Patent GB-174365-A (GB)
Abstract: 174,365. Siemens & Halske Akt.-Ges. Jan. 21, 1921, [Convention date]. Automatic exchange systems. - Relates to systems in which a wanted line or trunk is selected over one route, the call being subsequently transferred to a separate speaking route comprising a number of switches in series. In order to prevent false connections being made when a number of speaking routes are set up simultaneously, the test circuits extend through the setting and speaking routes and include a transformer winding or other source of energy individual to the part of the test circuit in the setting routes. The invention is described as applied to two systems; in the first a calling line is extended to the called line over two-co-ordinate selectors and the speaking route is set up over hunting switches. In the second system, a group selector having an idle trunk in the required level is selected by path-finder switches which are released when the selector is operated. In the system shown in Fig. 1, a subscriber Tn1 at exchange A selects a wanted line Tn101 at exchange B over non-numerical switches AS2, VW2, selector IGWI, trunk line 201, selector IIGW201, and connector LW201, and if the line is idle non-numerical switches AS11, VW11, VW31 connect it to the trunk 201, the selector IIGW201 and connector LW201 being released. The terminal banks of the switches such as VW11, are divided into two parts, the first part having access to group-selectors IGW for outgoing calls and the second part having access to switches VW31 &c. for incoming calls. The test circuit of the switch VW11, for the latter type of call, includes the setting route, normal contact K31 of switch VW31, and back contact of relay HR 31. When a switch VW31, having access to the incoming trunk 201, is found, the relay HR31 establishes a new testing circuit for switch VW31 which includes the setting route and the front contact of relay HR31. This system is shown in detail in Figs. 2<A>, 2<B> and 2<C>. Connection of calling line Tn1 to group-selector IGW1, Fig. 2<A>. The line relay R energizes a common starting-relay An which controls the rotary magnets D1 of idle line-finders AS1. When the calling line is found, the test relay P disconnects the rotary magnet D1 and energizes a slow-acting relay V, which energizes the rotary magnet D2 of the switch VW1 and prepares the circuit of its test relay T1. When an idle groupselector is found, the relays T, P, T1, C energize in series, and the impulse relay A energizes over the calling line. The relays R1, RC only function when the finder AS1 is seeking a called line. Selection of wanted line over group-selector IGW1, repeater set Sst, finder-switch AS201, group-selector IIGW201, and connector LW201. The selector IGW1 extends the call in the usual way to a repeater Sst at the second exchange relays A1, V3, V4, V5 being energized. Relay V3 energizes the rotary magnet D4 of finder AS201, and when the calling line is reached, relays P2, T, energize, bringing relay R2 under control of relay A1 in the calling loop. The selector IIGW201, under control of relays A1, R2, extends the call in the usual way to an idle connector LW201, Fig. 2<c>, which under control of relays A1, R3 selects the wanted line Tn201. Establishment of speaking route. If the wanted line is free, the test relay P4 is energized, and the line relay R4 of the wanted line is excited over its upper winding, and contacts 90, 74, 58, 61, 59, 60. A line-finder AS11 finds the wanted line, in the same way as the finder AS1 found the calling line, relays P5, T3 being energized, the latter disconnecting the line relay R4 and connecting up a relay R5, which is energized over the same circuit as relay R4. (The relay R5 is not energized when connection is made to a calling line, as there is then no earth connection.) The relay P5 energizes a relay V10, which closes a circuit for the rotary magnet. D8 of the switch VW11. During the movement of its wipers over terminals leading to groupselectors, the circuit of the test relay T4 is opened at contact 103 by relay R5, and rotation continues until the terminals of a switch VW31, having access to the incoming trunk Sst, are reached, when a test circuit is completed over the b-lead of the setting route from leads b<11>, b101, relays RC1, RC2, contacts 111, 112, relay RC3, contacts 115, 114, 57, and the secondary 100 of a transformer Tr, which acts as a source of alternating current. The relays RC1, RC2, RC3 all energize. Relay RC1 completes the circuit of the test relay T4, which arrests the switch VW11, shortcircuits relay RC1, and locks up in series with relays T3, P5, C3. Relay C3 energizes the rotary magnet D9 of switch VW31, which rotates until its wipers reach the trunk Sst. The energization of relay C3 switches over the test circuit previously traced, so that, instead of including contacts 111, 112, and relay RC3, it passes over contact 126, wiper 127, contacts 132, 131 to transformer 100, relay