12. What effects the efficiency of a reaction turbine on part-load ? Is the part load efficiency is a
function of specific speed ?
13. What are the advantages and disadvantages of very high specific speed turbine runners ?
14. What are the advantages of a high speed runner under very low heads. What are the advan-
tages of medium speed runner under the same conditions ?
15. What are the advantages of Pelton for very high heads ? What are the disadvantages of low
speed reaction turbine for the same conditions ?
16. For the same power under the head compare impulse wheels and reaction turbines with re-
spect to efficiency, speed, space occupied, freedom from breakdown, ease of repairs and
durability with silt laden water. Describe the characteristics of various types of turbines used
in hydro-electric power stations with reference to (a) head (b) part load efficiency and maxi-
mum efficiency and (c) specific speed, and, state how these factors help in the choice of the
turbine.
17. What factors are considered in selecting a prime-mover for a hydro-electric power plant ?
18. What factors are mainly considered in selecting a prime-mover for (a) run-off river plant (b)
storage plant (c) pump-storage plant.
When the supply is drawn direct from the river instead of storage reservoir, would you go in
for Pelton turbine or a reaction turbine ? State the reason for your choice. The head and flow
are same in both cases. How do the rotational speed and cavitation effect the selection of a
water turbine for hydro-electric power plants ? What are the advantages of reaction turbine
over the Pelton wheel in respect of efficiency, size, cost and maintenance ?
Chapter 12
Chapter 12
Chapter 12
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