Niagara Falls 100.000-Hp. Development

Niagara Falls 100,000 Hp. Development [45 Upon the oil switch being opened the shaft 'is turned through an angle of 90 deg., so that the crossbar assumes a vertical position, which releases the discon- necting-switch compartment doors. Thus it is impos- sible for the operator to gain access to the disconnecting switches until the oil switch is in the open position. Provision is made for removing the crossbar by means of a special tool in case it is necessary for some special reason to gain access to the “disconnects” while the oil switch is closed. On the reserve-bus side of the disconnecting switch alley, where there are no oil switches, there is, of course, no opportunity to employ this interlocking scheme; but the six corresponding doors are fastened together in the same manner as on the main-bus side. The same scheme of operating the doors in groups is also employed on the lower floor for the compartment doors, giving access to the feeder “disconnects,” current trans- formers and cable potheads. Control.—As shown by the illustrations, the control building is placed at one end of the series of unit bays and parallel to them. On the lower or ground floor are a small office, an entrance hall, a workshop or store room, a storage- battery room and a motor- generator room, also a longitudinal passageway for control wiring. The second floor is entirely oc- cupied by the control room. The switchboards consist of vertical panels of natu- ral-finished black “Linstun” and are divided into five sections corresponding with the five main bays, in addi- tion to a house-service sec- tion. Back to back with the control boards, with a 4-ft. (1.2-m.) aisle between them, are the relay and terminal boards. A group of five panels controls each of the three bays connected with the new units—a bus- tie panel, an incoming-line panel and three fender panels, each controlling two feeders. A similar group of four panels controls each of the other two bays. A dummy bus indicates the connections. The bus-tie panel is equipped with three ammeters, a wattmeter and a reserve-bus voltmeter; the incoming-line with three am- meters, a wattmeter, power-factor meter, main-bus voltmeter, line voltmeter and synchroscope. Each of the feeders is equipped with three ammeters and a wattmeter. Each instrument and relay is provided with a complete set of calibrating link terminals mounted upon small panels on the rear of the main panels. The vertical wiring on the back of the switchboards is carried in troughs made up of two i-in. (1.9-cm.) angle sides with “Linabestos” back, the troughs being 3| in. (8.9-cm.) wide. After the wiring was completed these troughs were equipped with removable sheet- metal covers. The advantages of this system of wiring are safety, accessibility, neatness, ease of installation FIG. 63—OXIDE-FILM LIGHTNING ARRESTERS ON INCOMING LINES AT ECHOTA SUBSTATION and flexibility. Furthermore, the wires being entirely free from the panels, the latter can be easily removed, if required, by merely disconnecting the wires from the instruments and control devices. At their point of departure from the board, all con- trol wires pass through terminal links on the lower panels of the relay boards. After leaving the switch- board the control wires are carried in three-conductor cables covered with flame-proof braid and laid in steel pans or troughs mounted one above another on brackets fastened to the wall of the building. Upon reaching the point where the unit bays join the longitudinal passage- way the pan for each unit passes through an opening in the wall of the passageway and continues along the outside wall of the bay under the oil-switch gallery. From this pan to the current and potential transform- ers, oil-switch controls, etc., the control wires are carried in conduit buried in the walls and floors of the struc- ture. By this construction the control wiring is made accessible throughout its entire length, with the ex- ception of the short por- tion in conduit, and at the same time an enormous amount of conduit work is avoided. The construction is much less expensive and occupies much less space than would the conduit nec- essary to convey an equal number of wires. For the operation of the control circuits there are provided two 14-kw. motor-genera- tor sets and a 120-amp.-hr., 220-volt storage battery. The control is normally carried on one of the motor- generator sets and the bat- tery held as a reserve. Relay Protection—The incoming lines from the new generating station are each equipped with over- load, ground and reverse- power relays. The overload relays are arranged to trip both the main and reserve-bus circuit breakers, but the reverse-power relays trip only the main-bus switch. At present the reverse-power relays are Westinghouse type CR, but it is proposed to substitute for these type CW relays so connected as to operate on low power factor, lagging current feeding from the substation toward the generating station. This is for the purpose of tripping the line switch in case of the accidental loss of the field of the generator and also to enable the line switch to trip on less than full-load current in the reverse direction. The bus-tie switch is equipped with overload relays. Feeder switches are relayed in two different ways, according to the nature of the feeder supplied. In certain cases where a feeder consists of four parallel cables split-conductor protection is provided between the twé- pairs of cables by means of suitably connected current transformers and low-current relays. In other cases ground relays are installed, connected in the current-transformer neutrals. Overload relays are also installed on all feed-