, an ammeter.
Each vertical row comprises the ammeters belonging to the feeders
which supply a given sub-station, and from left to right these are in
order sub-stations Nos. 11, 12, 13, 14, 15, 16, 17, and 18; blank
spaces are left for four additional sub-stations. Each horizontal row
comprises the ammeter belonging to feeders which are supplied through
a given group switch.
This arrangement in vertical and horizontal lines, indicating
respectively feeders to given sub-stations and feeders connected to
the several group switches, is intended to facilitate the work of the
operator. A glance down a vertical row without stopping to reach the
scales of the instruments will tell him whether the feeders are
dividing with approximate equality the load to a given sub-station.
Feeders to different sub-stations usually carry different loads and,
generally speaking, a glance along a horizontal row will convey no
information of especial importance. If, however, for any reason the
operator should desire to know the approximate aggregate load upon a
group of feeders this systematic arrangement of the instruments is of
use.
[Illustration: SWITCHBOARD FOR ALTERNATING CURRENT BLOCK SIGNAL
CIRCUITS--IN SUB-STATION]
[Illustration: EXTERIOR OF SUB-STATION NO. 18]
[Sidenote: _Alternating
Current
Distribution
to Sub-Stations
Power House
Ducts and
Cables_]
From alternators to alternator switches the 11,000 volt alternating
currents are conveyed through single conductor cables, insulated by
oil cambric, the thickness of the wall being 12/32 of an inch.
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