The main figure illustrates a typical small hydro scheme on a medium or high head. Click on the picture for a dynamic presentation of the elements of the scheme. Other possible layouts are discussed in Section 2.4.

The scheme can be summarised as follows:

• Water is taken from the river by diverting it through an intake at a weir.
• In medium or high-head installations water may first be carried horizontally to the forebay tank by a small canal or ‘leat’.
• Before descending to the turbine, the water passes through a settling tank or ‘forebay’ in which the water is slowed down sufficiently for suspended particles to settle out.
• The forebay is usually protected by a rack of metal bars (a trash rack) which filters out water-borne debris.
• A pressure pipe, or ‘penstock’, conveys the water from the forebay to the turbine, which is enclosed in the powerhouse together with the generator and control equipment.
• After leaving the turbine, the water discharges down a ‘tailrace’ canal back into the river.

Hydro-scheme components  - Click Here For Animated Version of Diagram