The Pelton wheel turbine is a
tangential flow impulse turbine. The water strikes the bucket along the tangent
of the runner. All the available energy of water is converted into kinetic
energy or velocity head by passing it through a contracting nozzle provided at
end of the p enstock. This turbine is used for high head and is named after the
American engineer Lester Pelton.
Diagram:-
CONSTRUCTION
DETAILS OF PELTON TURBINE:
Components of the Pelton turbine:-
. Penstock:- It is large sized pipeline through which the
water is provided to the turbine
runner from the dam.
- Nozzle: – the amount of water striking the vanes (buckets) of the runner is controlled by providing a spear (flow regulating arrangement) in the nozzle.
- Spear: – the spear is a conical
needle which is operated either by a hand wheel or automatically in an
axial direction depending upon the size of the unit. When the spear is
pushed forward into the nozzle the amount of water striking the runner is
reduced. On the other hand, if the spear pushed back, the amount of water
striking the runner increased.
·Runner with bucket: – Runner of Pelton wheel consists of a
circular disc on the periphery of which a number of buckets evenly spaced are
fixed.The shape of the buckets is of a double hemispherical cup or bowl. Each
bucket is divided into two symmetrical parts by a dividing wall which is known
as splitter.
- Casing: – The function of casing
is to prevent the splashing of the water and to discharge water to tail race.It
also acts as safeguard against accidents. It is made up of cast iron or fabricated
steel plate.The casing of steel plate does not perform any hydraulic
function.
- Breaking jet: – When the nozzle
is completely closed by moving the spear in the forward direction the
amount of water striking the runner reduce to zero, but the runner due to
inertia goes to revolving for a long time . To stop stop the runner in a
short time, a small nozzle is provided which directs the jet of water on
the back of vanes. This jet of water is called breaking of jet.
WORKING OF PELTON TURBINE
The amount of water striking the
vanes (buckets) of the runner is controlled by providing a spear (flow
regulating arrangement) in the nozzle.Then the efficient nozzle that converts
the hydraulic energy into a high speed jet. The turbine rotor is called runner.
The turbine rotor rotates the generators rotor and then produces electricity.
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