GB190809850A - Improvements in or relating to Electric Signalling Systems for Railways and the like. - Google Patents

Abstract

9850. Boult, A. J., [Union Switch and Signal Co.]. May 6. Automatic systems; electric railways and tramways, signalling on.-In an alternating - current signalling-system employing polyphase signalling- currents, and in which the track rails are electrically continuous without insulating-pieces, the windings of the relays are arranged in parallel with respect to the exciting-transformers, and in series with respect to any other currents impressed on the rails. Each signal 21, 22 may be controlled by two relays with local contacts in series, both relays being energized by one transformer situated between them. In Fig. 2, one manner of carrying out the invention is shown. The single-phase transformer 24 supplies current to the track rails 5<a>, 6<a> through a capacity 27 and an inductance 28, this being equivalent to a two-phase supply to the track rails, across which the coils 16<a>, 17<a> of the relays are connected, the transformer and the two relays being connected by a return lead. In modifications, two-phase current is supplied from a generator through transformers. A train on the section short-circuits one or other of the relays, thus opening the signal circuit. Leakage currents across the track rails pass through the two coils 16<a>, 17<a> of the relays in series, and do not energize them.