Patent GB-191329615-A (GB)
Title: Improvements in or relating to Automatic or Semi-automatic Telephone Exchange Systems.
Inventor: BETULANDER GOTTHILP ANSGARIUS
Filed: 1913-12-23
Granted: 1914-12-23
Abstract: 29,615. Betulander, G. A. Dec. 24, 1912, [Convention date]. Automatic exchange systems.-The two-coordinate selectors which are generally employed for selecting a group of lines and making a connexion to an idle line of the selected group are replaced by two sets of single -coordinate switches, termed primary and secondary selectors. which make the desired connexion through a link or intermediate circuit, idle intermediate and outgoing lines being selected beforehand by a common selector which is temporarily taken into use. The arrangement indicated diagrammatically in Fig. 3 performs the functions usually fulfilled by a set of ten group selectors. The ten groups of outgoing lines 24, 25, 26 are wired to the terminals of ten secondary selectors 20, the lines of the first group 24 being wired to the first terminals of the different selectors, those of the second group 25 to the second terminals, and so on. A subscriber is connected to an outgoing line 24, &c. by a preliminary selector 13, a primary selector 17, and a secondary selector 20. To make the connexion, it is necessary to select a secondary selector 20 which is not only itself disengaged but in which also the outgoing line of the desired group is disengaged. A secondary selector which fulfils these two conditions is selected by a group switch 21, which is multipled to the first terminals of the primary selectors 17. The first operation of a primary selector 17, when it is seized by a preliminary selector 13, is to connect the calling line to the group switch 21, which receives the impulses representing the first digit. The switch 21 selects an available selector 20 and controls it to make connexion with the outgoing line belonging to the wanted group, and is then released. The primary selector 17 then moves forward again, leaving the switch 21 available for the control of other connexions, and connects itself to the link or intermediate circuit 19 terminating in the already. operated secondary selector 20. To enable several connecting-operations to be controlled simultaneously, there may be several group switches 21, say three, multipled to the first three levels of the primary selectors 17. Modifications of the general arrangement shown in Fig. 3 are described, the chief variations being (1) the use of the preliminary selectors 13 to fulfil the function of the primary selectors 17, (2) the arrangement of the selectors 17, 20 in call-finder fashion, instead of as forward-hunting switches, (3) the use of groups of relays to replace the selectors, and (4) an increase in the number of secondary selectors 20, so that the same outgoing line may be accessible through two or more of them. The circuit arrangements are shown in greater detail in Fig. 5, which illustrates how a line 47, 48 is connected to a line 83, 84 of a desired group. Primary selector 17 ; first operation ; selection of an idle group switch 21. The selecling operation at the substation consists, for each digit, in first grounding both the a and b lines, then interrupting the b line a certain number of times, and finally severing the ground connexions and connecting the two lines. It is assumed that the connexion desired is in the first group of outgoing lines, so that the digit transmitted is 1. The grounding of the line 47, when the impulse-sender at the substation is operated, energizes the magnets 33, 35 and the relay 51, which locks itself so as to be independent of the normal contact 50. The selector, which is of the construction described in Specification 6465/13, is started by the magnets 33, 35, the wipers 57, 58, 59 being raised off the terminals as long as the selector is in motion. Upon the opening of the normal contact 49, the magnets 33, 35 are left dependent on the circuit of the test wiper 55, so that, as soon as the ungrounded terminal of a disengaged group switch 21 is reached, these magnets are de-energized and the selector 17 comes to rest, the contact 60 marking the appropriated group-switch non-selectable to other selectors. Operation of the group switch 21 and of the secondary selector 20. The relays 63, 64 and the rotary magnet 37 of the group switch 21 are now energized over the wipers 58, 59. The magnet 37, under the influence of the current-interruption in the line 48, moves the wipers of the switch 21 a single step, corresponding to the digit transmitted. The switch 21 has eleven arms, which are kept out of contact with the springs 41 by a lifting-magnet 39, energized by the relay 63, but, after the switch 21 has been brought to the required position, the lines 47, 48 are disconnected from ground at the substation, and the relays 63, 64 and the magnet 37 are de-energized. The relay 64 is of the retardedrelease type, but the relay 63 at once de-energizes the magnet 39, which drops the arms of the switch 21 on to the first spring 41 in each row, thereby connecting these springs to segments 40 in the first ten rows and disconnecting the spring 41 in the eleventh row. The ten springs 41 in the first row are connected to the third wires 92 of the ten lines outgoing from the first of the secondary selectors 20, and the segment 40 is connected to a relay 42 individual to that selector. The second row similarly belongs to the second selector 20 and its lines, and so on. The lines of the outgoing group in which a connexion is desired are therefore represented individually by the first spring 41 in each of the first ten levels. If the first outgoing line in any of these selectors is already engaged, there is battery potential on the corresponding spring 41 (as explained below), and the relay 42 of that selector is energized and prevents it from being put into action. Upon the de-energisation of the magnet 39, a starting-circuit 74 is closed, which energizes the magnets 33, 35 of the first secondary selector 20, provided that that selector is not already engaged and that its first outgoing line is not engaged. (If the first selector 20 should be already engaged, so that the off-normal contact 82 is closed, or if its first outgoing line is engaged; in which case the relay 42 is energized as described above, the starting circuit 74 is extended over the contact 82 or 93 to the next selector.) The selector 20 moves from its normal position and by opening its normal contact 76 leaves the magnets 33, 35 dependent on the circuit of the test wiper 88, the terminals of which are multipled, along with those of the other selectors 20, to the springs 41 in the eleventh row of the switch 21. Since the first of these springs has been disconnected from the grounded segment 40, the solector 20 is brought to rest on the first outgoing line 83, 84. Battery is now connected, through the magnet 3 and wiper 87, to the spring 41 individual to this line, so as to mark it engaged in the group switches 21. Release of the group switch 21. This is effected by the energization of the release magnet 38 and lifting magnet 39 when the retarded relay 64 releases its armature. Primary seletor 17 ; second operation; selection of the link circuit 89, 90. When the line 47 is again grounded at the substation, the magnets 33, 35 of the selector 17 are again energized over the contact 97 (the normal contacts 49, 50 being now open so that the relay 51 is not energized) and the selector 17 is started in search of the link circuit 89, 90. As long as the wiper 55 is passing over the terminals allotted to the group switches 21, the magnets 33, 35 are kept energized by a circuit through the contacts 97, 98, but the contact 98 is arranged to open as soon as the group-switch terminals are passed, and the magnets 33, 35 are then left dependent on the circuit through the test wiper 55. When the terminals of the link circuit 89, 90 are reached, the selector 17 is brought to rest by the de-energization of the magnets 33, 35, because the wire 99 is disconnected from ground at the normal contact 100 of the selector 20. The c'eenergization of the magnets 35 connects the wire 99 to ground at the contact 60, so as to mark the link circuit 89, 90 non-selectable to other selectors 17. The connexion is now completed from the line 47, 48 to the line 83, 84 of the selected group. Release of the selectors 17, 20. This is effected by grounding the wire 101, so as to energize the magnets 34, which complete the circuits for the magnets 35, 33, the latter being in circuit with an interrupter 104 whereby the selectors are restored to normal as described in the above-mentioned Specification. Means are provided for marking the selector 20 busy until its restoration is completed.