B-STATION NO. 14]

The type H-oil switch is operated by an electric motor through the
intervention of a mechanism comprising powerful springs which open and
close the switch with great speed. This switch when opened introduces
in each of the three sides of the circuit two breaks which are in
series with each other. Each side of the circuit is separated from the
others by its location in an enclosed compartment, the walls of which
are brick and soapstone. The general construction of the switch is
illustrated by the photograph on page 94.

[Illustration: CROSS SECTION SUB-STATION NO. 14]

[Illustration: INTERIOR OF SUB-STATION NO. 11]

[Illustration: LONGITUDINAL SECTION SUB-STATION NO. 14]

Like all current-carrying parts of the switches, the bus bars are
enclosed in separate compartments. These are constructed of brick,
small doors for inspection and maintenance being provided opposite all
points where the bus bars are supported upon insulators. The
photographs on pages 95 and 96 are views of a part of the bus bar
and switch compartments.

[Illustration: TWO GROUPS OF TRANSFORMERS]

The oil switches and group bus bars are located upon the main floor
and extend along the 59th Street wall of the engine room a distance of
about 600 feet. The main bus bars are arranged in two lines of brick
compartments, which are placed below the engine-room floor. These bus
bars are arranged vertically and are placed directly beneath the rows
of oil switches located upon the main floor of the power house. Above
these rows of oil switches and the group bus bars, galleries are
constructed which extend the entire length of the power house, and
upon the first of these galleries at a point opposite the middle of
the power house are located the control board and instrument board, by
means of which the operator in charge regulates and directs the entire
output of the plant, maintaining a supply of power at all times
adequate to the demands of the transportation service.

[Illustration: MOTOR-GENERATORS AND BATTERY BOARD FOR CONTROL
CIRCUITS--SUB-STATION]

[Illustration: 1,500 K. W. ROTARY CONVERTER]

[Sidenote: _The Control
Board_]

The control board is shown in the photograph on page 97. Every
alternator switch, every selector switch, every group switch, and
every feeder switch upon the main floor is here represented by a small
switch. The small switch is connected into a control circuit which
receives its supply of energy at 110