The sun. [volume] (New York [N.Y.]) 1833-1916, 1916-03-31


obtained from the water power plants
Of the Montana Power Company at
Great Falls. Montana. 1t Is delivered
to fourteen substatiOns along the
route Of the railway. The s%ubstations
receive a 100000 volt alternating cur
rent. 1t has to be delivered to loco
motives in 1000 volt direct current.
The 100000 volt alternating current
is received through oil switches, Is
conveyed to the high tension current
distributor made up Of three lines Of
copper tubing. and there forms the
source Of power for the substatiOn.
From the current distributor the cur.
rent Is conducted through other oil
switches to the transformers. These
It enters at 100000 volts and leaves
ut 1890 volts. 1t then goes through
switches IN tho motor generator sets
and supplies the power employed to
operate them.
There are either two or three motor
generators in each substation. and
they consist of one alternating cur.
rent motor driving two direct current
generators. The motor Is Of the 90
cycle synchronous type, which means
that the current changes sixty times
each second. Each set generates n
l.5OO or 1000 volt direct current, and
the two generators, being perma-
nently connected in series, deliver a
combined direct current If 5000 volts.
This is tho highest voltage direct cur
rent used in railroad work anywhere
in the world. In ordinary street rail-
road work only $50 volts direct cur
rent is used. After It has passed
through control switches this 5000
volt direct current is conducted TO
the feeder and trolley lines. Thence
1t passes To the locomotive through
the pantacraph. the overhead contact
corresponding to the trolley pole on
the ordinary street car.
Now, most overhead trolley con
| %struction consists Of n live wire sup
ported only by cross wires strung he
tween poles on both sides Of the
track. Plainly this would not do for
mountain tracks and winter storms.
The st. Paul adopted single poles ON
one side of it's tracks. Each pole
bears n bracket. These brackets sup
port n strong steel catenary. from
which twin trolley wires arc sus'
pended Mt short intervals by hangers,
The danger Of the trolley wires break
ing and falling to earth has thus been
adequately guarded against, and the
twin trolley wire u sparkles>
collection of the heavy current at al
speeds.
The locomotives are each Of :Sl
tons weight anil cost about $l1".Ot
apiece. They will haul 5000 tor
loads trailing up a I per cent. grade
at an average speed of sixteen miles
an hour. Locomotives geared foi
greater speed haul 500 ton passenger
trains on the | PER cent. grade n
twenty-five miles an hour. ON Il le>e
stretch this speed rises to sixty mile
an hour. Where the wood burnin;
locomotive Of fifty years ago had ;
tractive power Of 5000 pounds an'
the present day Mallet steam loco
motive has II tractive power Of I6.aW
pounds; these electric monsters, II.
feet and $ inches long, have n tractiv'
power of 5000 pounds.
The valuable feature of regenera
tive braking must not he overlooked
1t may not he generally known tina
by r%egenerative braking 1t Is possible
to make the electric motor produce
power, instead of using II, or dow
grades. This produced power cal
be turned into the trolley wire Il
assist other trains and reduce TN
!, amount Of purchased electric current
4 When tho crest of u grade has bee
reached the helper locomotive |
brought to the front of the train an
coupled with the forward locomotive
both being operated as II Tn
: train Is then controlled by %reg"ncra
, tive braking rs il rolls down IN
: slope. In this way from one-quarte
to Il half of power-from - to .
i. nor cents recovered and turnc
a back into the trolley wire. where 1t !
I available for other trains t"ilinc NJ
: ward ut other points on tho road.