Patent GB-195439-A (GB)
Abstract: 195,439. Baron, H., (Aldendorff, F.). Dec. 22, 1921. Automatic exchange systems; metering systems.-In a system in which the customary group selectors are replaced by ten-point numerical selectors leading to bank contacts of finderswitches in the different divisions of the exchange, the connection is first extended to an idle selector by a quick-acting line finder which controls a slow-acting finder associated with the engaged selector. When the slow-acting finder has established connection with the calling line the transitory path is released. In a 10,000-line exchange each group of 100 subscribers' lines is served by ten slow-acting call-finders CC, Fig. 1, associated with primary selectors GSI, the contacts of which are multipled in the banks of ten slow-acting finder switches TCI in the appropriate thousands division of the exchange, and the contacts of secondary selectors GSII associated with the switches TCI are multipled in the banks of ten slow-acting finder switches TCII associated with connectors WC serving the corresponding hundreds section in the exchange. Connection is first extended to the switches TCI, TCII, WC over transitory paths by quick-acting finders CF, DTI, DTII. A calling line S is extended by a quick-acting finder CF to an idle one of ten intermediate trunks pt previously selected by an associated switch PT and leading to a primary selector GSI, which in response to the thousands impulses selects a trunk it1 leading to the wanted thousands section of the exchange. In the meantime a slow-acting finder switch CC associated with the seized selector GSI fastens on the terminals of the calling line, the stopping circuit extending over wipers of switches Ic, PT, CC, CF. The inclusion of the identifying switch Ic in this circuit prevents the slow-acting finder CC from connecting with any calling line except the one on to which the quick-acting finder CF has been set. The switches CF, Ic are then rendered available for further use, whilst the switch PT sets itself upon another idle trunk. A pair of quick-acting trunk finders DTI in the selected thousands division now hunt for the seized trunk it1 and extend it to an idle second selector GSII (similar to the primary selectors GSI) preselected by an associated switch ST. The hundreds impulses operate the selector GSII to select a trunk to the wanted hundreds section, after which an associated slow-acting finder TCI fastens on the seized trunk it1 and the switches DTI, ST, ItI are released. In a similar manner connection is established to an idle connector WC in the wanted hundreds section first by a quick-acting finder DTII and switch TT, and afterwards by a slowacting finder TCII. The tens and units impulses set marking switches Td, Ud, Figs. 1 and 6, associated with the connector WC, a starting circuit for the connector being completed immediately the tens switch Td moves on to its first contact on the receipt of the first impulse. The marking switches Td, Ud, assist in ringing and in release. Metering is effected by a metering relay 133, Fig. 4, connected in series with the connecting relay 176 of the call finder CC. On the response of the called party an inductive winding 193<1> of the relay 176 is energized, this boost of current causing the response of the meter relay 133 which is marginally adjusted. In an overflow arrangement described with reference to Fig. 3, all the trunks from primary selectors GSI, G'SI, associated with a group of call finders serving 1000 subscribers are multipled in the banks of overflow quick and slow acting finders DTF, OTC. If all the ten finders TCI having access to the trunks from a selected contact of a primary selector GSI are busy, a quick-acting finder DTF extends conection to an idle overflow trunk preselected by a switch OTF and leading to an idle second selector GSII previously selected by an associated switch CTF having access to 50 or more second selectors GSII in the required thousands section of the exchange. During dialling the connection is transferred over a slow-acting finder OTC and the switches DTF, OTF are restored for further use. In the system described the trunks are four wire trunks, but this number may be reduced to three bv employing a common starting wire leading from the selectors to the quick-acting finders, a trunk seized by a selector being marked by the application of a potential to one of the voice current loads. Operation of quick-acting call finder CF, CF<1>, Fig. 4. Each group of 100 lines is served by two of these switches, each having two sets of wipers each serving 50 lines and advanced independently by separate driving magnets. The line relay 100 energizes a starting relay 107 (common to 50 lines) which closes circuits for the driving magnets 110, 112 of the wiper sets serving the group of 50 lines to which the calling line belongs. These wiper sets occupy different relative positions in the contact banks, and when