226 THE MARINE TERMINAL OF THE GRAND TRUNK 
ELECTRICAL EQUIPMENT. 
As previously explained, the group of pumps on each side of each sec- 
tion of the dock will be operated through horizontal and vertical shafting 
by one electric motor. Thus, for the two smaller sections of three pontoons 
each there will be required four 100 horse-power motors and for the larger 
section of six pontoons there will be required two 200 horse-power motors. 
The motors are to be alternating current, 3-phase, 25-cycle, 550 volt, and 
will operate at approximately 500 revolutions per minute. They are to 
have wound rotors and slip rings for variable speed control. The armature 
shaft is to be extended on both ends and will operate the distribution shafts 
through reduction gearing at a speed of approximately 275 revolutions per 
minute. 
Referring to Plate 115, there will be seen diagrammatically the location, 
arrangement and connections of these motors. There will be two motors 
on each section, one on each wing. The power circuit on the pier is con- 
nected to the power circuits on the sections by flexible cables. The power 
circuits of each section are independent from the main circuit, so that each 
section receives its power independently, but the control system is to be so 
arranged that the two motors on any section may be operated from one 
master panel or the combination of any two sections may be operated from 
the master panel on either of the two sections, and lastly, when all three 
sections are used together, all six motors are to be controlled from the master 
panel on the middle or larger section. 
MASTER PANEL. 
The master panel is to consist of a panel or drum having suitable con- 
tacts or switches for independently starting or stopping any of the motors. 
The starting or stopping of any one motor or a number of motors will not 
affect other motors at rest or in operation. ‘The provision is also to be made 
for operating any or all motors at one-half, three-quarters and full speed. 
COMPRESSED-AIR EQUIPMENT. 
While steam-driven air compressors are provided in the power plant 
to furnish compressed air for the shops, it was deemed advisable on account 
of difficulty due to the extreme rise and fall of tide, to make flexible air con- 
nections to the floating dry-dock and to provide an electrically-driven air 
compressor upon each section, 
