The Black Hills union. [volume] (Rapid City, Pennington County, Dakota [S.D.]) 1889-1904, 1895-09-06
MINING MATTERS
THE slLvERroN ELECTRIC
PLANT.
Successful Long Distance mission o.
Power.

Power.
An important application of the three
phase system of long-distance trans
mission of power has recently been in
stalled and put in operation ut the Sill
yer Lake mines, Silverton, Colo
RADIO. where power is transmitted a dis
lance of three miles through some OF
the toughest country in Colorado. 1t
is attracting considerable attention
among mining men. as it is the first
H,ree-phase plant installed in the Rocky
g Aantain region. says the Mining In
q KY and Review.
The success of direct current trans
mission has been thoroughly demon
strated by transmission plants operating
not only IN Colorado but elsewhere all
over the world The expense, however,
~inseparable from direct current trans
mission, precludes the utilization of that
system IN most places. where the dis
lance exceeds a certain limited number
of feet. This will be readily understood
when it is stated that If 100 horse power
can be transmitted by direct current
one mile at 500 volts. 10 per cent being
allowed for loss in the line, the copper
wire necessary will cost about $1,000.
While for the same horse power trans
mitted by the same system for ten miles
it will cost about 100000. If, however,
the tlree-phase current at 5000 volts
be employed to. transmit the 1O0-horse
power ten miles. the cost will not be
more than $1,000. In other words. a
given horse power can be transmitted
by the three-phase system at 5000
volts, ten times farther than a similar
horse power by the direct current sys-
tenn at 800 volts for the same expendi-
tnre in copper. AS. therefore, the QueS-
ito of dollars and cents is most promi-
nent in all transmission installations.
the three-pflase system. where long dis
lance transmission is concerned. is the
most practical system because the mos,
economical. commercially speaking. and
b installation at Silyerton is a strik-
ing example Of this fact
The Silver Lake group OF mines lies
about four miles southeast Of SilvertOn,
and is situated at an altitude Of 1900
feet above sea level. They are owned
by Edward G. Stoibe-. The ore mined
carries both gold and silver, is of a
comparatively low grade and requires
concentration.
Previous to the installation of electri-
city, the mill, which is situated on the
shores OF the lake, near the mouth of
the mine tunnel, was run by steam.
Coal was brought to the steam engine
by the zigzag path up the mountain.
and by the time it reached the furnace
cost $S.75 a ton. This represented a
monthly expenditure of almost a thou
sand dollars. and the expense proved 4
burden which went far to eat up profits
of the mine. Reform, therefore, be-
came imperative.
The plant is now operated by water
power, which is brought from the Ami
mas river. above Silverton, through a
3x4-foot fume $3.50 feet in length.
which carries 1850 cubic feet OF water
per minute. One of the great advant-
ages of electrical utilization is here dem
OnStrated, for it was found less expen-
sive to build this costly two-mile fume,
running from above Silverton down to a
spot where the necessary head could
be utilized, ard then to transmit the
electricity back to the mine. rather
than to continue to burn coal at the
price which it brought at the mouth of
the Silver Lake mines.
The head of water obtained is about
$50 feet; this develops on the water
wheel shaft G40-horse power. The plant
consists of two four-foot, double nozzle
Pelton water wheels, wheels with spe-
cial buckets belt connected to two $50
Il. w. 200-horse power General Elec-
lic three-phase generators.
The current from these machines is
given u at $500 volts and is transmit
ted over a distance of a little more
than three miles to the Silver Lake
mill and mine.
The conductors are No. 3 3 & S bare
copper wires, one fer each branch Of the
three-phase circuits. These are strung
from the power house, up the mountain
passes and through the rugged. forbid
ding country. In one place. where a
chasm has to be spanned, the wires
leap from pok. to pole a distance Of 275
feet. They have been strung with es-
pecial care as beftted the abnormal
conditions. At each jnsulator the wire
is run through a short piece of rubber
u b as an extra %precaution against
leakage. Lightning arresters are placed
at each end Of the line, and an addi-
+ional safeguard against possible dam
i. e by lightning is provided in the
sSIape Of a barbed iron wire, which ex-
DIS the entire distance Of the line
an the tops Of the poles, and is
81 sti5aass at every second pole. In this
.Safffry, where the storms are frequent,
and the Lightning disastrous in It's eff
fects, every precaution is taken to frus-
trate pSRsible damage from atmospheric
dischara 5. The most effective light
ming aotssters which have been found
for thisN are those which the Gen
cral Electric company itself manufac-
lures, although every other kind has