HR having been energized by relay RC3. When the trunk Sst is reached, the relay RC2 is again energiz.ed, completing the circuit of the test relay T5 to arrest the switch VW31, and extend the trunk Sst to the wanted line. The relay T5 also energizes a relayV11, whereby the holding circuit of the relay T3, P5, T4, C3, is extended over the upper winding of relay T5, to relay C1, and brought under the control of relays V3, V5. The energization of relay C1 effects the release of the setting route. Ringing-current. Relay C1 also connects up the ringing relay L, which is disconnected by the back-bridge. relay Y when the subscriber replies. Release. The apparatus at exchange A is released when the calling subscriber hangs up; that at exchange B when both subscribers hang up. When the calling subscriber hangs up, relays A1, V3, V4 release, and during the interval between the release of relays V3, V4, the circuit of relay P is opened, thereby energizing the release magnet M of selector IGW1. When the called subscriber also hangs up, relay V5 opens the holding- circuit of relays C1, T5, C3, T4, P5, T3, thereby restoring switches VW31, VW11, AS11. Second system, Fig. 3. In this system, a calling line 214 is connected by its pre-selector IVW214 to an idle switch V and also through a line-finder AS to a group-selector D, which is set, in accordance with the first digit of the wanted number, on a particular row and hunts in this row for an idle switch P. The selected switches P, V then hunt simultaneously until thev both find a free line at the same time, the switch V a free group-selector G and the switch P a group-selector having a free outlet from that row of its contacts corresponding to the setting of the selector D, that is to the first digit of the wanted line. When a free group-selector having a free outgoing line in the required level is thus found, a test circuit is completed over the setting route from the transformer Tr, finder AS, line 301, switch V, line 302, off-normal contact 305 of selector G, contact 306 of a special control relay referred to later, line 307, switches P, D back to the transformer Tr. The switch G is then raised to the same level as the switch D was and rotates to find the free outgoing lead taken into use by the switch P. When this is found, the test circuit is again completed, this time over lines 309, 310, contact 311, lines 312, 313, 307 &c. as before. The switches D, P are then released and the connector LW set on the wanted line. The system is shown in detail in Figs. 4, and 4<A>. Connection of calling line to switch V and group-selector D, and selection of group-selector G. The calling line a, b, Fig. 4, is connected by a pre-selector VW in the usual way to a switch V, the relay R1 thus energizing the rotary magnet Dm2 of an idle line-finder AS. When this finds the calling trunk, the relays P, T1 energize, and the vertical magnet H of the associated groupselector D is energized by impulses repeated by relay R1 over contacts 23, 21, 19, 18. At the end of these impulses, the relay V2 closes the circuit of the rotary magnet Dm3, which rotates the wipers 31, 52 to find an idle switch P, whereupon the relay P1 energizes in series with a relay E1, Fig. 4<A>, which closes the circuit of the rotary magnet Dm5 of switch P. The relay PI also energizes a relay E, Fig. 4, which brings into circuit the rotary magnet Dm4 of switch V. The switches P, V rotate simultaneously until an idle selector G is found having an idle outgoing lead in the required direction, whereupon a test circuit is completed from the secondary of transformer Tr, contact 44, relays RC1, RC, normal contact 47 of selector G, contact 49 of a relay Si (referred to later), relay RC2, back to transformer Tr. Relays RC, RC1, RC2 energize. Relay RC1 energizes a relay HR, which arrests switch V. Relay RC2 arrests switch P, and closes a circuit for a relay E2 which prepares a circuit for relay V3. The relay RC energizes a relay V4. Operation of selector G and release of switches D, P. The lifting-magnet H1 is operated by a number of impulses equal to those operating switch D by a relay A, which is controlled over both the leads a2, b2 in parallel by the relay R1, Fig. 4. At the end of the impulses, the rotary magnet Dm6 is energized over contacts 72, 73, 75, 76, 77. When the line taken into use by the switch P is found, the circular test circuit is again closed, this time from transformer secondary 43, contact 44, relays RC1, RC, contacts 78, 79, wiper 80, wires 81, 50, relay RC2, to transformer 43. The relays RC, RC1, RC2 again energize. Relay RC arrests the selector G by disconnecting the rotary magnet Dm6 and emergizes a relay B over its third winding, thereby interrupting the test circuit at contact 79, and extends the calling line to the connector LW. On the first vertical movement of the selector G, the opening of contact 47 in the test circuit causes relay R02 to close the circuit of relay V3, and the subsequent re-en