Niagara Falls 100.000-Hp. Development

Niagara Falls 1 00,000 Hr. Development [ 37 explosions. The switch is a Westinghouse type CO-2, the choke coils also being of Westinghouse construc- tion. The static absorbers and lightning arresters were furnished by the General Electric Company, the latter being of the oxide-film type. The main leads from the generators, after passing through the current transformers for the operation of differential relays, which are located in the basement of the generating station, enter 1,250,000 circ. mil., single- conductor, varnished-cambric insulated, lead-covered cables, two for each phase, leading to the power house roof. At this point the conductors emerge from the lead-covered cables and pass out of the building through bushings and connect to open wires leading to the terminal building at the top of the cliff. The lead- covered cables are installed in slots in the concrete con- struction of the power house, and where these slots are vertical the weight of the cable is supported by cast- iron wedges inserted between the cable and the sides of the slot, which for this purpose are provided with beveled pockets at intervals of 8 ft. This method of supporting vertical runs of cable has been very success- fully used in the Hydraulic Power Company’s previous installation. The terminal building, at the top of the cliff, is con- structed with a cantilever extending out over the edge of the cliff, forming a platform, to the under side of which are attached the open wires leading up from the power house. From this point the leads enter the terminal building through bushings under the over- hanging platform. The open wiring between the power house and terminal building is supported on suspension- type strain insulators and is protected against lightning by overhead ground wires. Provision will be made for circulating low-voltage current through these ground wires in winter to prevent the accumulation of sleet. Arrangements for Control Wire Runs The control wires from the power housø apparatus are first brought to link terminals mounted upon the exciter switchboard on the power house gallery. From this point multiple-conductor control cables carry the control wires to similar terminals on the relay boards in the control building. The control wire passage, which joins the rear power house wall at the level of the roof trusses, is of concrete, built upon the sloping rock surface between the power house and the bottom of an old tailrace shaft which is used to carry the con- trol wiring up the cliff. In this control-wire passage and shaft the cables are inclosed in steel conduit, which, in the vertical portion, is clamped to a steel tower. Th:s tower is supported from the bottom and is free from the side walls of the shaft in order to protect the cables against seepage. A stone wall has been erected across the open side of this shaft, which originally was merely a slot in the vertical face of the cliff. From the top of the shaft the control wires are car- ried on steel work through existing excavation to the basement of the control building and thence to terminals upon the relay boards. An underground passage also leads to the terminal building. These passages will be utilized both for control wiring and as a subway con- necting the control and terminal buildings. Wherever the concentration of control wiring would result in congestion if placed in conduit the control wiring is carried in steel pans or troughs, arranged one above another, each pan being assigned to an individual unit. In this manner the congestion of conduit, so often seen in power plant construction, is entirely avoided, with, at the same time, a distinct gain in accessibility. Wherever necessary for protection, or where the use of the pan construction is undesirable, control wires are carried in steel conduit. Control wiring is made up in cables of seven to fifteen conductors, each conductor being covered with rubber and cotton braid, the cable being covered with flame-proof braid. No lead sheaths were used on the control cables. New Control Building for Entire Plant The control building is located upon the brink of ths cliff, overlooking the lower gorge, at a point imme- diately above the junction of the old and new generating stations, where it is most conveniently situated to con- trol both the old and new plants. The building stands directly over the discharge from the ice gates of Sta- tion 3, and use was made of some old waterways, dating from days prior to the art of electrical genera- tion, for control wire passages to the generating and terminal stations. The main generator control switchboards, which are FIG. 51-CELL CONSTRUCTION INSIDE TERMINAL BUILDING ON CLIFF ABOVE STATION A—Disconnecting- switch compartment. Observe that the com- partment doors are hinged and those in same circuit group are attached .to bar and interlocked so that when oil switches are closed the doors cannot be opened, and hence the maximum pro- tection is afforded workmen. B—Gne of the choke coils in the generator circuit. C-—Potential transformer compartment.