Niagara Falls 100.000-Hp. Development

42 j Niagara Falls 100,000 Hp. Development FIG. 50—EXTERIOR OF ECHOTA SUBSTATION, SHOWING FIVE SWITCHING BAYS AND OUTGOING OVERHEAD LINES it at right angles. In this manner the over-all length of the building was very materially reduced and the spacing between units kept down to just about that which will later be requii’ed for the step-down trans- formers, specifically 26J ft. (8 m.). The prime consideration in the general layout of this station was provision for growth. The various elements of the structure are so placed that each one is capable of almost unlimited extension without interfering with the others; that is to say, each of the power units can be extended, the number of such units can be increased, and the length of the control building which houses the switchboards can also be increased accordingly, without interference with one another. The five units or bays and the control building are connected at one end by a narrow building or passage- way which contains the incoming line protective equip- ment and serves as a distributer for the control wiring, piping, etc., and as a means of access between the con- trol building and the several unit bays. The main operating portion of the station is concentrated on the second floor, where are located the oil switches with their “disconnects” and the control room. There is little or nothing on the third floor which demands operating attention. The ground floor contains current and potential transformers and feeder disconnecting switches which require attention or manipulation but seldom. Under each of the unit bays is a subway for distribu- tion of cables. This connects at each end with longi- tudinal subways. Starting from the control room, the first two bays are intended to provide for the receiving and distribu- tion of power from station No. 3, Hydraulic plant. The other three bays are primarily for the distribution of power from the three new units, and into each of two of these bays is also connected an overhead circuit from the Niagara plant over which the flow of power is likely to be in either direction. A radical departure from the usual station construc- tion is the placing of all oil circuit breakers on the outside of the building walls; in other words, the main bus and switch structure walls are utilized as the walls of the building, all high-tension connections being upon the inside, where they are thoroughly housed and pro- tected against the elements, and the oil switches upon the outside, where explosions and oil fires can do a minimum of damage. Galleries are provided on the outside for access to the oil switches, which are pro- tected from the weather by suitable housings. As this station is a very important one in the system, serving, as it does, as the general point of concentra- tion for the output of the five contributing generating stations aggregating 400,000 hp. in capacity, great care was taken in its design to minimize to the greatest pos- sible extent the hazards inherent in the operation of such a station. To this end the different electrical ele- ments of the structure are separated and isolated to the greatest possible extent. In the first place, each unit bay is a separate building, as is also the control building. On the outside of the unit bays the oil switches are on one floor, the bus on another. On the inside the disconnecting switches for isolating oil switches are on one floor and the potheads for outgoing FIG. 57—LONGITUDINAL SECTION OF ECHOTA SUBSTATION, SHOWING TWO BAYS AND CONTROL ROOM cable feeders are on another. The main and reserve buses are completely isolated from each other. Wher- ever the connections pass through walls or floors sub- stantial porcelain bushings are used, sealed with cement compound so that there is no possibility of an arc being carried through the walls or from floor to floor. All phase connections are separated by brick and concrete barriers and are completely covered by compartment doors except where ventilation outlets are provided, so that accidental contact is virtually impossible. Arrangement of Circuits.—Each incoming line, con- sisting of two parallel circuits, passes first through dis- connecting switches, after which the two circuits are