Niagara Falls 100.000-Hp. Development

Niagara Falls 1 00,000 Hp. Development [ 43 combined into one and pass through a set of choke coils for lightning protection. The “disconnects” and choke coils are installed on the third floor of the connecting passageway in brick compartments. The lightning ar- i'esters, which are connected immediately outside of the disconnecting switches, are on the roof of the passage. After leaving the choke coils the leads enter two 1,250,000-circ.-mil lead-covered cables in parallel which pass down the outer wall of the passage to the subway, thence across and up to the first floor of the unit bay. Here they emerge from the cables through potheads and connect to copper bars, which then pass through current transformers. Immediately above the current transformers are disconnecting switches above which the circuit divides, one side going through an oil circuit breaker to the main bus, the other side through a similar breaker to the unit reserve bus. In each bay- provision is made for six outgoing feeders. Each of these connects to the main bus through an oil circuit breaker and to the reserve bus through disconnecting switches. The function of the reserve bus is twofold— (1) it serves as a true reserve bus from which all feeders can be supplied temporarily through the reserve- bus switch in case it is desired to clear the main bus for any purpose; (2) the reserve-bus switch serves as a substitute switch for any individual feeder switch which may be out of service. In this manner duplication of the switching facilities is obtained without duplication of oil switches on each feeder. XjX Provision is made for the in- Static Surge \ stallation of reactors between Arres*x&/ \ bays and these will be installed I § \ as soon as they are required. | Cross - Section through Structure (Lookinq South) FIG. 58—TRANSVERSE SECTION OF ONE END OF ECHOTA SUBSTATION Oil Switches.—Owing to the great importance of this station in the general scheme of distribution, both pres- ent and future, it was determined to insure the greatest possible degree of reliability in the oil switches. Ac- cordingly both of the chief manufacturers were asked for a recommendation on this basis, resulting in the proposal of two radically different types of oil switches, namely, the Westinghouse type CO-2 and the General Electric type H-9. Owing to the absence of operating experience with these switches, it was found impossible to establish definitely the superiority of either one over the other, and it was decided so to construct the station Second Floor Plan FIG. 59—PLAN OF CONTROL ROOM AND ONE BAY AT ECHOTA that either one could be used. This was accomplished by slight modifications in the standard assembly of both types, and it was decided to install at the start a number of each type in order that actual operating experience might be had with both. The General Electric switch is assembled with the oil pots staggered and all connections brought out at the back of the switch with center-to-center spacing of 9 ft. (2.7 m.) between adjacent switches. In the case of the Westinghouse switches the same spacing of terminals was accomplished by a special design spreading the leads apart above the oil pots before passing through the wall. Thus an arrangement was arrived at whereby both of these radically different types of circuit breaker could be installed in the same width with the terminals equally spaced, so that either type of switch can in future be substituted for the other, should the type installed prove inadequate. Of the five bays, four are equipped with Westinghouse type CO-2 circuit breakers and one with General Elec- tric type H-9. Safety Features.—Objection has sometimes been made to this type of construction—in which the oil switches and their corresponding “disconnects” are placed upon opposite sides of a solid wall—that it is possible for the operator to open the wrong “discon- nects” by mistake. This error may occur in two ways—either he may select the wrong group of “dis- connects” or he may accidently get one “disconnect” on an adjacent oil switch. In this installation both of these errors have been made impossible by the follow- ing means: First, the doors covering the disconnecting switches are all hinged at one side and all six doors associated with each oil switch are fastened together by a wooden bar which is hinged to their free edges. Thus, when it is desired to obtain access to the “disconnects” asso- ciated with a circuit breaker, all of the six doors are operated together. It is therefore impossible for an operator to obtain access to a “disconnect” of an ad- jacent circuit breaker. Second, there is attached to each circuit breaker a shaft extending through the building wall carrying on its inside end a short cross-bar. When this bar is in a horizontal position it engages the edge of one of the disconnecting-switch compartment doors in such a way that the group of doors cannot be opened. This device is so connected to the oil-switch mechanism that it occupies this position when the oil switch is closed.