Patent GB-190700634-A (GB)
Title: Improvements in and relating to Electric Distribution Systems
Filed: 1907-01-09
Granted: 1908-02-08
Abstract: 634. British Thomson-Houston Co., and Wedmore, E. B. Jan. 9. Distributing; switches.-In alternating-current distribution systems by feeders to sub-stations, switches are provided in the feeders such that, upon failure of one feeder, current is derived from the other feeders to open all the switches, or to open a section switch in one bus-bar, which may then operate to open the feeder switches, either the section or feeder switches being self-restoring or re-set by an attendant ; the faulty feeder remains cut out. Feeders 5, Fig. 1, with switches 8 supply sub-station bus-bars 2<1>, 2, the former of which is earthed, while the latter has a sectionalizing-switch 4 acting oppositely to a switch 11 which connects coils 10, used to close the switch 4, to earth or to the earthed bus-bar 2<1>, the coils 10 being connected to opposite feeders through tripcoils 9. To prevent the faulty feeder from being energized by the sound one through coils 9, 10, switches 12 are opened when the switches 8 open ; or, double-pole sectionalizing and auxiliary switches are used. The self-restoring switch 4 has a tripcoil 6, energized by a no-voltage device but prefer ably by differential transformers 7 supplied' by, the feeders 5 so that on the occurence of a fault in one feeder, the switch 4, is opened and the switch 11 closed, and current flows from the sound feeder to trip the switch 9 of the faulty feeder; and to energize the coil 10, preferably after a time limit, to close the switch 4, leaving the bus-bar 2 fed by the sound feeder only, In high-tension systems, instead of energizing the trip coils 9 direct from the feeders, potential transformers may be used. In a simpler arrangement, the coils 9, 10 are not used, the coils 7 operating, the coil 6 to open the switch 4 and leave one section of the bus-bar, dead, the feeder switch being, opened and the switch 4 closed again by anattendant. In a modification, the switch- 4 is not used, but all the switches 8, which are self-restoring are opened by the coils 9 being connected direct to the transformer coils 7; the sound-feeder switch is closed again by a shortcircuit coil 18, Fig. 5; which has a switch 12 working oppositely to the switch 8, which, as shown, may, be replaced by two swishes 20, 20<1>, on duplicated portions 5<1> of the feeders, one switch being normally open when the other is closed, and the normally-open switch being, closed by the. release of a weight or the like when. the other switch opens. With a number of feeders in parallel, the transformers 7, Fig. 8, are placed in series, and the coils 9 in shunt, while in any cases the coils 18 may' be energized by transformers 21. These arrangements may be provided, in duplicate for a twophase system, and in duplicate or triplicate for a three-phase system. The self-restoring switch, operated by hand or automatically, is preferably of the type in which contacts are immersed in oil;in the form preferred, a spring A, Fig. 9, which is compressed when the switch is opened, and may surround the operating-rod d or be in a separate casing a, engages one arm of a bell-crank lever b mounted on the casing, the other arm being connected by a pin and slot to a link c on the rod d. The spring is compressed when the switch opens, by a motor or by the lever b, toggle-links e, e and f, f being straightened. In closing the switch by hand, the spring A is unaffected. To release the spring, the solenoid core h is projected against the toggle f, f. In a two-phase system, the selfclosing coils are preferably duplicated, and act on the end of a rocking beam the middle of which actuates the toggle. In a three-phase system, the three coils act at the corners of a triangular plate, the centre of which is flexibly connected, as by a ball-and-socket or universal joint, to the toggle. release.