PRONAB BARUAH
Explain
hydroelectric power station.
Ans.
Hydroelectric power plant converts the
potential or kinetic energy of water into electrical energy. Hydroelectric
power plants are generally located in hilly areas where dams can be constructed easily & large water reservoirs
can be obtained. In a hydro-electric power plant, water is created by building
a dam across a river or lake. From the dam, water is led to a water turbine.
The water turbine captures the energy in the falling water & changes the
hydraulic energy into mechanical energy at the turbine shaft. The turbine
drives the alternator which converts mechanical energy into electrical energy.
The analysis of hydroelectric power generation begins with the potential
energy of the water. The gravitational potential energy ( PE ) is defined based
on a materials mass ( m ) & height ( H ) from a reference point.
PE ( potential energy ) = m.g.H
Where g is gravitational constant.
The generation of power ( P ) depends upon the period ( T ) over which water is
discharged through that height ( H ), often times referred to as the head.
P = PE/T
= m.g.H/T
The water mass may be expressed in
terms of its density( p ) and volume( v ) i.e., m = pv .
Water reservoir at higher altitudes
is a pre-requisite for hydroelectric generation. Power house is located at the
lower level. The difference in these two level is known as ‘ HEAD ` .
