LIGHTING SYSTEM FOR PASSENGER STATIONS AND TUNNEL
In the initial preparation of plans, and more than a year before the
accident which occurred in the subway system of Paris in August, 1903,
the engineers of the Interborough Company realized the importance of
maintaining lights in the subway independent of any temporary
interruption of the power used for lighting the cars, and, in
preparing their plans, they provided for lighting the subway
throughout its length from a source independent of the main power
supply. For this purpose three 1,250-kilowatt alternators
direct-driven by steam turbines are installed in the power house, from
which point a system of primary cables, transformers and secondary
conductors convey current to the incandescent lamps used solely to
light the subway. The alternators are of the three-phase type, making
1,200 revolutions per minute and delivering current at a frequency of
60 cycles per second at a potential of 11,000 volts. In the boiler
plant and system of steam piping installed in connection with these
turbine-driven units, provision is made for separation of the steam
supply from the general supply for the 5,000 kilowatt units and for
furnishing the steam for the turbine units through either of two
alternative lines of pipe.
The 11,000-volt primary current is conveyed through paper insulated
lead-sheathed cables to transformers, located in fireproof
compartments adjacent to the platforms of the passenger stations.
These transformers deliver current to two separate systems of
secondary wiring, one of which is supplied at a potential of 120 volts
and the other at 600 volts.
The general lighting of the passenger station platforms is effected by
incandescent lamps supplied from the 120-volt secondary wiring
circuits, while the lighting of the subway sections between adjacent
stations is accomplished by incandescent lamps connected in series
groups of five each and connected to the 600-volt lighting circuits.
Recognizing the fact that in view of the precautions taken it is
probable that interruptions of the alternating current lighting
service will be infrequent, the possibility of such interruption is
nevertheless provided for by installing upon the stairways leading to
passenger station platforms, at the ticket booths and over the tracks
in front of the platforms, a number of lamps which are connected to
the contact rail circuit. This will provide light sufficient to enable
passengers to see stairways and the edges of the station platforms in
case of temporary failure of the general lighting system.
The general illumination of the passenger stations is effected by
means of 32 c. p. incandescent lamps, placed in recessed domes in the
ceiling. These are reinforced by 14 c. p. and 32 c. p. lamps, carried
by brackets of ornate design where the construction of the station
does not conveniently permit the use of ceiling lights. The lamps are
enclosed in sand-blasted glass globes, and excellent distribution is
secured by the use of reflectors.
The illustration on page 122 is produced from a photograph of the
interior of one of the transformer cupboards and shows the transformer
in place with the end bell of the high potential cable and the primary
switchboard containing switches and enclosed fuses. The illustration
on page 123 shows one of the secondary distributing switchboards
which are located immediately behind the ticket booths, where they are
under the control of the ticket seller.
[Illustration: TRANSFORMER COMPARTMENT IN PASSENGER STATION]
In lighting the subway between passenger stations, it is desirable, on
the one hand, to provide sufficient light for track inspection and to
permit employees passing along the subway to see their way clearly and
avoid obstructions; but, on the other hand, the lighting must not be
so brilliant as to interfere with easy sight and recognition of the
red, yellow, and green signal lamps of the block signal system. It is
necessary also that the lights for general illumination be so placed
that their rays shall not fall directly upon the eyes of approaching
motormen at the head of trains nor annoy passengers who may be reading
their papers inside the cars. The conditions imposed by these
considerations are met in the four-track sections of the subway by
placing a row of incandescent lamps between the north-bound local and
express tracks and a similar row between the southbound local and
express tracks. The lamps are carried upon brackets supported upon the
iron columns of the subway structure, successive lamps in each row
being 60 feet apart. They are located a few inches above the tops of
the car windows and with reference to the direction of approaching
trains the lamps in each row are carried upon the far side of the iron
columns, by which expedient the eyes of the approaching motormen are
sufficiently protected against their direct rays.
[Sidenote: _Lighting of
the Power
House_]
For the general illumination of the engine room, clusters of Nernst
lamps are supported from the roof trusses and a row of single lamps
of the same type is carried on the lower gallery about 25 feet from
the floor. This is the first power house in America to be illuminated
by these lamps. The quality of the light is unsurpassed and the
general effect of the illumination most satisfactory and agreeable to
the eye. In addition to the Nernst lamps, 16 c. p. incandescent lamps
are placed upon the engines and along the galleries in places not
conveniently reached by the general illumination. The basement also is
lighted by incandescent lamps.
[Illustration: SECONDARY DISTRIBUTING SWITCHBOARD AT PASSENGER
STATION]
For the boiler room, a row of Nernst lamps in front of the batteries
of boilers is provided, and, in addition to these, incandescent lamps
are used in the passageways around the boilers, at gauges and at water
columns. The basement of the boiler room, the pump room, the
economizer floor, coal bunkers, and coal conveyers are lighted by
incandescent lamps, while arc lamps are used around the coal tower and
dock. The lights on the engines and those at gauge glasses and water
columns and at the pumps are supplied by direct current from the
250-volt circuits. All other incandescent lamps and the Nernst lamps
are supplied through transformers from the 60-cycle lighting system.
[Sidenote: _Emergency
Signal System
and Provision
for Cutting Off
Power from
Contact Rail_]
In the booth of each ticket seller and at every manhole along the west
side of the subway and its branches is placed a glass-covered box of
the kind generally used in large American cities for fire alarm
purposes. In case of accident in the subway which may render it
desirable to cut off power from the contact rails, this result can be
accomplished by breaking the glass front of the emergency box and
pulling the hook provided. Special emergency circuits are so arranged
that pulling the hook will instantly open all the circuit-breakers at
adjacent sub-stations through which the contact rails in the section
affected receive their supply of power. It will also instantly report
the location of the trouble, annunciator gongs being located in the
sub-stations from which power is supplied to the section, in the train
dispatchers' offices and in the office of the General Superintendent,
instantly intimating the number of the box which has been pulled.
Automatic recording devices in train dispatchers' offices and in the
office of the General Superintendent also note the number of the box
pulled.
The photograph on page 120 shows a typical fire alarm box.