The San Francisco call., 1910-01-16
HARNESS FOR THE
MOUNTAIN STREAMS
Great Progress Made in Recent
Years in Science of Hy-
drauIic Engineering
peItOn=Francis Water Wheel
Meets All Requirements of
Modern Power Plants

An important part OF san Franciscoss
manufacturing industry is the design
ing and building OF water wheels for
mining, and especially for hydro
electric power plants. With the har-
Messing Of western streams for the
generation Of electricity California has
felt the cali for proper machinery. and
in the Pelton impulse water wheel en-
gineers have found a product that
answers the need of water wheels for
both high and low pressure plants.
This wheel was invented some 25
years ago. since which time it has been
almost exclusively manufactured in
san Francisco. and some time ago the
Peiton water wheel company perfected
a turbine water wheel which answers
The needs Of present day power de-
velopment
IMPULSE WATER WHEEL
The impulse or tangential water
wheel is particularly suitable for
operating under high pressures, say
from 200 to 5000 Gradually the high
pressure power sites have been taken
10 and improved by the various power
and transmission companies through
cut the Pacific slope. Huge plants with
their transmission lines, fumes and
power houses involving millions of dol
lars of expenditure are operating
throughout the mountainous sections of
the western portion of the United
states These so called high pressure
power sites being the most favorable
were naturally first improved by the
power companies.
Ia tlIe last few years, however, as
the demand for q cheap power has in
creased. il became necessary to seek
more unfav0rsble locations for the
1ydIsD- electric plant. that is, those in
vOlvins q lower water fail and more
costly as TO Development To meet
these conditions the Pelton water wheel
company OF san Francisco designed and
placed on the market a turbine water
wheel particularly adapted for operat-
ing under pressures from 40 to 500 and
to handle large volumes of water.
Pelton-Francis turbines, representing
s they do me first water wheels OF this
type 10 be built in San Francisco. and
The western portion of the United
states as far as that is concerned,
possess points of special interest to the
engineering public because Of their
unique design high efficiency and
susceptihility OF the closest possible
speed regulation-so eminentIy neces-
Sarv ia hydrO-electric plants feeding
long distance high tension transmits
sion lines.
PELTO&-FRANCIS TURBINE
The accompanying illustration shows
"a Pelto1-Francis turbine with the side
plate removed. The speed governor and
relief valve are also shown in place.
Turbines Of this general design have
been built IN the San Francisco shops
II the Pelton company up to 5000
horsepower capacity per unit
In general the machine consists of
runner provided with curved blades
and upon which the water impinges.
causing rotary motion. This runner is
keyed 10 shaft which in turn is di-
rectly connected TO electric alternators.
The flow Of the water is controlled pri-
marily by a large gatevalve which is
operated. however. only when the ne
cessity arises for completely shutting z
on the flow of water TO the runner
Speed regulation is accomplished by
the Pelton oil pressure governor shown
in the cut actuating bronze wicket
gates series OF the latter are sit
uated inside of the turbine casing. and
their movement usually through very
small arc, regulates the flow OF water
TO the turbine runner TO suit the load
requirements.
RELIEF MECHANISM
A heavy cast iron casing. spiral in
form. inclOses the runner and wicket
gates. This is made spiral TO impart
a constant velocity OF the water as il
enters the guide vanes, which in turn
direct Il upon the curved blades Of the
% a~a ha rnrfnIr
mechanically connected TO a gate ring
which, in turn, is automatically ad-
Justed by the speed governor when the
load comes on and of. Since this form
Of gate mechanism is distinctly a water
throttler, it follows that in long pipe
lines which lead the water from the
forebay 10 the turbine a tremendous
pressure increase would be caused
should the governor suddenly close the
turbine gates. An abnormal pressure
rise would tend TO burst the pipe line
were the pressure not regulated by
some suitable relief mechanism.
IN the case Of Pelton- Francis tur-
bines this Is accomplished by special
relief valve shown in the picture at
tached 10 the lower portion of the tur-
bine with the pipe leading down into
The tsilrace- The operation of this re-
lief valve-like the wicket gates of the
turbines primarily controlled by the
speed governor.
In the case Of turbine unit carving
say load Of 5000 horsepower, and this
amount is instantly thrown off. due TO
the circuit breakers in the power sta
tion going out, OF for any cause what
soever. the governor within a few sec
onds Of time would instantly close the
turbine gates, thus arresting the ire
mendous volume Of water in the pipe.
amounting in many instances to thou
sands OF tons.
SAFEGUARD FOR PIPE
The energy thus produced should be
speedily controlled 10 safeguard the
pipe from bursting The desired result
is obtained as follows:
Immediately upon the governor start
ing 10 close the wicket gates due 10 =
drop Of the load, the relief valve com
meRces to open, which operation is
continued until the increased pressure
rise in the pipe has been restored to
normal Upon this being accom-
plisheo, the relief valve slowly closes.
so as 10 effect water economy. An oil
bypassing device causes the closing
movement
In ordinary spring or hydraulicaIlv
balanced relief valves, their movements
are dependent upon rise of press
ure in the pipe, and often they fail
to operate at a critical time because
OF this feature of their design with
the Pelton mechanically operated re-
feF 1va "a oNe~ofiov,