and so
net head 300 2.13 9.73288.14 m,
output/turbine gQH/10^6 55 MW,
total output 4 55 220 MW.
The net output of the generators is 0.9 220 198 MW. The generator
speed,N 120 f/p375 rev min^1 (acceptable synchronous speed). There-
fore the specific speed, NsNP1/2/H5/476. A Francis-type turbine is suit-
able (efficiency, specific speed, and head match this type). The turbine
setting
YsB H,
0.043(76/100)^2 0.0248,
and therefore
Ys10.3 0.0248 288 3.16 m or 203.16 m AOD.
The distributor elevation
YtYs0.025DNs0.34.
The approximate runner diameter
D4.43(Q/N)1/31.72 m.
Therefore
Yt3.160.1873.347 m or 203.35 m AOD.
The surge chamber calculations are as follows:
area of surge chamber, As28.27 m^2 ;
area of tunnel, At50.26 m^2 ;
length of tunnel, Lt4000 m.
Therefore
r(gAt/LtAs)1/20.066.
540 HYDROELECTRIC POWER DEVELOPMENT