once, say, the upper set of the switch CF, engages the calling line, the driving magnet 110 is disconnected and connection is extended to the impulse relay 147 of the switch PT by the test relay 128, which is energized in series with the cut-off relay 102. Relay 102 de-energizes the line relay 100 and removes a short-circuit from a metering relay 133, which, however, is marginally adjusted and remains inert. Response of the impulse relay 147 energizes a release relay 124 and closes a circuit for a relay 126, which locks up and energizes the driving magnet 160 of the switch Ic, which is arrested on contacts associated with the switch PT by the energization of a stopping relay 164 over the wiper 161 and conductor 155. Operation of primary selector GSI, Fig. 4. The impulse relay 147 of the switch PT energizes a release relay 185 and closes a circuit 149, 171, 174, 177 for the impulse relav 179 of the selector GSI associated with a trunk Pt preselected by the switch PT. The first series of impulses interrupts the circuit of the relay 147, which intermittingly de-energizes the impulse relay 179, thereby closing a circuit for the driving magnet 110<1>, which advances the wipers of the selector GSI to a trunk it1 leading to quick- and slowacting finders DT, DTI, TCI, Fig. 5, in the wanted thousands group. Operation of slow-acting call-finder CC, Fig. 4. The release relay 185 of the selector GSI also completes a circuit for the driving magnet 190 of the associated slow-acting finder CC. These switches and also the slow-acting finders TCI, TCII of the subsequent trunking stages are 100- point rotary switches of the no-normal type. When the calling line is reached the test relay 100<1> responds in a circuit including wipers of the switches Ic, CF, PT, breaking the circuit of the driving magnet 190 and preparing the circuit of the connecting relay 176, which is energized on the relapse of a relay 116<1> on the cession of the first series of impulses. Release of temporary circuits. Connecting relay 176 short-circuits the release relay 124 of the switch PT at contact 121<1>, the last-mentioned relay short-circuiting the connecting relay of the quick-acting finder CF. The relay 128 de-energizes relay 126 at contact 137 and completes a restoring circuit 150<1>, 110, 132, 122, 134 for the switch CF; the relapse of the relay 124 de-energizes the test relay of the switch Ic, which is made available for other calls, and energizes relay 170, which completes the circuit of the driving magnet 152<1> of the switch PT. As long as the test wiper 153' engages the test contact of busy trunks the relay 170 will remain energized, but when an idle trunk is reached it relapses and disconnects the driving magnet 152'. Arrangements may be provided bv which, if all the trunks are busy, the switch PT stops in a certain position until one becomes available. Extension of call to connector WC in the wanted hundreds group. Relapse of relay 116' on the cessation of the first series of impulses completes a circuit over wiper 114<1> of the selector GSI for a starting relay 201, Fig. 5, which closes circuits for the driving magnets 212, 210 of the quick-acting finders DT, DTI, which are arranged in a similar manner to the switches CF, CFI. One of these finders, say the switch DT, fastens on the seized trunk it1 and closes a circuit 223, 225, 228, 221, 229, 113<1> for a relay 163' of the first selector GSI, this relay locking. up and completing a circuit over contact 162<1> for an impulse relay 247 of the switch ST, Fig. 5, which in conjunction with an identifying switch ItI appropriates a trunk to an idle second selector GSII in a manner similar to that previously described with reference to the switches PT, Ic, GSI, Fig. 4. The selector GSII is now operated by the hundreds impulses to select a trunk it2 leading to quick- and slow-acting. finders DTII, DTIII, TCII, Fig. 6, in the wanted hundreds group, a quick-acting finder DTII then setting one of its wiper sets on the contacts of the seized trunk it2. During the transmission of the hundreds impulses the slow-acting finder TCI engages the selected trunk itl and the switches DT, ST, ItI are made available for further use. All these operations are performed in the same manner as analogous operations in the previous trunking stage. In a similar manner the switch TT, Fig. 6, in conjunction with an identifying switch ItII appropriates a connector WC, and an associated slow-acting finder TCII fastens on the selected trunk it2 and the switches DTII, TT, ItII are released. Operation of connector WC, Fig. 6. The tens impulses successively interrupt the circuits of the impulse relays 179, Fig. 4, 279, Fig. 5, and 347, 379, Fig. 6, thereby energizing the stepping magnet 403 of a tens designating switch Td in a circuit 387, 384, 400, 402 (the relays 385, 316<1> are energized on the response of the impulse relay 347). An arcuate wiper 406 of the switch Td is thereby advanced and applies potential