New-York tribune., 1901-11-17
ELETA TED r. r. SUB.STATONS
AND CONVERTING THE
CURRENT DEVELOPED AT THE
POWER HOUSES.

When the Manhattan Railway Company oper-
ates all Of its lines with electricity it expects
to have seven sub-stations to supply the neces-
sary current The buildings for three of them
are now complete, and the machinery is being
installed They Of brick four stories high,
90 feet wide and 100 feet deep One sub-station
is at Allen and Division sts-, close the point
where the Second-ave. line merges with the
Third-ave. section Another is in Thirtvfourth-
St, between Second and Third aves.. and third
is at Ninety-ninth-st- and Third-ave- These
three Will operate the two East Side lines south
of the Harlem River. Eventually there will be
three more for the West Side lines. and one for
the region north of the Harlem
The current which Is generated at the power
house of trolley road is usually of the same
kind and pressure as that which enters the
motors under the That is to say. ii is a
direct or continuous current of about $50 volts
But while direct current and almost equally
low voltage will be employed in the motors OF
the Manhattan Elevated cars the electricity
will be developed in the power house in very
different form. The dynamos there will gen.
crate an alternating current Of about 11O00
volts. The for this plan is that much
less copper is required in the cables which con-
duct high tension current than a low
But consequence of such procedure is that the
electric energy must undergo two changes be-
fore being utilized The voltage must be
duced. and the alternating current must be
altered into a direct one. 1t is the double func-
tion Of the sub-stations to perform this work
For reasons which need not be entered into
here. the generators develop what is called a
three phase" current There less than
three distinct alternating currents. whose waves
are spaced so as to overlap each other at equal
distances. Hence the CO bic which conducts the
electricity from the power house to sub-station
is made up of three separate conductors with
one wrapping. These cables. by the way. Will
through earthenware conduits ur derground-
The direct current, low tension cables which
come out of the sub-station and feed the third
rail will each contain only a single conductor
They will look like the feeders carried on poles
beside the road along which ordinary trolley
line
The apparatus by means of which the voltage
of an alternating current is raised OF lowered is
a transformer and that which changes alter
mating current into a direct one is a rotary con-
verter The latter looks like a dynamo TO an
Impractical eye. while the former wears the
characterIess exterior of big black box Each
converter in these sub-stations of the elevated
railway company will be provided with three
transformers. They will bring the voltage down
from 11.0OO 10 $50. The direct current which
ernerges from the converters into the feeders
will have voltage OF 625. Each converter Will
have normal capacity of 1000 horse power,
but can be made handle 1000 horse power IN
emergencies. Some of the sub-stations Will oe
equipped with six converters, and hence VIII %
able to supply 10000 or $4,000 at the hour Wnen
there is the greatest demand
Still another method Of meeting the extra TAX
during rush hours has been in contemplation
although there is some uncertainty about us
being adopted. At the central stations OF elsc-
tric lighting companies it is now customary 10
have an immense storage battery. which can
be charged while the demands on the dynamos
are light and which can supplement- the output
OF those machines when the demand is greatest
Thus the work Of the dynamos is rendered moro
nearly uniform throughout the twenty-lour
hours than would otherwise be possible, ana IL
Is then unnecessary TO install so much steam
and electric machinery. An economy IN ruei IS
also effected in this manner. The sub-stations
Of the Manhattan Elevated have been Designer
in such way that the two uppermost floors can
be occupied by storage batteries. while the
transformers and converters are on the two
lower To be exact 1t may De remarked
that the second floor. which carries the trans
formers and switchboards is really a gallery
opening out over the first where the converters
are situated. Each of the latter Is over thirteen
feet high. and weighs upward OF 100000 pounds