Power Plant Engineering

358 POWER PLANT ENGINEERING

Fig. 11.12 Fig. 11.13
Underground Power House. The conven-
tional hydro-electric power stations are usually lo-
cated over-ground at the foot of a dam or a hill slope
on the banks of a river. The first underground power
station Nerayaz was built in 1897 in Switzerland.
The high capacity underground power plants were
built only after second world war. The idea of locat-
ing powerhouse underground was suggested not only
with the intention of protecting them against air raids
but also technical and economical considerations
were mainly considered. After second world war,
the immunity against air attacks was unquestionably regarded as an important. advantage-of under-
ground power station. A large number of underground power stations have been installed in U.K., U.S.A.,
Russia, Canada, Japan after second world war and recently in India also.

In all, there are about 300 such stations in service with a total installed capacity of 31 million kW
Fig. 11.15. Horizontal setting of Pelton wheel with penstock upto the end of 1963.

Fig. 11.15

Head race Super structure

Generator

Prime

mover

Draft tube

Tail box

Screens

Head race

PenstockSteel

Primemover

Ta i l r a c e

Drafttube

Generator

Super structure

Super structure

Alternator

Tailrace

Kaplan

Tu r b i n e

Guide

Penstock vane

Draft tube

Crane

Fig. 11.14