Asian Phoenix Resources POWERPAL MHG-T2 - Manual (Page 7)

When installing the penstock, try to keep it as straight as possible and avoid sharp
turns or angles. To do this, part of the hillslope may need excavating while in other
places the penstock may need supporting with poles etc. Steeper terrain has advan-
tages over more gentle terrain as cost is reduced by the use of a shorter penstock.
C
A B
The penstock is shown by the black line
A-B. In the first diagram (A) the penstock
follows the stream. This may lead to
unnecessary length and cost. In diagram
B, the most direct route is selected to
reduce length and cost. Diagram C shows
the best alternative where a side channel
or ‘power conduit’ is cut into the side of
the hill. This carries the water to a point
as close to above the turbine as possible
and best reduces the length of penstock
required.
The power conduit roughly follows the
hill’s contour and need only be a simple
ditch say 30cm x 30cm in section.
The forebay, or water holding tank at the top of the penstock is designed to contain a
water volume of at least 2.5x the volume of water in the penstock i.e. 440 litres.
Dimensions of the ideal design are shown in the system diagram although the main
point is to ensure that the forebay won’t become empty.
The top of the penstock is typically placed not at the bottom but some way up the
forebay wall so that the bottom of the forebay acts as a sink for rotting leaf litter,
deposited sand and mud etc. This sink may need periodic cleaning out. Another good
idea is to cover the end of the penstock with a piece of wire mesh (debris screen) to
keep leaves etc. from flowing in and clogging the turbine. See Appendix A for the
ideal forebay design.
PowerPal™ T2 Turgo 7