pressure relief valves; surge tanks; turbine governors; generators; the
power house superstructure; cranes; a switπch yard for transformers and
switching equipment; transmission lines. The only accessories briefly
described here are those that are of direct concern to the civil engineer;
dams, control works, intakes, fish passes, canals, gates and valves are dis-
cussed in previous chapters.
For more detailed information of the components of hydropower
plants including economic analyses see e.g. Mosonyi (1987), Gulliver and
Arndt (1991), or Zipparo and Hasen (1993).
12.9.1 Head race
The head race is a conveyance for water from the source (reservoir or
river) to the power plant in the form of a canal (open waterway), tunnel
(low-pressure conveyance) or penstock (high-pressure conveyance) (Fig.
12.5). The open waterway usually terminates in a forebay which is an
enlarged body of water from which the penstocks convey the water to the
turbines in the power house.
518 HYDROELECTRIC POWER DEVELOPMENT
Fig. 12.17 Recommended dimensions of an elbow-type draft tube
(Mosonyi, 1988)
