1. Head works

2. Structure at the intake of the tunnels and flumes

3. They have Booms Trash racks Sluices for passing debris
Gates and valves for controlling the flow

4. Booms Divert ice and floating logs from intake
Consists of logs tied end to end and form a floating chain to diverts floating matter to a by-pass chute

5. Trash racks
Remove floating or submerged debris directly at the intake entrance.
Placed across the intake structure to keep out floating matter from going through the penstock.

6. They form a screen of oarallel bars welded to cross members and supported by beams
Spacing of bars varies from 1.5 to 15cm or more
Smaller the spacing greater the safety
Gates control the rate of water flow entering

10. Low pressure intake with headworks

11. High pressure or high headworks

12. Gates like Cylindrical Spherical
Butterfly of needle valves are used for water control
These gates are used at
headworks
penstocks
turbine inlets

13. Conduits Headrace Tail race Leads water from headwork to turbine
Leads water rom turbine outlet ot downstram side of plant

14. Conduits Open type Closed type flumes Canals tunnels Pipe lines
penstocks

15. Flumes
It’s an artificial water channel of wood, metal , concrete or masonry supported above the surface of the ground.
Used when its expensive to construct canals
Commonly used to cross a depression or difficult terrain

16. Usually rectangular or semi circular type
Bench flumes--- flumes that are directly supported on ground

17. Wooden flume

18. Steel flume

19. Concrete flume

20. Concrete flumes have longer life
Low maintenance cost
Wooden flumes have shorter life

21. Tunnels Water carrying tunnels Service tunnels --- dry tunnels
Diversion tunnels
To divert water away
Head race or power tunnels
Carry water to power house
These are pressure tunnels
Tail race tunnels
carry water away from the power house

22. Cross section of tunnels
Circular or horse shoe
when water flow is full tunnel acta as a pressure conduit
These tunnels are to be lined
Steel or concrete liner is necessary to prevent collapse if tunnel material is weak
During partial flow acts as open channels
No need for lining

24. Forebay
Water carried by the power canals is distriuted to various penstocks through forebay Forebay is also called head pond Water is temporarily stored in case of load rejection Water is withdrawn when load increases Acts as a regulating reservoir

25. Forebay is created at the end of the power canal by
widening it into a small basin
Constructing a small dam across the natural flow
The excess water accumulated is discharged by spillways

27. Main Parts of a typical forebay
Entrance bay or basin
Spillway
Flushing device
Screens
Valve chamber
Conduit or penstock inlet

28. Penstock Pipe connecting forebay or surge tank to turbine
Pressure conduit

29. Choice of penstock materials
Depends on
Head
Topography of terrain
Discharge to be handled

30. Materials
Steel
Rcc
Asbestos cement
Wood
Cast steel

31. Sharp bends to be avoided
They cause loss of head
Require special anchorages
Anchorage prevents penstock movement due to dynamic forces