A panel located near the center of the board between alternator panels
and feeder panels carries standard instruments used for convenient
calibration of the alternator and feeder instruments. Provision is
made on the back of the board for convenient connection of the
standard instruments in series with the instruments to be compared.
The panel which carries the standard instruments also carries ammeters
used to measure current to auxiliary circuits in the power house.

For the feeder board, instruments of the round dial pattern are used,
and for each feeder a single instrument is provided, viz., 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. These
conductors are installed in vitrified clay ducts. From dynamo switches
to bus bars and from bus bars to group and feeder switches, vulcanized
rubber insulation containing 30 per cent. pure Para rubber is
employed. The thickness of insulating wall is 9/32 of an inch and the
conductor