The Saint Paul globe., 1900-06-03

| ators have been installed
me me generators are of two classes of
! types, we'll adapted to the work of dis
| trlput1on to be referred to later Views
| OF generators and their revolving arma-
| lures are shown
| The power, after being converted into
| eiectrlcity, is sent to the switchboard in
| the gallery, where 1t may be controlled
| and distributed:
RAPID TRANSIT CO.'S SYSTEM.
The power service is now ready. One
OF the corporations to whom propositions
were sent on the sale of the power, was
| the Twin City Rapid Transit company.
Inc Twin City Rapid Transit company
! mas an electric railway franchise. owns
and operates the entire electric railway
system of Minneapolis and St Paul The
map shows their lines running in all d.
dect1ons on the principal streets. They
have 24O miles of track in service. Their
revenue is over $2,500,OOO coming nickel
by nickel from 0000, eco passengers Their
annual car mileage is Il, 100, OG0. The max
mum number OF cars in ordinary daily
service is about 400; in maximum serY-
ice. $50.
From 1891 to 1897 they had four steam
plants with capacity of 500 horse
power, equipped with modern boilers and
engines and fairly modern generators
These plants We're distributed as shown.
By consolidation into one large power
station, many savings due to the cheap
water power, decreased labor repair ex
penses and distribution losses were ap-
parent
l. "A IorIV-year tease or all the power
produced by the dam was effected by
the railway company about Jan /, 1897
The choice of generating machinery.
transmission and distribution plans and
! equipment was left to the railway COM
DanY
! Without detailing the investigations
made by the company we can say briefly
| that exhaustive study was made Of the
most modern electric plants III the cOun-
try. of most improved methods of trans
mitting and distributing large blocks of
power over long distances.
Given 10.000-horse power at the dam
the problem was to convert this power
into electrical energy and distribute it
to 800 cars scattered over two cities
About sixty of the heavier cars were
within a mile of the station. The genera
/ ton and transmission of 2,000-h horse power
for these sixty cars was planned and car
! ried out by using low voltage direct cur
! rent. This low voltage. 600 volts. is adapt
| ed only for short tranSmiSsiOnS. 1t was
! necessary to send 3009-horse power to
| No. / steam station. now known as a sub
! station. The distance from the water
power station to this substatiOn is ONE
| and a half miles. For this transmission
! it was necessary to employ alternating
! currents and to use a pressure six times
as high as that used by the short and
ordinary transmission Just referred to.
Alternating current apparatus is neceS-
! sary for economical and structural rea-
sons when we will transmit large blocks
| of power over long distances. High pres
sures are necessary In order to reduce the
| decrease transmission losses.
| The two transmissions to St Paul We're
especially long, seven and nine miles 1t
! was necessary to use 1900 volts, an eX-
! traordinarily high pressure, in order that
the cost OF cables and the losses IN trans
mission might be reduced. Twelve thou
sand volts was the highest pressure here
| tofore carried for heavy power distrtbu-
| ton in UNDERGROUND cables, and many
were the propheSies of failure. One ca
| Bile, two inches in diameter was used for
! eapb Cgn horse mower transmitted. Each
! ca bic contains three wires, each A inch
| in diameter, separated and insulated from
common manila paper impregnated with
| resin OIL linSeed oil and other insulating
| compounds. The cable is drawn in ce
inert conduit ducts three inches in diam
| eter These ducts are protected by con-
| crete and arc laid about three feet below
/ the road bed. Manholes are located
every 500 feet for the purpose Of drawing
| the cables in the duct, making cable
| spices and for inspection and repairs.
| Reviewing the complete cycle, let US
| start over again with the water which
| formerly tUmbied down the rapids below
st. Anthony falls. 1t has been damned,
| a pond formed and a fall of eighteen feet
! produced. The falling water. in passing
! through the turbines, developes 10001
! horse power which is converted into cleo
| trio rower by the generator attached to
| the turbine. Direct current Of low pres
sure is provided by two of the Loco horse
| power generators, while alternating cur
rent of moderately high pressure is gerer-
ated by the remaining eight generators.
! All the electric power is first carried to
! switch board in the gallery. The Cper-
! ating electrician can start the generation
| of current, vary the amount and read
/ from the meters the amount developed.
! Ry means OF switches varying amounts
| are sent to the different substations to
/ meet the changing conditions of load and
| service. The low voltage direct currents
are sent to the nearer lines. especially for
the heavy interurban service. Medium
| pressure alternating currents, a. $500
! volts, are sent to the Minneapolis sub
stations. and the extremely high pres
! SureS, 12.ee0 volts, are sent to the st. Paul
! SubStationS.
1t may be interesting to state that the
! transmission of 1900 horse power over
| nine miles to the farther st. Paul sub
station, at 12,G00 volts pressure, is accom-
| plished with cable loss of but per cent
| of the power SO transmitted.
! At the sub-station the alternating cur
! rent is reduced in pressure and convert
ed into direct current, after which the
! sub-station operator sends the power
! through his local distributing switch
| board.
An attendant is required to supervise
the Transforming and converting appara-
! tus at the sub-station and to care for
| the low tension railway distributing
! the power from these sWttchboards TO
! the different trolley sections. Over
| Loo pounds OF copper are, required for
! these local distributions. The current at
| the car is under the control Of the mot
orman, who uses it for the motors on
the trucks beneath the cars.
In this railway system there are three
| interurban lines; the longest, % miles
/ long, between ST Paul and Saltwater,
has on the car equipment air brakes. air
whistles and are lamp Headlights It
makes A miles per hour, maximum
| speed; has a schedule of Y miles per
hour. Each car has a telephone used for
| desPatching cars. Long 10 per cent
| grades are mounted. All interurban cars
| are double-truek Al feet long, weigh from
| is to 22 tons, and seat 81 passengers
The efficiency of the whole power sys-
tenn is very low. There is a 5 per cent