[Sidenote: _Power
House_]
The power house is fully described elsewhere in this publication, but
it is not inappropriate to refer briefly in this place to certain
considerations governing the selection of the generating unit, and the
use of engines rather than steam turbines.
[Illustration: OIL SWITCHES--MAIN POWER STATION]
The 5,000-kilowatt generating unit was chosen because it is
practically as large a unit of the direct-connected type as can be
constructed by the engine builders unless more than two bearings be
used--an alternative deemed inadvisable by the engineers of the
company. The adoption of a smaller unit would be less economical of
floor space and would tend to produce extreme complication in so large
an installation, and, in view of the rapid changes in load which in
urban railway service of this character occur in the morning and again
late in the afternoon, would be extremely difficult to operate.
The experience of the Manhattan plant has shown, as was anticipated in
the installation of less output than this, the alternators must be put
in service at intervals of twenty minutes to meet the load upon the
station while it is rising to the maximum attained during rush hours.
After careful consideration of the possible use of steam turbines as
prime-movers to drive the alternators, the company's engineers decided
in favor of reciprocating engines. This decision was made three years
ago and, while the steam turbine since that time has made material
progress, those responsible for the decision are confirmed in their
opinion that it was wise.
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