GB190506958A - Improvements in and relating to Safety Devices for Overhead Wires for Electric Traction and other Purposes - Google Patents

Abstract

6958. Burnett, H. R. April 3. Conductors. - Relates to safety devices for the overhead conductors used for electric traction, lighting, and other purposes, and consists in attaching to the main switch or circuit-breaker an electromagnetic device which, in the event of the overhead conductor breaking, releases a spring or weight which opens the main switch. Fig. 1 shows the electro-magnetic device attached to the tripping-gear of a common form of circuitbreaker, and Figs. 2 and 3 applications of the combined device and circuitbreaker to overhead trolly wires. The electromagnetic device comprises a differentially-wound electro-magnet M', the armature A<1> of which normally keeps the links O<1>, P<1> in the position shown against the action of the spring S<1>. If either of the windings of the electro-magnet becomes de-energized, the armature is drawn upwards, thus releasing the spring, which then forces the links outwards and draws the stirrup L<1>, or a flexible cord, downwards. This causes the tripping-gear to release the circuit-breaker, which then cuts off the current. The tripping-gear can be operated independently of the electro-magnetic device. In the arrangement shown in Fig. 2, the trolly wires C are supplied with energy from the feeder through the circuit-breaker, the opposite ends being connected to earth through the differential coils of the electro-magnet M<1>. Should either of the trolly wires break, the corresponding winding will be de-energized and the circuit-breaker opened. In the modified arrangement shown in Fig. 3, two sections of trolly wire are connected to the same feeder through the switch, while the other ends of the conductors are connected to earth through electro-magnets M<3> which normally Keep theterminals T<3> in electric connexion. The differential coils are normally supplied with energy from the feeder, the circuit being completed through the pilot wires PT and terminals T<3> to earth. When a trolly wire breaks, the corresponding terminals T<3> are disconnected and the circuit-breaker caused to open as in the previous arrangement. The pilot wires PT may be arranged over the trolly wires so as to act as guard-wires against falling telephone &c. wires. Reference is made to Specifications No. 17,666, A.D. 1896, [Abridgment Class Locomotives &c.], No. 24,548, A.D. 1896, Nos. 4088, 4899, 16,814, and 17,383, A.D. 1901, and No. 2558, A.D. 1904.