Patent GB-231549-A (GB)
Title: Improvements in or relating to telephone systems using automatic switches or their equivalent
IPC: H04Q3/00
Filed: 1923-11-06
Abstract: 231,549. Mercer, R., and Automatic Telephone Manufacturing Co., Ltd. Nov. 6, 1923. Automatic exchange systems.-Connections are established over two co-ordinate switches which are controlled by temporarily used " steering " apparatus, the usual individual controlling relays being dispensed with, and a feed-relay group including ringing and supervisory relays. All the switches are thus identical in construction, and have their wipers permanently connected to the incoming leads. The main steerer controls the switches by means of auxiliary two-co-ordinate switches to select the calling and called lines, with a subsidiary steerer if necessary, impulses being received from the calling subscriber's dial and from an automatic impulse sender which becomes associated with the calling line. The claims relate to the general lay-out of the steerers and switches, other features of the system being claimed in Specifications 231,796 and 231,797. The invention is described with reference to an exchange having 10,000 lines arranged in groups of 1000 lines, each with corresponding groups of main and subsidiary steerers and feed relay groups. A calling line is connected by relays R1, R2 (or alternatively, a line switch) to an idle main steerer selector MSS, with which is associated an impulse sender IS connected so as to transmit impulses corresponding to the last three digits of the number of the calling line. The switch MSS selects a main steerer MS, which is associated over a preselecting switch TF with a feed relay group TR terminating in selectors FS, GS. The relay group TR is connected to the calling line over the group selector FS and a connector CF1, to which impulses from the sender IS are repeated by the main steerer MS. The auxiliary switch SS1 operates in synchronism with the selector FS and hunts for an idle connector CF1 which is then controlled over the wipers of the switch SS1. The relay group TR is connected simultaneously to the called line over the first selector GS, a second selector CFS and a connector CF2, to which dialled impulses are repeated by the main steerer MS. The auxiliary switch SS2 operates in synchronism with the first selector GS and hunts for an idle second selector CFS which is controlled over the wipers of the switch SS2, while the auxiliary switch SS3 moves vertically in synchronism with the first selector GS and then hunts for an idle subsidiary steerer SS, with which is associated an auxiliary switch SS4. The switch SS4 operates in synchronism with the second selector CFS and hunts for an idle connector CF2, which is then controlled over the wipers of the switches SS3, SS4. The connection is held by the switches SS2, SS4 while testing takes place, and relays in the relay group TR operate to complete the connection therethrough or to send back a busy signal. In either case, the main and subsidiary steerers and associated switches are released, the switch TF operates to preselect an idle relav group in readiness for the next call, and the relays R1, R2 release to switch through the calling line. Connection to main steerer MS. Line relay 10 energizes over the calling loop and connects up relay R1 and cut-off relay 13, which is shortcircuited over test wire 16 if the first main steerer selector is busy. In this case, relay R2 also energizes, and removes the short-circuit, and connection is made to the second main steerer selector. If both are busy. line relav 10 fails to energize. Assuming, however, that the first main steerer selector MSS is idle, relay 13 energizes and releases line relay 10. Line relay 24 energizes, grounds test wire 16, thereby locking relay R1, and connects up the stepping magnet 38 and series relay 37 which energizes in the usual way when an idle main steerer MS is found. switching through the line and test wires, and energizing relay 53. Line relav 62 of the main steerer MS energizes and connects up release relay 63 which grounds the test circuit 16, Fig. 2, 12. Fig. 5. Dialling tone may be connected to line relay 62. Relay 77 energizes over wiper 75 and impulse wire 74, and partially operates a two-step relay 86. Control of switches FS, CF1. The impulse sender IS has four banks of 25 contacts with two pairs of diametrically opposite wipers so as to be equivalent to a. two-wiper 50-point switch. Contact, corresponding to the thousands and hundreds digits are marked by relay 53, while those corresponding to the tens and units digits are marked by relays 13, R1. Relay 53 connects interrupter 66 to relay 69 to rotate the switch IS through magnet 71. Relay 72 energizes over wiper 73 at the first step, and removes earth from impulse wire 74, and sluggish relay 77, Fig. 5, remains held at front contact 78. No impulses are sent out however, since contact 89 of two-step relay 86 is open. Relay 84 energizes over wiper 83 and the first marked contact, and