GB597274A - Improvements in and relating to automatically controlled electric lighting systems - Google Patents

Abstract

597,274. Visible signalling apparatus. STERN, W. L. June 24, 1946, No. 16456/45. [Class 118 (ii)] [Also in Group XXXV] The automatically controlled lighting system of a flashing buoy or beacon comprises a lamp bulb 4 containing two or more similar filaments (three filaments 1-3 being used in the example), a flashing-switch 8 in the supply circuit to the filaments, and, magnetic relay switches 9, 11 which operate to insert another filament in the circuit when a filament fails, each filament, except the last, being in series with the operating coil of a relay, and each operating coil being associated with a holding coil which is connected across the flashing-switch. Filament 1 is in series with two relay coils 10, 13 which are connected in parallel and hold the contacts 9, 11 open when the filament is energized. When filament 1 fails the contacts 9 close and complete the circuit of filament 2 through coil 12 which serves to hold open the contacts 11 in the circuit of filament 3, and contacts 21 in the circuit of an alarm or signal lamp 23. Failure of filament 2 serves to close the circuits of filament 3 and alarm lamp 23. The flashing-switch 8, which operates in known manner, has a condenser 17 and variable resistance 19 in parallel with the operating coil 16 to provide adjustment of the flashing period. In a modification the successive control of the circuits of the several filaments is effected by a ratchet switch with an electromagnet acting in opposition to a spring which steps a ratchet wheel round when the circuit of a filament is broken. The filaments are sufficiently close to employ the same lens system ; alternatively, the position of a filament relative to the lenses may be altered by relayoperated means combined with the filament changing relays.