Hydro - Electric Power Plant

• Hydro - electric power plant utilize the potential energy of water to move hydraulic turbines which are coupled to electric generators. Therefore, these plants have to be located where the water resources are available in abundance at sufficient head.
• The first hydro power plant was set up in 1897 at Darjeeling of 200KW capacity and the first major hydro-power plant was commissioned in 1902 of 4.5MW capicity of Sivasamudram scheme in Mysore. 
• A large amount of water is collected during rainy season in a reservoir will not be able to meet the maximum load, therefore, the present trend is to use hydro-electric power plant with steam power plant in an interconnected system. 

The main components of the hydro-electric power plant and their function are as follows:

1. (Reservoir) : A reservoir is provided to store water during rainy season and supplies the same    in dry season. The water from the reservoir is used to run hydraulic turbine.
2. (Dam) : A dam is structure of considerable height built across the river. Its function is to provide working head of water for power plant and to increase the storage-capacity of reservoir.
3. (Trash rack) : These are made up of steel bars. Trash rack is provided to prevent entry of debris into the intakes from dam or from the forebay. Any debris into the intake water pipe may damage the turbine runners or choke the nozzles of an impulse turbine.
4. (Gate) : The gate is provide for controlling of flow of water from reservoir to hydraulic turbine through penstock. It is closed when maintenance of system is required.
5. (Waterway and Penstock) : A waterway is used to carry water from the dam to the power house. It include canal and penstock or a tunnel. The penstock are made up of steel of reinforced concrete which are designed to withstand high pressures. penstock are supported by Anchors. Sharp bends in penstock are avoided in order to reduce hydraulic losses.
6. (Power house) : A power house consists of hydraulic and electric equipment's where the water energy is converted into electrical energy. usually the power house is located underground whenever possible e.g as in case of Koyana power house in Maharashtra stare.
7. (Hydraulic turbines) : These are used to convert the kinetic energy of water into mechanical energy.
8. (Spillway) : A spillway is provided to discharge the flood water and to keep the level of water below the disigned maximum level in the reservoir. Thus a spillway saves the dam from damage during floo