open-circuits relay 69, so that relay 77 falls back, and connects interrupter 107 to stepping relay 106. which by its first energization and subsequent de-energization causes two-step relay 110 to operate fully over test wire 112, connecting up the rotary magnets 113, 115 of the switches SS1, FS, the latter over wiper 114, and impulses are repeated thereto by relay 106. Two-step relay 116 energizes in a similar way to relay 110 and connects battery to test relav 122, which remains short-circuited over test wiper 124 of the switch SS1 until an idle connector CF1 is found, and then energizes, disconnects relay 106 and magnets 113, 115 and grounds test wiper 124. Wipers 133, 134 of the switch SS1 are thus connected to the vertical and rotary magnets 135, 136 of the connector CF1. Relay 137 energizes over test wiper 124, locks and disconnects the release magnet 142 and test wiper 131 of the connector CF1. By means of marked contacts in the bank of wiper 102 of the switch IS, tens and units impulses are now sent to the magnets 135, 136 to control the connector CF1, change-over being effected by two-step relay 145. Relay 72 is released at contact 252, but relay 84 holds over contact 251 to prevent further operation. If the calling subscriber hangs up before the calling line connection has been set up, the remaining intermediate contacts in the banks of wipers 73, 102 are earthed at contact 101, and the switch IS restores to normal. Control of switches GS. CFS. CF2. The thousands impulses are repeated at back contact 151 of line relav 62 to the vertical magnets 148, 149, 150 of the switches SS3, SS2, GS, sluggish relay 147 being held until the end of the train and then relapsing to allow two-step relay 154 to operate fully. Interrupter 107 is connected to stepping relay 156, and two-step relay 159 energizes fully at the first de-energization thereof over test wire 112 and connects up the rotary magnets 163, 165. 167 of the switches SS3. SS2, GS. Two-step relay 168 energizes fully at the next de-energization and connects battery to test relays 171. 176, which remain short-circuited over test wipers 173, 178 of the switches SS3, SS2 until in the former case an idle subsidiary steerer SS is found and in the latter case an idle second selector CFS is found, and then energize. Relay 176 disconnects magnets 165, 167 and relay 171 disconnects magnet 163. interrupter 107 being disconnected from relay 156 at two points. The hundreds digit is repeated over wiper 184 of the switch SS2 to the vertical magnet 185 of the second selector CFS, and over wiper 186 of the switch SS3 to the vertical magnet 189 of the switch SS4. Sluggish relav 187 holds up during the train, and then relapses, allowing two-step relay 190 to energize fully and connect interrupter 194 to stepping relay 193. Two-step relay 195 energizes at the first de-energization and connects up the rotary magnet 199 of the switch SS4 in parallel with the rotarv magnet 202 of the switch CFS over wipers 200, 201, and impulses are repeated at contact 197. Test relay 206 is connected un by two-step relay 203 at the second de-energization, and energizes when an idle connector CF2 is found and disconnects interrupter 194 and magnets 199, 202. Two-step relay 181, Fig. 5, energizes fully when relay 147 relapses at the end of the hundreds impulses, and the tens and units imnulses are repeated over wipers 186, 212, 214 to the vertical and rotary magnets 213, 215 of the connector CF2, change-over being effected by two-step relay 210. Two-step relays 216, 217 are energized at the end of these trains, and the latter connects battery over wiper 220 to test relay E in the feed relay group TR. Relays 226, 232a of the switches CFS, CF2 energize, lock and disconnect the corresponding release magnets 230, 236<a> and test wipers 224, 225. Release of main and subsidiary steerers MS, SS. Relay 217, Fig. 5 disconnects release relay 63 which removes earth from test wire 112 and test wiper 40, so that relays 37, 250, R1 relapse. Relay 53 falls back, and magnet 71 operates over contacts 400, 101 and advances the switch IS one step to normal. Relays 168, 116 release and open-circuit test relays 176, 171, 122. Relays 137, 226, 232<a> fall back and connect the test wipers 131, 224, 225 of the switches CF1, CFS, CF2 to the corresponding wipers of the switches SS1, SS2, SS4 to guard these switches temporarily. Relay 258, Fig. 6, which was energized over test wiper 173 and test wire 112 falls back and connects up the release magnet 259 to restore the switch SS4. Relay 238, Fig. 5, falls back, connecting up magnet 265 cf the switch TF and releasing relay 217 which at contact 243 connects up the release magnets 245, 246, 247 to restore the switches SS1, SS3. SS2, and at contact 244 connects earth to relay 238, which energizes when the switch TF finds an idle relay group and disconnects magnet 265. Called line busy. Relay E energizes over the forward test circuit 223, 224, 225, locks, connects busy tone to the lower talking wire and connects up the wipers