Power house arrangements and hydraulic

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POWER HOUSE ARRANGEMENTS AND HYDRAULIC 
FORCES  TRANSFERRED TO THE FOUNDATION 
General arrangement for Pelton, Francis, Kaplan- and Kaplan Bulb 
turbine power plants 
Mainly the layout of cavern Power Plants for high head turbines, but examples of Kaplan 
and Kaplan Bulb turbines are also covered : 
Inside the high head cavern power houses in Norway there are normally an expansion 
dismantling joint in front of the turbines downstream of the inlet valve so the hydraulic force 
from the valve is transferred to the pressure shaft via the penstock flange. Both vertical multi 
nozzle Pelton turbines and vertical Francis turbines are normally designed with the 
distributor or spiral case respectively, embedded in concrete.
By this design the hydraulic pressure force on the inlet cross section of each turbine is 
transferred to the rock walls in the downstream side of the powerhouse through the concrete 
which are reinforced specially towards the inlet flange of the turbine. 
In fig.1 an arrangement for vertical Pelton turbines is shown and in fig.7 detail for the inlet 
supporting collar is shown.
The arrangement of the turbines with the penstock branching pipes in an angle different 
from 90
o
on the length direction of the excavated powerhouse allows for a minimum width 
of excavation. This design also reduces the span of the overhead crane rails. This design is 
favourable specially in difficult rock where it is important to keep the width of the power 
house on a minimum
. 
In fig. 15.2 a typical underground power plant with high head Francis turbines is shown. For 
safety reason the transformers are located in a separate cavern instead of in-between the 
generators in cavern power houses for Francis turbine and Reversible pump turbine. 

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