Patent GB-191310685-A (GB)
Title: Improved Circuit Arrangements for Telephone Systems.
Filed: 1913-05-06
Granted: 1914-03-19
Abstract: 10,685. Siemens & Halske Akt.-Ges. May 6, 1912, [Convention date]. Exchange systems.-In order to lessen the time taken to find a calling line by the wipers, of a call-finder, or an idle out-going junction between operator's positions by a preliminary selector, the calling lines or outgoing junctions are arranged in comparatively small groups and each trunk, leading to a group selector or operator's position, terminates in several hunting-switches adapted to wipe independently over several different groups of leads. Fig. 1 shows a selector trunk IGW associated with three independently moving call-finders E<1>, E<2>, E<3>, each comprising four wipers wiping the contacts of a group of, say, 25 subscribers, one, N<27>, of whom is alone shown. The wipers a', a<2>, a<3>; b<1>, b<2>, b<3>; c', c<2>, c<3> are connected to common leads a, b, c, respectively, and the wiper d<3> is connected over its normal contact to the wiper d<2>, and this in turn over its normal contact to the wiper d'. The call-finders have separate actuating-magnets D', D<2>, D<3>, and a common test relav P. When a subscriber N<37> removes his receiver, his line relay R<37> closes a contact r<37> in the circuit of the group relay An<2>, which energizes the actuating-magnet D<2> over a circuit which at first includes the wipers d<3>, d<2>, d<1>, and contact an<2>, and afterwards the wipers d<3>, d<2> and the segmental contact engaged by the wiper d<2> in its off-normal position. When the wiper c<2> engages its contact z<37>, the relay P energizes in series with the cut-off relay T of the calling line; the relay P disconnects the interrupter U and extends the calling line to the group selector by closing contacts p<1>, p<2>. The relay T disconnects the line relay R<37>, and, by opening contact t<4>, throws its high-resistance winding T' into the test circuit so as to mark its line engaged both to other call-finders and to connectors such as LW. At the end of the connexion the contact m is opened, thus de-energizing the relay P, which again completes the circuit of the magnet D<2>, until the wiper d<2> reaches its normal position. In the system shown in Fig. 2 for selecting idle outgoing junctions, it is assumed that between two exchanges there are about one hundred junctions, to which all the A-operators have access, but in order to distribute the traffic equally among the junctions, they are divided into groups of about twenty lines each, so arranged that each group is the first to be taken in use by a certain number of operators. If all the lines of a group, which an operator should take into use first, are engaged, the operator can select a disengaged line from other groups. If an operator inserts a plug in the jack J, the actuating-magnet D<1> of the selector E' is energized at first over contacts 4, an<1>, d<1>, d<2>, d<3>, and after the first movement over contacts 4, d<2>, d<3>. When an idle junction is found, the common test relay P energizes in series with a relay T, individual to the junction. If all the junctions connected to the selector E<1> are in use, a relay An<1> is energized over the series-connected armatures of the relays T, so that the magnet D<2> of selector E<2> is energized over contacts 4, an<1>, an<2>, d<2>, d<3>.